# Anyone have the SkyRC NC2500 charger?



## hatman (Jul 20, 2013)

Anyone have hands on experience with the SkyRC NC2500 charger?

How does it compare with the Maha 9000?

Thanks.


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## lowks (Jul 23, 2013)

Just a bump as I am also interested to know ... just seems impossible to find it though.


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## tatasal (Jul 24, 2013)

Seems to me like a just more expensive (but colorful) version of the C9000...


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## ChibiM (Jul 24, 2013)

It looks much better, even with Bluetooth!


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## lowks (Aug 5, 2013)

I have been using it for about two weeks now ... and from what I can see it's very similar. The difference here is: 

1. You can control functionality of the charger from iphone
2. The LCD display goes off after a while of charging.
3. There is a fan
4. Some of the measurements are more indepth (battery resistance)
5. Using the iphone / Android app you can change charging parameters of one / all slots. 
6. Plastic stand at the back seems pretty flimsy compared to Maha's one
7. There is a usb slot that provides charging for usb charge based devices.


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## Knight_Light (Aug 5, 2013)

Where did you get it?


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## shelm (Aug 5, 2013)

ru.nkon.nl is a European source for this item.


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## Knight_Light (Aug 5, 2013)

Thank You..


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## lowks (Aug 5, 2013)

Got mine at www.rc711.com. These guys are just cool! Very fast and flexible.


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## lowks (Aug 5, 2013)

One more thing I want to add is that the NC2500 also allows most of it's guard parameters like delta V and temperatures to be customized via the IPhone/Android app.


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## nkar (Aug 16, 2013)

Two questions :

1) Is the fan always on or kicks in incase of overheating ? How often kicks in?
Does it makes much noise? (i.e. can you sleep at the same room with the charger?

2) Have you tried charging C or D batteries? Can it charge it or there is a maximum mAh (like maha 9000)

Thank you


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## InHisName (Aug 17, 2013)

nkar said:


> 2) Have you tried charging C or D batteries? Can it charge it or there is a maximum mAh (like maha 9000)


Having read the manual last week, I remember that it has limit of either 3500 or 4500 MAH. I checked farther and it is the only factor NOT programmable !


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## lowks (Sep 7, 2013)

nkar said:


> Two questions :
> 
> 1) Is the fan always on or kicks in incase of overheating ? How often kicks in?
> Does it makes much noise? (i.e. can you sleep at the same room with the charger?



It's like the fan on those old CPUs kicking in when you are doing some heavy processing.


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## Floating Spots (Sep 12, 2013)

My old LaCrosse charger quit terminating on one channel. This was only a *few* dollars more than the Maha, so I ordered one. Looking forward to its arrival. 

Sent from my Nexus 7 using Tapatalk 4


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## Planz (Sep 12, 2013)

lowks said:


> Got mine at www.rc711.com. These guys are just cool! Very fast and flexible.



Is this made in Taiwan?
Looks like OEM from Maha?


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## lowks (Sep 12, 2013)

Planz said:


> Is this made in Taiwan?
> Looks like OEM from Maha?



Don't know if it's oem. On build and functionality it's like a better maha


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## Planz (Sep 12, 2013)

nkar said:


> Two questions :
> 
> 1) Is the fan always on or kicks in incase of overheating ? How often kicks in?
> Does it makes much noise? (i.e. can you sleep at the same room with the charger?
> ...





lowks said:


> It's like the fan on those old CPUs kicking in when you are doing some heavy processing.



I read the manual and it says there is a Turbo fast charging - 60 minutes to charge up 2500mAh battery. Is it the case that the fan only turns on when in Turbo charging mode or it can sometimes turn on even if it is not in Turbo charging mode?
Yes, if the fan does not kick in when not in Turbo mode, then that would be great.
I don't seem to be able to find in the manual how to set it to Turbo mode. Is it user selectable? I hope so as I don't normally use Turbo charging.
Thanks.


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## lowks (Sep 12, 2013)

The fan is purported to be "intelligent" and seems to just come on randomly. I don't know what algo it employs. Probably internal temperature. Afaik it's not configurable.


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## Planz (Sep 13, 2013)

lowks said:


> The fan is purported to be "intelligent" and seems to just come on randomly. I don't know what algo it employs. Probably internal temperature. Afaik it's not configurable.



Thanks lowks.

For those who might be interested, I compared the specs of the Maha and NC2500 using the manuals.
Here are the differences:


SpecsMahaNC2500Charging current.2 to2A0.2-2.5ADelta Peak?3-15mVDischarge termination1V0.5-1VMaintenance charge10mA30mATemp. protection?55-70CInput power12V 2A12V 2.5AUSB powernone5V 1ASupported capacity100mAh-2000mAh500mAh-3500mAhBattery tempNAyesBattery int. resistanceNAyesBattery volt graphNAyesBacklightAlways onOff after 10 minsFirmware upgrade?via smart phoneSmart fanNAyesBluetoothNAyescountry originTaiwan?warranty3 years1 yeardefault charge AA1000mA1000mAdefault charge AAA1000mA400mAButtons47


One "major" difference I noted was the maintenance charge.
10mA for Maha and 30mA for NC2500.

Can someone comment why NC choose a higher maintenance charge?
Is a lower maintenance charge better? (can leave it in the charger for longer duration)
Could it be that NC is capable of charging higher capacity cells and therefore has to up the corresponding maintenance charge?


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## Viking (Sep 13, 2013)

The Maha C9000 charging limit is 4000 mAh , not 2000 mAh.

The discharge termination is 0.9 V , not 1.0V. 
You can't upgrade the firmware on the Maha C9000.


Also the Maha C9000 has four separate temperature sensors. One for each slot.
The NC2500 manual says: "The charger has a built in temperature sensor". 
I guess that means all slots are sharing the same sensor.


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## Planz (Sep 13, 2013)

Viking said:


> The Maha C9000 charging limit is 4000 mAh , not only 2000 mAh.



My typo. The manual says 20,000 mAh not 2,000mAh. I will update.


SpecsMahaNC2500Charging current.2 to2A0.2-2.5ADelta Peak?3-15mVDischarge termination1V0.5-1VMaintenance charge10mA30mATemp. protection?55-70CInput power12V 2A12V 2.5AUSB powernone5V 1ASupported capacity100mAh-20000mAh500mAh-3500mAhBattery tempNAyesBattery int. resistanceNAyesBattery volt graphNAyesBacklightAlways onOff after 10 minsFirmware upgrade?via smart phoneSmart fanNAyesBluetoothNAyescountry originTaiwan?warranty3 years1 yeardefault charge AA1000mA1000mAdefault charge AAA1000mA400mAButtons47


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## Viking (Sep 13, 2013)

Planz said:


> My typo. The manual says 20,000 mAh not 2,000mAh. I will update.




Thats only in break-in mode. The regular charging limit is only 4000 mAh.
Also The discharge termination is 0.9 V


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## Planz (Sep 13, 2013)

Viking said:


> Thats only in break-in mode. The regular charging limit is only 4000 mAh.
> Also The discharge termination is 0.9 V



Thanks for the clarification.
I got the data from the manual "PRINTED IN TAIWAN A03-3713420-496" and copyrighted 1998-2007 so I am not sure if this version is the latest.


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## Viking (Sep 13, 2013)

Unfortunately , I don't think the manual mentions anything about the reguler charging limit.


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## Power Me Up (Sep 13, 2013)

Planz said:


> Thanks for the clarification.
> I got the data from the manual "PRINTED IN TAIWAN A03-3713420-496" and copyrighted 1998-2007 so I am not sure if this version is the latest.



As far as I know, the manual hasn't been updated since the original version which did indeed have a 20,000 mAh limit for all modes and terminated discharges at 1.0V (no load) 

Since the original version hasn't been available for a long time now, I think it would make sense to update your table with the details for the current version, even though it conflicts with what the manual says.


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## Planz (Sep 13, 2013)

Yes, I'll be happy to update the table if someone could tell me what the values are for the current version.
Please be specific if the parameter is different from the spec I have listed.
Thanks. Interim update:


SpecsMahaNC2500Charging current0.2 to2A0.2-2.5ADelta Peak?3-15mVDischarge termination0.9V0.5-1VMaintenance charge10mA30mATemp. protection?55-70CInput power12V 2A12V 2.5AUSB powerNA5V 1ASupported capacity100mAh-20000mAh500mAh-3500mAhBattery tempNAyesBattery int. resistanceNAyesBattery volt graphNAyesBacklightAlways onOff after 10 minsFirmware upgradeNAvia smart phoneSmart fanNAyesBluetoothNAyescountry originTaiwan?warranty3 years1 yeardefault charge AA1000mA1000mAdefault charge AAA1000mA400mAButtons47


Maha manual: mahapowerex.eu/user-manuals/mh-c9000-manual-en.pdf 

(Note that the Maha manual has not been updated for quite some time)


NC2500 manual: http://www.skyrc.com/index.php?route=product/product&product_id=179


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## espresso (Sep 16, 2013)

On paper this looks like a step forward from C9000. It would be good to see some in-depth review and discuss the algorithms for charging. For example, the value of charge/discharge impulses. If they're 2,5A it's even worse for older cells than C9000.


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## gopajti (Sep 16, 2013)

said an NC2500 dealer

"The charger is not perfect, loudly, difficult to remove the middle batteries, seems not to work with some android version.."


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## markr6 (Sep 16, 2013)

Looks AMAZING! Works with an app, very cool!! A little costly but could be my next charger.

Made in China, btw


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## lowks (Sep 16, 2013)

markr6 said:


> Looks AMAZING! Works with an app, very cool!! A little costly but could be my next charger.
> 
> Made in China, btw




Aren't all of them nowadays ?


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## markr6 (Sep 16, 2013)

lowks said:


> Aren't all of them nowadays ?



It seems that way. I personally don't care but wanted to fill in the "?" in the table posted by Planz


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## Planz (Sep 16, 2013)

markr6 said:


> It seems that way. I personally don't care but wanted to fill in the "?" in the table posted by Planz



Updates below to include country of origin and charging limit:




Specs
Maha​NC2500​Charging current
0.2 to2A​0.2-2.5A​Delta Peak
?​3-15mV​Discharge termination
0.9V​0.5-1V​*Maintenance charge*
*10mA*​*30mA*​Temp. protection
?​55-70C​Input power
12V 2A​12V 2.5A​USB power
NA​5V 1A​Supported capacity
100mAh-20000mAh​500mAh-3500mAh​Charging limit
4000mAh​?​Battery temp
NA​yes​Battery int. resistance
NA​yes​Battery volt graph
NA​yes​Backlight
Always on​Off after 10 mins​Firmware upgrade
NA​via smart phone​Smart fan
NA​yes​Bluetooth
NA​yes​country origin
Taiwan​China​warranty
3 years​1 year​default charge AA
1000mA​1000mA​default charge AAA
1000mA​400mA​Buttons
4​7​


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## Viking (Sep 16, 2013)

The maha C9000 has temperature protection as well.
quote from there homepage. And remember this charger has 4 sensors , 1 for each slot:




> the temperature sensors will safeguard battery overheating
> 
> http://www.mahaenergy.com/faq-c9000/



Also the way it detects end-of-charge:



> The MH-C9000 uses a combination of Negative Delta V, Zero Delta V, Peak Voltage, time and temperature to determine the end-of-charge. In addition, proprietary algorithms are used.
> 
> http://www.mahaenergy.com/faq-c9000/


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## Planz (Sep 16, 2013)

Viking said:


> The maha C9000 has temperature protection as well.
> quote from there homepage. And remember this charger has 4 sensors , 1 for each slot:
> 
> 
> ...



Quick clarification on the comparison table:

NA means not available
? means value unknown yet. It does not mean not available.


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## Viking (Sep 16, 2013)

Oh .... I see


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## fabryd (Sep 18, 2013)

I wanna buy this charger, do you know if in the future the 3500mah limit will be in higher mahmps with fw upgrades?
That limit is only for break in batteries? For ex if i put a 4000mah battery in charge, not breakin, it will be fully charged?
Im so indecise between the nc2500 and the maha c9000


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## ChibiM (Sep 18, 2013)

What`s the best price at the moment for this charger? 

I really think its very good looking and has lotsof interesting features. 
I don`t think there will be AA NiMh batteries with 4000mAh any time soon!!! so don`tworry.


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## shelm (Sep 19, 2013)

i don't understand everything but in the review looks very beautiful:

http://reviewsdelinternas.blogspot.com/2013/09/skyrc-nc2500.html


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## Power Me Up (Sep 19, 2013)

shelm said:


> i don't understand everything but in the review looks very beautiful:
> 
> http://reviewsdelinternas.blogspot.com/2013/09/skyrc-nc2500.html



You can use Google Translate to get something a bit easier to understand:
http://translate.google.com.au/tran...u/2013/09/skyrc-nc2500.html&biw=1920&bih=1032


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## lowks (Sep 19, 2013)

Personally for me the fan's temperature detection is spot on. I have tried putting in a few warm batteries and it starts up straight away. Once the batteries cool down after a bit, it then switches off.


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## fabryd (Sep 20, 2013)

ChibiM said:


> I don`t think there will be AA NiMh batteries with 4000mAh any time soon!!! so don`tworry.



i've found on ebay 4800mah AA batteries, but i dont know if they are fake
(btw i just orderd the NC2500 )


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## TinderBox (UK) (Sep 20, 2013)

Channel 2 on my C9000 will not charge any more, but will discharge fine, so i will be looking at the NC2500 as a replacement.

John.


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## stp (Sep 20, 2013)

fabryd said:


> i've found on ebay 4800mah AA batteries, but i dont know if they are fake
> (btw i just orderd the NC2500 )



Fake, it's impossible with current technology.


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## fabryd (Sep 20, 2013)

stp said:


> Fake, it's impossible with current technology.



Yeah thats what i thought, i could link the ebay auctions but dont know if its forbidden in this forum.

Btw i actually use 3000 mah star batteries in my camera and rc transmitters and they last long time, and 3000 is so close to the 3500 limit of the charger


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## jtr1962 (Sep 20, 2013)

fabryd said:


> i've found on ebay 4800mah AA batteries, but i dont know if they are fake
> (btw i just orderd the NC2500 )


2800 mAH is about the highest capacity possible with current technology. Even at that, reliability greatly suffers when you try to get capacity up that high. IMO, you really can't make a reliable AA with more than ~2500 mAh.


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## Norm (Sep 20, 2013)

OK, you guys have piqued my curiosity, just ordered one on ebay :naughty:, also order a replacement power supply as the one supplied is EU.

Norm


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## shelm (Sep 22, 2013)

*NC2500 Battery Bays: How To Insert And Remove Batteries Safely*

*Inserting *batteries in the bays, instructions valid for both *AAA *and *AA *sizes:

you'll need both hands! 
slowly slide the battery tail(-) first into the bay, lightly touching the NC2500 (-)metal spring contact. 
consciously push the battery against this (-)metal spring contact, thereby depressing the spring. since the spring is quite stiff, this requires some force. 
*hold* the force of the spring tension and slowly tilt the battery such that the battery head(+) gets inserted. this way the battery pivots around the (-)contact, with no sliding or scratching action at this (-)point. 
the battery is in place. you can now let go off the force in the spring. 
*
Removing *batteries from the bays, instructions valid for both *AAA *and *AA *sizes:

you'll need both hands! 
the battery is in place. push the battery in direction of the battery tail(-), thereby compressing the (-)metal spring contact. since the spring is very stiff, this requires some force. 
*hold *the force of the spring tension and slowly tilt the battery such that the battery head(+) only gets removed. this way the battery pivots around the (-)contact, with no sliding or scratching action at this (-)point. 
you can now let go off the force in the spring 
in longitudinal direction, slide the battery tail(-) out of its holding place. the battery is fully removed. in other words, surely by pushing on the negative spring, you would simply raise the (+)positive end of the cell and lift out the (+)end first. 
*
Note: *
The above procedure is safe for your fingers  and the battery wrappers. I would even recommend this procedure for the Maha MH-C9000 for both *AAA *and *AA *sizes. The C9000 original instructions suggest that *AA *size batteries be _inserted _head(+) first. Problem with this is that sooner or later the Eneloop AA wrapper gets scratched/damaged/torn by the (-)metal spring contact when _removing _the cell tail(-) first.

Give me 5 kudos if you found this post helpful!!!!!


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## _UPz (Sep 22, 2013)

shelm said:


> i don't understand everything but in the review looks very beautiful:
> 
> http://reviewsdelinternas.blogspot.com/2013/09/skyrc-nc2500.html



Thanks for the link! :thumbsup:


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## AleXis6 (Sep 22, 2013)

nkar said:


> 1) Is the fan always on or kicks in incase of overheating ? How often kicks in?
> Does it makes much noise? (i.e. can you sleep at the same room with the charger?




yes the fan is very noisy. I opened a ticket on SKYRC website about noise 1 week ago and I will put their answer here.


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## AleXis6 (Sep 22, 2013)

Viking said:


> The NC2500 manual says: "The charger has a built in temperature sensor".
> I guess that means all slots are sharing the same sensor.



Skyrc nc2500 has 4 Temperature sensors
I have this device and I see in my iPhone 4 different temperatures


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## Viking (Sep 23, 2013)

AleXis6 said:


> Skyrc nc2500 has 4 Temperature sensors
> I have this device and I see in my iPhone 4 different temperatures



Thanks that is above average for both chargers then , and I think should be included in the specs.
For instance , both the BC-700 and the BC-900 has only two sensors.


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## Planz (Sep 24, 2013)

Updates to include number of temp. sensors.


SpecsMahaNC2500 Charging current0.2 to 2A0.2-2.5A Delta Peak?3-15mV Discharge termination0.9V0.5-1V Maintenance charge10mA30mA Temp. protection level?55-70C # of temp. sensors44 Input power12V 2A12V 2.5A USB powerNA5V 1A Supported capacity100mAh-20000mAh500mAh-3500mAh Charging limit4000mAh? Battery tempNAyes Battery int. resistanceNAyes Battery volt graphNAyes BacklightAlways onOff after 10 mins Firmware upgradeNAvia smart phone Smart fanNAyes BluetoothNAyes country of originTaiwanChina warranty3 years1 year default charge AA1000mA1000mA default charge AAA1000mA400mA Buttons47 Notes: For granularity on the above table, refer to this thread's discussion and the manuals below:Maha manual: mahapowerex.eu/user-manuals/mh-c9000-manual-en.pdf http://www.mahaenergy.com/faq-c9000/NC2500 manual: http://www.skyrc.com/index.php?route...product_id=179


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## AleXis6 (Sep 26, 2013)

Hi everyone.
There are oscilograms about work of SKYRC NC2500 with Eneloop AA.
Charge current 1A (Duty approx. 35%, when charge current =0,2A ->Duty is 7%, 2,5A ->Duty is 86%) 




5 minutes after finished fast charge step (you can't see this activity in iPhone/Android) -you just see DONE, but battery is charging with a little current exactly 2 hours, and after that with very very little current (sorry I don't know how long)




Dicharge current 0,6A




So very interesting 
V max = up to approx. 2.5 volt ( I've never seen such hi voltage in BC and MAHA)


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## AleXis6 (Sep 26, 2013)

Viking said:


> both the BC-700 and the BC-900 has only two sensors.



yes 
SKY more close to MAHA


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## AleXis6 (Sep 26, 2013)

*Planz
*Could you please add to the comparison table
that SKY has a very noisy Fan without possibility to control it .
I think it is one of the biggest disadvantage of this device.
I think I will change this fan or reduce the speed or ... use SKY in a fridge 
I didn't find any new firmware and even I didn't find any tabs in a software how can I upgrade the firmware


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## Planz (Sep 26, 2013)

Here you go -


SpecsMahaNC2500Charging current0.2 to 2A0.2-2.5ADelta Peak?3-15mVDischarge termination0.9V0.5-1VMaintenance charge10mA30mATemp. protection level?55-70C# of temp. sensors44Input power12V 2A12V 2.5AUSB powerNA5V 1ASupported capacity100mAh-20000mAh500mAh-3500mAhCharging limit4000mAh?Battery tempNAyesBattery int. resistanceNAyesBattery volt graphNAyesBacklightAlways onOff after 10 minsFirmware upgradeNAvia smart phoneSmart fanNAyesFan NoiseNoneVery NoisyBluetoothNAyescountry of originTaiwanChinawarranty3 years1 yeardefault charge AA1000mA1000mAdefault charge AAA1000mA400mAButtons47Notes: For granularity on the above table, refer to this thread's discussion and the manuals below:Maha manual: mahapowerex.eu/user-manuals/mh-c9000-manual-en.pdf http://www.mahaenergy.com/faq-c9000/NC2500 manual: http://www.skyrc.com/index.php?route...product_id=179


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## Planz (Sep 26, 2013)

AleXis6 said:


> Hi everyone.
> 
> 
> Dicharge current 0,6A
> ...



Can you help me understand what this 2.5V is referring to? Thanks.


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## shelm (Sep 26, 2013)

AleXis6 said:


> I think I will change this fan or reduce the speed or ... use SKY in a fridge
> I didn't find any new firmware and even I didn't find any tabs in a software how can I upgrade the firmware



Latest firmware is v0.9.7, see https://play.google.com/store/apps/details?id=com.revogi.smartcharge

Just install it and once you connect through bluetooth the app will ask you about the firmware upgrade.

The fan is temperature controlled, so a new firmware could address the heat generation in the cell imho, not the heat removal through the smart fan. Just an idea.


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## AleXis6 (Sep 26, 2013)

2,5 volt it is just voltage level of 5-th horisontal line at this graf


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## AleXis6 (Sep 26, 2013)

shelm said:


> Latest firmware is v0.9.7, see https://play.google.com/store/apps/details?id=com.revogi.smartcharge


I installed this version after I bought the charger more than week ago

I received the answer from SKY support:
_It will get some noise during charging process due to the RPM speed of the fan is very high. We have to make sure the heat-removal system is good enough.

Anyway,*you can open up the charger and unplug the fan if you can do it.* Thank you._

strange. it seems that this fan is not needed.
 or my charger will died soon from overheating
I opened the charger when fan started to run and found that some parts inside had t=56 degreeC
inside:



fan model is
5volt
YM0503PVS1 30x30mm




Sleeve bearing + 1 ball bearing
Rated Voltage: 5
Voltage range: 3.5-5.5
Current: .14A
Input Power: 0.7W
Speed: 10000RPM
Air flow: 3.4CFM
Noise: 33 db-A
Weight 5g


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## Planz (Sep 26, 2013)

AleXis6 said:


> I installed this version after I bought the charger more than week ago
> 
> I received the answer from SKY support:
> _It will get some noise during charging process due to the RPM speed of the fan is very high. We have to make sure the heat-removal system is good enough.
> ...



Does setting the protection temp. at 70C using smart phone make the fan come on at a higher temp?
If so, charging at 1C perhaps may not turn on the fan?


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## AleXis6 (Sep 27, 2013)

Planz said:


> Does setting the protection temp. at 70C using smart phone make the fan come on at a higher temp?
> If so, charging at 1C perhaps may not turn on the fan?



just tested your idea.
I don't think so.
I wrote 65 degree in the program
cooler started after 20 minutes of charging process and I opened the charger and mesuared T was 45 degree

I removed 30mm cooler and drilled 50mm hole and attched 50mm fan from old computer (12v ->5v Silent).
Now I can sleep during the charging process.


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## Planz (Sep 29, 2013)

AleXis6 said:


> just tested your idea.
> I don't think so.
> I wrote 65 degree in the program
> cooler started after 20 minutes of charging process and I opened the charger and mesuared T was 45 degree
> ...



Interesting. Any pictures to share?


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## Floating Spots (Sep 29, 2013)

Received mine. Thought the Bluetooth might be a gimmick, but it makes it easy to setup all of the channels at the same time. 

Overall, I like it. 
However, my channel 4 measures significantly low on discharge capacity. I am going to have to do a full comparison, by cycling all four batteries, recording, and rotating. 
Charge measurements are near identical on the batteries (which seams just to be time vs charge rate) and all batteries are terminating near each other. However, during the discharge cycle, ch4 measures about 8% lower than the others. 

Sent from my Nexus 7 using Tapatalk 4


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## AleXis6 (Sep 29, 2013)

I will take a picture witn mew fan late when found an external grill.

response from SKY about fan:
_The fan is working for the whole parts of the charger.
It will start when the temperature reaches to 38℃._


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## Planz (Sep 30, 2013)

AleXis6 said:


> I will take a picture witn mew fan late when found an external grill.
> 
> response from SKY about fan:
> _The fan is working for the whole parts of the charger.
> It will start when the temperature reaches to 38℃._



The responses from the manufacturer seems rather inadequate.
They said you can unplug the fan and that sounds rather iffy to me.
Why have a fan in the first place if you can simply unplug it?
I'm also wondering what the 38C is referring to, temp of battery or a particular component?
If the manufacturer is watching this thread, do speak up.


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## Floating Spots (Sep 30, 2013)

Based off my observations, it is when any of the 4 batteries hit this temp. Now it may be keeping the internals cool, as well. 

Sent from my Nexus 7 using Tapatalk 4


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## AleXis6 (Sep 30, 2013)

Planz said:


> I'm also wondering what the 38C is referring to, temp of battery or a particular component?
> p.



_38 degree -> whole parts of the charger_
I immediately opened the charger after fan started and mesured temperature inside (by IR noncontact termometer) was maximum 40-55 degree.
now in my flat slightly cold - 20 degree and fan sometime stops and starts.
I think for hot climate this fan will be run all time because no radiators at all inside and some of the components slightly hot.


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## mactavish (Oct 1, 2013)

Really hope HKJ gets his hands on one of these to review. While I'm satisfied with my MC-9000, this charger looks interesting. Wondering what if any DISadvantages this one may have in comparison to the 9000 MaHa?


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## samgab (Oct 2, 2013)

mactavish said:


> Really hope HKJ gets his hands on one of these to review. While I'm satisfied with my MC-9000, this charger looks interesting. Wondering what if any DISadvantages this one may have in comparison to the 9000 MaHa?



Ditto what you just said. I just discovered this charger, and the iPhone graphing function looks amazing, but I'm wondering about build quality compared to my C9000 (which is very good). Fan noise seems to be a gripe some have with this charger, but I have mine in a room where it won't annoy me. I'm strongly considering buying one of these, but I'm dying to see an HKJ review first... If one is in the pipeline I'll hold off for a bit.

FYI, I noticed that DX are selling this charger for a good price.


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## Norm (Oct 2, 2013)

Norm said:


> OK, you guys have piqued my curiosity, just ordered one on ebay :naughty:, also order a replacement power supply as the one supplied is EU.
> 
> Norm


Still waiting for this to turn up, 11 days so far, paid very close to the DX price.

Norm


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## samgab (Oct 2, 2013)

Further to that comparison chart, there is the number of charge/discharge cycles each can do in cycle mode.
The Maha can do up to 12 consecutive cycles, and the SkyRC can also do up to 12.
I'd say the designers of the NC2500 probably took a C9000 and discussed how they could improve it, and the NC2500 is what they came up with. The physical dimensions and shape look quite similar to the C9000.
I think the defaulting to 400mA for AAA's is a big improvement over the C9000 which doesn't sense whether the loaded cell is AAA or AA.
In day to day life, using AAA and AA eneloops, I often don't want to cycle or analyse - just charge; and in those cases, when it is AA I just put them into the C9000 and let it do its thing, but when it is AAA's, I have to select the charge rate. 400mA is a perfectly acceptable rate for AAA eneloops, which I'd be happy to just plug in and leave them at.


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## Planz (Oct 3, 2013)

samgab said:


> I think the defaulting to 400mA for AAA's is a big improvement over the C9000 which doesn't sense whether the loaded cell is AAA or AA.
> In day to day life, using AAA and AA eneloops, I often don't want to cycle or analyse - just charge; and in those cases, when it is AA I just put them into the C9000 and let it do its thing, but when it is AAA's, I have to select the charge rate. 400mA is a perfectly acceptable rate for AAA eneloops, which I'd be happy to just plug in and leave them at.



Indeed. Defaulting to 400mA for AAA is so convenient.


SpecsMahaNC2500 Charging current0.2 to 2A0.2-2.5A Delta Peak?3-15mV Discharge termination0.9V0.5-1V Maintenance charge10mA30mA Temp. protection level?55-70C # of temp. sensors44 Input power12V 2A12V 2.5A USB powerNA5V 1A Supported capacity100mAh-20000mAh500mAh-3500mAh Charging limit4000mAh? Battery tempNAyes Battery int. resistanceNAyes Battery volt graphNAyes BacklightAlways onOff after 10 mins Firmware upgradeNAvia smart phone Smart fanNAyes Fan NoiseNoneVery Noisy BluetoothNAyes country of originTaiwanChina warranty3 years1 year default charge AA1000mA1000mA default charge AAA1000mA400mA # charge/discharge cycles1212 Buttons47     Notes: For granularity on the above table, refer to this thread's discussion and the manuals below:Maha manual: mahapowerex.eu/user-manuals/mh-c9000-manual-en.pdf http://www.mahaenergy.com/faq-c9000/NC2500 manual: http://www.skyrc.com/index.php?route...product_id=179


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## AleXis6 (Oct 5, 2013)

I finished first break-in in SKY nc2500 and found a negative info.

there were Eneloop xx revision B new (I bought them from nkon.nl).
I discharged them to 0,9 v and started breakin for capacity 2500.
first chargind phase 250ma x16 hours finished good (batteries temperature were below 40 degree) and all slots finished simultaneusly with displayed capacity 3999.
Discharge phase: unfortunatly due to poor balance between slots (slots 1 always finished discharge erlier) the differense in discharge time between slots were up to 20 min (slots 2and3 close to each other, slots 1and4 were very different).
I don't know what is the discharge capacity because I was outside my home and unfortunately the software can't show it.!!!!!! it is very stupid i think.
final charging phase - the temperature of 2 batteries (slot 3,4) achived 43 degree and I saw negative delta V for them at iphone graph. and finaly I saw charging capacity again 3999.
It seems that break-in have to be improved -1. we have to see discharging capacity.
2. the current 1/10C in this charger for 16 hours - can overheat the battery - so it not safety for battery


----------



## samgab (Oct 5, 2013)

AleXis6 said:


> I finished first break-in in SKY nc2500 and found a negative info.
> 
> there were Ehenoop xx revision B new (I bought them from nkon.nl).
> I discharged them to 0,9 v and started breakin for capacity 2500.
> ...



1: Did you let the entire break-in cycle finish and then look at the LCD display? I don't know about the NC2500, but on the C9000 you get the discharged capacity readout AFTER the entire process (charge/discharge/charge) is completed. I would guess the same sort of thing would happen with the NC2500, since they seem to have pretty much copied, and improved on the C9000... But I could be wrong, as I haven't had any hands-on time with the NC2500 yet.Edit: I just confirmed from the NC2500 user manual, that it _does _operate as I mentioned above, the same as the C9000:
_"For REFRESH & ANALYZE, BREAK-IN, DISCHARGE mode, the total discharge capacity will be displayed" _(on the LCD screen for that slot at the completion of the program).​
2. A 16 hour 1/10C charge will _not _overheat cells. It is - by design - a very low charge rate, and it is no-where near enough to cause the electro-chemical reaction in NiMH chemistry to happen at a sufficient rate for them to overheat. Unless you are in an ambient temperature that is close to the cells' heat ceiling, like 60 degrees C ambient. Which I doubt, as you'd be dying of heat exhaustion. 
16 hours charging @ C/10 (aka 0.1 It ​A) (at ambient temp of 20 deg C +/-5 deg C) is the official International Electrotechnical Commission (IEC) charging procedure for test purposes as per IEC61951-2-2003 (7.1). It's a completely safe rate/time period, with NiMH chemistry.
Charging as specified above should be followed by discharging at 0.2C down to 1.0V (or 0.9V), and then followed by another timed charge for 16 hours at 0.1C. This is the process followed correctly by both the NC2500 and the C9000.

As for the differences between bays, I'd suggest that it could be due to the location of the fan right in the centre, it could be cooling the two centre cells more than the cells on the edges.


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## AleXis6 (Oct 5, 2013)

I have 5 different smart chargers, and MAHA 9000 I also have.
NC2500 has a lot of rooms for improvement.
please see the oscilograms I provided at previous page, the main differences with MAHA and another chargers - very strange charge current up to 3A in picks for all charge regimes for AA.
1A -Duty approx. 35%, when charge current =0,2A ->Duty is 7%, 2,5A ->Duty is 86%
but the picks of current always about 3A.


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## Planz (Oct 5, 2013)

Would these statements be correct and/or phrased correctly?

1. Maha C9000 has a pulsed constant 2A charge rate

2. NC2500 has a pulsed constant 3A charge rate


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## espresso (Oct 7, 2013)

3A pulses are pretty high. I wonder what happens when you have an older cell. High resistance and high current don't get along well. 
And I thought C9000 had high pulses. How bout discharging? If the discharge current is higher than that of C9000, this would render NC2500 even more useless for accurately testing older cells. Just observations...


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## Planz (Oct 7, 2013)

I have been googling whether higher current pulses are detrimental but found little info.
There's was a comment that the difference in temp with higher versus 'normal' current pulses is insignificant, though it does not quantify 'insignificant'.


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## gSPIN (Oct 13, 2013)

another review in russian this time if you can follow it.
lots of pretty pix & a few vids if you can't.
http://translate.googleusercontent....=18212&usg=ALkJrhhY_0RRjv6xdhd391AIzk9ZG9raXQ


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## Norm (Oct 16, 2013)

After waiting almost four weeks my charger has finally arrived, just playing with it now with some new Eneloops and some older Aldi LSD batteries (two of each).

Norm


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## samgab (Oct 16, 2013)

Norm said:


> After waiting almost four weeks my charger has finally arrived, just playing with it now with some new Eneloops and some older Aldi LSD batteries (two of each).
> 
> Norm



Cool: Do you have an iPhone to link to it?


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## Norm (Oct 16, 2013)

samgab said:


> Cool: Do you have an iPhone to link to it?


Yes, there's a lot more info available when using the app. 












Here's a graph of an Aldi AA LSD after ding a refresh = charge - rest 1 hour - discharge - charge.






Norm


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## Planz (Oct 17, 2013)

Norm said:


> After waiting almost four weeks my charger has finally arrived, just playing with it now with some new Eneloops and some older Aldi LSD batteries (two of each).
> 
> Norm



I ordered from rcmart on Sep 13 and it's still nowhere in sight even though rcmart claims they have shipped it on Sep 15th.
I was given a tracking number and when I checked with the Hong Kong post office, they said the tracking number is not in their system.
Anyway, paypal is now handling the case and rcmart has just given them another new tracking number.
Let's see whether I get my hands on one eventually.


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## shelm (Oct 17, 2013)

Norm said:


>



Nice charger!!

:huh:


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## Planz (Oct 23, 2013)

After waiting almost 6 weeks, I got the charger.
The first thing that surprised me was the high internal resistance of a relatively new battery.




[/URL][/IMG]


So I tried with another set of old batteries and the internal resistances seemed ok






I also measured the pulsed charging current: 3A


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## samgab (Oct 23, 2013)

Wow, the thermal images are fantastic thanks Planz... Can you possibly post some more, perhaps of them both side-by-side like you have them above, but filled up with 4 AA cells each, and at various charge/discharge rates and states of charge/discharge? That'd be cool. I wish I could afford a thermal imaging camera, or could talk work into buying one...


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## Norm (Oct 23, 2013)

Planz said:


> After waiting almost 6 weeks, I got the charger.
> The first thing that surprised me was the high internal resistance of a relatively new battery.
> So I tried with another set of old batteries and the internal resistances seemed ok


If you have a cell that seems to have high internal resistance, give the cell a few spins to make sure you have a good connection.

Norm


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## Planz (Oct 24, 2013)

Yes, I did notice when I first install the battery, it did not sit in fully and then I pushed the battery in a second time. Not sure if that is the problem but will spin it next time. I also messed things up and thought I'd share what I did.
I originally wanted to record the resistance of each battery and used that to track the value over time.
However, when I removed the batteries, I forgot to do that and they all got mixed up. So next time round, I'm going to write down the value on the batteries while the batteries are still in the charger.


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## Norm (Oct 24, 2013)

Planz said:


> I forgot to do that and they all got mixed up.


Must admit I've been guilty of doing a refresh on 4 cells then forgetting to note the results 

Norm


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## Planz (Oct 24, 2013)

samgab said:


> Wow, the thermal images are fantastic thanks Planz... Can you possibly post some more, perhaps of them both side-by-side like you have them above, but filled up with 4 AA cells each, and at various charge/discharge rates and states of charge/discharge? That'd be cool. I wish I could afford a thermal imaging camera, or could talk work into buying one...



Unfortunately, I ran out of batteries. I might be able to salvage 4 at most. 
Meantime, here's a couple which I took the first time round.
Observations:
1. Maha slot 2 seems to be hot even though there was no battery. 
2. The NC charger fan is generating just as much heat.




[/URL][/IMG]



[/URL][/IMG]


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## Planz (Oct 25, 2013)

I managed to find some batteries to do refresh and analyze.

Setup for NC Charger

4 AAA 750 mAh eneloops (less than 1 year old) taken from weighing machine. Found to be totally depleted to 0.2V.
Voltage recovered to 0.9V the next day except for 1 which reads 0.7V
All 4 batteries put into NC charger for refresh and analyze, 400mA charge and 200mA discharge.
Slot 4 contains the 0.7V battery.

Observations:
The readings for the int. resistance for the batteries read
Slot 1 265 mOhm
Slot 2 267 mOhm
Slot 3 269 mOhm
Slot 4 274 mOhm




[/URL][/IMG]

There was no change in int. resistance even after spinning the batteries in their holders.
I guessed I have 'ruined' the batteries by letting them over discharged.
As expected, slot 4 took longer to terminate as it has the highest resistance; about 10 minutes longer.
The batteries started discharging in about an hour, as per the manual.

Battery capacity at end of discharge:

Slot 1 684 mAh
Slot 2 734 mAh
Slot 3 712 mAh
Slot 4 697 mAh

Setup for C9000

4 AAA 750 mAh eneloops (less than 1 year old) taken from 2 remote controls
Voltage found to be about 1.28V each
All 4 batteries put into C9000 for refresh and analyze, 400mA charge and 200mA discharge.

Observations:

According to the C9000 manual, the battery should discharge after one hour of rest.
That did not happen. It took almost 2 hours before the batteries started to discharge.
In between the 2 hours, the voltage maintains at around 1.49V.

Battery capacity at end of discharge:

Slot 1 766 mAh
Slot 2 761 mAh
Slot 3 766 mAh
Slot 4 763 mAh 

Observations between C9000 and NC charger

When the C9000 did not discharge after more than 1 hour, I took a few thermal images.




[/URL][/IMG]

Even though the charger say it is resting, it does not look like it is. The charger seems to be still 'on'.
Compared with thermal image of the NC charger, when it rests, the temp drops fast and the charger seems to be 'off'. The voltage dropped to around 1.42V compared with C9000 which maintains at 1.49V

As a side note, the day before, I did a quick measurement on the NC charger discharge of an AA battery
At 1A discharge, the pulse current was 1.25A
At 0.5A discharge, the pulse current was 1.25A

So it seems like the discharge current is 1.25A pulsed as compared with C9000 which IIRC, is 2A pulsed.
The thermal image shows the batteries in C9000 are hotter than the batteries in NC charger in discharge mode.
In fact, the temp profile for C9000 is higher in discharge mode than it is in charge mode.
However, in charge mode, the thermal image shows the batteries in NC charger are hotter than the batteries in C9000.
The NC charges at a pulsed 3A and IIRC, C9000 charges at 2A pulsed?

Conclusion

Strictly speaking, this exercise is a partial characterization than drawing of conclusions. I do not have sufficient knowledge to draw meaningful conclusions. There are pros and cons of each charger but one major feature that I like so far is the ability of the NC charger to display the internal resistance. Under normal usage, I do not monitor the voltages of the eneloops. I normally only charge them after a device gives a low battery warning or until a device no longer works due to low battery voltage. This can be seen by the over discharged batteries in two of the devices that I use. If indeed the over discharged batteries resulted in high resistance, then the ability to conveniently measure/display the int. resistance is useful in reminding me to be more conscious of monitoring and not allowing the batteries to go into an over discharged state. There's probably quite a bit more to do and go back and check/verify the condition of the high resistance batteries but I'll leave it for another day when time permits.


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## samgab (Oct 25, 2013)

Planz said:


> ...the temp profile for C9000 is higher in discharge mode than it is in charge mode.
> However, in charge mode, the thermal image shows the batteries in NC charger are hotter than the batteries in C9000...



Thanks for the extra thermal photos, interesting stuff. It makes sense that the C9000 is hotter when it is discharging than when charging, because the energy of the cells discharging is being dissipated as heat inside the unit; whereas when charging, the cells themselves only start heating up when they approach 100% SOC, and the charger isn't producing as much heat when charging as it isn't having to dissipate all of the heat from the discharge process. I think the voltage regulator on the underside of the PCB puts out a fair bit of waste heat, which would occur when charging or discharging, but when discharging you have the additional heat of the power of the cells dissipating. So that would be highest if you were discharging 4 cells at the max rate 1A each. That's about 4-5.6 Watts of waste heat.



Planz said:


> ...Even though the {C9000} charger say it is resting, it does not look like it is. The charger seems to be still 'on'.
> Compared with thermal image of the NC charger, when it rests, the temp drops fast and the charger seems to be 'off'. The voltage dropped to around 1.42V compared with C9000 which maintains at 1.49V...



The C9000 follows the main charge with a 100 mA top off charge for 2 hours, then supplies a 10 mA trickle charge. The top off charge and trickle charge rates are not displayed, and the trickle charge continues until the cell is removed.

_Edit: sorry, the above is for when a charge completes, not for when it is "resting" in the middle of doing a refresh & analyze cycle... I've never checked what the C9000 does when doing a refresh/analyze because I very rarely use that particular function; however the manual I looked at does say the "rest" period (whatever they mean exactly by that) is 2 hours long:
_


> "First recharges the battery, rest for two hours, discharges, rest, then recharges again. Charging and discharging rates are programmable. "


I suppose it's possible that the C9000 follows its usual end of charge trickle charge process when "resting" after the initial charge in the middle of the refresh/analyze cycle?

FYI, the C9000 uses *2A *pulsed for *charging* at all selected charge rates, and *1A *pulsed for *discharging *at all selected discharge rates, just varying duty cycles of these rates. I had tested this previously, but I'd forgotten the figures, so I just retested on my C9000, using a Fluke 87V.


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## Planz (Oct 25, 2013)

samgab said:


> Thanks for the extra thermal photos, interesting stuff. It makes sense that the C9000 is hotter when it is discharging than when charging, because the energy of the cells discharging is being dissipated as heat inside the unit; whereas when charging, the cells themselves only start heating up when they approach 100% SOC, and the charger isn't producing as much heat when charging as it isn't having to dissipate all of the heat from the discharge process. I think the voltage regulator on the underside of the PCB puts out a fair bit of waste heat, which would occur when charging or discharging, but when discharging you have the additional heat of the power of the cells dissipating. So that would be highest if you were discharging 4 cells at the max rate 1A each. That's about 4-5.6 Watts of waste heat.



Makes sense. Strange thing though the NC chager seems to cool down in the discharge mode. When I put a piece of tissue paper under the fan slots, the paper got sucked toward the slots so I presume air gets in from below. The exit path cannot be felt with the hands nor a piece of paper. Doesn't seemed like the ventilation path is well designed. Could be due to design constraints. If you look at the thermal image of the bottom case above, the hottest region in around M1. Not sure if it's design constraints that don't allow them to put the fan there instead.


_



however the manual I looked at does say the "rest" period (whatever they mean exactly by that) is 2 hours long:

Click to expand...

_
You are right. I was reading from the manual revision A03-3713420-496 which says rest for one hour.



> FYI, the C9000 uses *2A *pulsed for *charging* at all selected charge rates, and *1A *pulsed for *discharging *at all selected discharge rates, just varying duty cycles of these rates. I had tested this previously, but I'd forgotten the figures, so I just retested on my C9000, using a Fluke 87V.



Thanks for the clarification on the discharge rate.


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## shelm (Oct 29, 2013)

the new firmware version was posted today.
you can download and install it.


> Updated
> October 28, 2013
> 
> Size
> ...


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## Norm (Oct 29, 2013)

shelm said:


> the new firmware version was posted today.
> you can download and install it.


From where?

Norm


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## shelm (Oct 29, 2013)

Norm said:


> From where?



From your iphone/android smartphone app search , search term < _skyrc _>

From PC, things are more complicated i guess.

check also:

https://play.google.com/store/apps/details?id=com.revogi.smartcharge


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## Norm (Oct 29, 2013)

OK an upgrade to the App or a firmware upgrade for the charger? My Iphone Apps upgrade automatically and that hasn't happened yet.

Edit : Looks like the Iphone App hasn't been upgraded since May 10 2013.

Norm


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## shelm (Oct 29, 2013)

the new app contains the new firmware. it is hidden inside the app. so there is no separate firmware download needed/possible.

as soon as the app is downloaded/updated/installed and you connect smartphone with the nc2500, the app informs on screen that the app can transfer an updated firmware to the nc2500 device.

i am on android with activated automatic app updating. the automatic app update worked fine on my android. then the new firmware is not automatically transferred, one has to confirm with YES / NO once the nc2500 is paired up.


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## Norm (Oct 29, 2013)

Thanks shelm, must just be android.

Norm


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## Floating Spots (Oct 29, 2013)

What are the current versions?
Mine did not go through the firmware update described. 
My revisions are App = 0.9.8, firmware 1.05.


Sent from my Nexus 7 using Tapatalk 4


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## shelm (Oct 29, 2013)

Floating Spots said:


> My revisions are App = 0.9.8, firmware 1.05.



0.9.8 contains 1.05
that was posted on October 28, 2013
that's the latest code!

0.9.7 contained 1.04, and was posted on September 1, 2013

apparently your devices (smartphone+charger) underwent some automatic updating without you noticing :nana:


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## AleXis6 (Oct 30, 2013)

> The first thing that surprised me was the high internal resistance of a relatively new battery.


it is inaccuracy of scyrc2500.
I have icharger and special tool for connecting battery and for example Rin 30mOM in I charger it is approximately 50-60 mOm in SkyRC2500


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## AleXis6 (Oct 30, 2013)

Planz said:


> I originally wanted to record the resistance of each battery and used that to track the value over time.



it is not needed due to not good connection battery/charger, so R of the connection comparable with Rin and every time you will see different mesuares


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## AleXis6 (Oct 30, 2013)

Norm said:


> Thanks shelm, must just be android.


I also see that android shows firmware version, but can't see this info in iphone


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## AleXis6 (Oct 30, 2013)

shelm said:


> 0.9.8 contains 1.05
> that was posted on October 28, 2013
> that's the latest code!


I updated it in Android
is it enough to update FW into the charger? or I have to press a special buttons?


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## AleXis6 (Oct 30, 2013)

samgab said:


> _ BREAK-IN, the total discharge capacity will be displayed" _(on the LCD screen for that slot at the completion of the program).​



see please http://s23.postimg.org/esqwvw1bf/Screenshot_2013_09.png
I disagree, at least at the previous FW it wasn't


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## samgab (Oct 30, 2013)

AleXis6 said:


> see please http://s23.postimg.org/esqwvw1bf/Screenshot_2013_09.png
> I disagree, at least at the previous FW it wasn't



Yeah all good. It was simply a quote from their user manual. I think they were referring to the display on the actual device LCD, but you'd know better than me. The amount of energy put into a cell on break-in (not brake-in, btw SkyRC, sheesh!) is of no use whatsoever as it's just timed charge rate x 16 hours. Hopefully this is something they remedy with updates.


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## AleXis6 (Oct 30, 2013)

samgab said:


> Hopefully this is something they remedy with updates.



I am checking new FW right now ...


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## Norm (Oct 30, 2013)

AleXis6 said:


> see please http://s23.postimg.org/esqwvw1bf/Screenshot_2013_09.png
> I disagree, at least at the previous FW it wasn't


One small difference I see in the Iphone version Break In is spelt correctly.

Just wondering why it only shows 3 cell locations in your picture? the Iphone version would show all 4 even if some were empty. From the screen shots I've seen I'd say the Iphone app is tidier than the adroid app, perhaps because of all the different screen resolutions for android.

Norm


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## Planz (Oct 30, 2013)

AleXis6 said:


> it is inaccuracy of scyrc2500.
> I have icharger and special tool for connecting battery and for example Rin 30mOM in I charger it is approximately 50-60 mOm in SkyRC2500



That's good to know. Even though I'm using it as a trend tracking aid, it seems the base accuracy is way off from the numbers you quoted.


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## Norm (Oct 30, 2013)

AleXis6 said:


> it is inaccuracy of scyrc2500.
> I have icharger and special tool for connecting battery and for example Rin 30mOM in I charger it is approximately 50-60 mOm in SkyRC2500


One Eneloop chosen at random showed 67mOHM on my scrc2500 the same cell tested on a SkyRC i-Meter showed 35mOHM 

At least this might be able to fixed with a firmware upgrade.

Norm


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## Planz (Oct 31, 2013)

AleXis6 said:


> it is not needed due to not good connection battery/charger, so R of the connection comparable with Rin and every time you will see different mesuares



Out of curiosity, I did some short experiments to get an idea of the repeatability readings from the NC charger.





[/URL][/IMG]

P.S. anyone can share with me how to format properly? I just did a copy and paste from excel.

I did another measurement of the same battery this time using a multimeter and a 1 Ohm load and got the following readings:
Voltage no load = 1.359V
Voltage with load = 1.25V (this reading fluctuates a fair bit so I try to take the first 'stable' reading)
Rint = (1.359-1.25)*1/1.25 = 87 mOhm

Above measurement and calculation method was from taken from HKJ's website 
http://lygte-info.dk/info/Internal impedance UK.html

Disclaimer: Any error is solely my own.


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## samgab (Oct 31, 2013)

Planz said:


> ...anyone can share with me how to format properly? I just did a copy and paste from excel.



You can use the "code" button that looks like a hash symbol #, but you would have to alter the original format a bit, as it only does one line per cell that way, so it ends up being a bit wide with the amount of text you have there.


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## Planz (Oct 31, 2013)

Thanks. I'll leave it at that for now and append image.
Also added measurement of internal resistance using multimeter and 1 Ohm external load.


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## AleXis6 (Oct 31, 2013)

Norm said:


> One Eneloop chosen at random showed 67mOHM on my scrc2500 the same cell tested on a SkyRC i-Meter showed 35mOHM
> 
> At least this might be able to fixed with a firmware upgrade.


I think no. It is hardware issue. The R of the connection is high. it must be very good Cu contacts for right Rin.
I tried to check Rin by icharger and standart wires and connection and it was 50mOm, after that I made special tool with short wires from high quality audio cabel

http://s17.postimg.org/hj5e7ongf/IMAG0240.jpg

after that the Rin 28-32mOm for new Eneloop AA


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## AleXis6 (Oct 31, 2013)

Norm said:


> Just wondering why it only shows 3 cell locations in your picture?



there are 4, but with strange shift data to left at the android  but correct for iPhone



Planz said:


> Rint = (1.359-1.25)*1/1.25 = 87 mOhm
> .


I am not so lucky with my SKY 2500.
Rin for same battery was from 55-to75 mOm


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## AleXis6 (Nov 1, 2013)

AleXis6 said:


> I am checking new FW right now ...



With new firmware situation as previous: after break-in I see just charging capacity=0,1C *16.
No any possibility to see discharge capacity if you weren't near the charger at that time.


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## samgab (Nov 1, 2013)

AleXis6 said:


> With new firmware situation as previous: after break-in I see just charging capacity=0,1C *16.
> No any possibility to see discharge capacity if you weren't near the charger at that time.



So the charger LCD _does _show the discharged capacity at "done"? If so, that is what I was trying to say anyway, I wasn't talking about what it says on the app. I even specified that that was what I was talking about in the original quote "..._(on the LCD screen for that slot at the completion of the program)._"
If you're within bluetooth range of the charger I'm sure it's not that much of a trial to walk to the charger and look at the LCD... Which you have to do to remove the cells from the charger anyway.


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## AleXis6 (Nov 1, 2013)

samgab said:


> So the charger LCD _does _show the discharged capacity at "done"?



No unfortunately.
just charging capacity 0,1C *16


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## samgab (Nov 1, 2013)

Wow. That's a bit of a design oversight. I get leery of a manufacturer that makes mistakes with the little details, like the spelling of "break-in" and the correct information to display upon completion of a cycle... It makes me wonder about how well they've paid attention to things in the more important unseen areas, like the PCB and circuit design, and what corners may have been cut. I have confidence in the Maha C9000. Not convinced about the NC2500. I'd love to see a teardown, pix etc.


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## Planz (Nov 1, 2013)

Planz said:


> Thanks. I'll leave it at that for now and append image.
> Also added measurement of internal resistance using multimeter and 1 Ohm external load.






I am not so lucky with my SKY 2500.
Rin for same battery was from 55-to75 mOm[/QUOTE]

I've edited my earlier post to indicate clearly the last measurement was made using a multimeter and not SKY 2500


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## lowks (Nov 2, 2013)

There is a new update to the iPhone app. Now we can set the trickle charge setting as well.


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## Power Me Up (Nov 9, 2013)

*Disclaimer:* Since I've written the firmware for another charger/analyzer, some may feel that I'm biased with the following. Feel free to take a truck load or 2 of salt with this:

I received one of these chargers only a day or so ago and so far I'm not very impressed!

Discharge accuracy seems to be very poor on the unit I've received. It appears that the charger doesn't measure the actual current when either charging or discharging. Running a refresh/analyze on a set of 4 Eneloops that I recently took out of the packet gave discharge capacities of:

1846
1831
1910
1711

Repeating the test with a different set of 4 Eneloops gave the following discharge capacities:

1850
1830
1912
1700

On the second test, slot 3 gave a capacity that was 12.5% higher than slot 4 - far more variation than I've ever seen between new Eneloops! There's an obvious pattern above - comparing slot to slot between the 2 tests gives variations ranging from 0.05% to 0.65% - what I'd expect with Eneloops.

The current shown on the display and in the Android app never varies from the set current. I also did a test charge on a known high resistance cell to see how it would handle it. The charger reported that it was charging at the set rate of 1 amp, but the voltage only went up extremely slowly (from about 1.28V to 1.30V over the whole time) so it appears that it simply wasn't actually charging the cell. I left it to see what would happen and it finally stopped charging at 5 hours and about 5Ah showing on the screen.

Given all of the above, I think it's reasonable to conclude that the charger doesn't measure actual current and is also not very accurate with its discharge currents and hence discharge capacity results.

The other major complaint that I've got is the fan noise. As reported by others here - it's really loud and doesn't seem to be achieving much - I can't feel any air coming out of the fan - it feels like it's trying to suck air into the charger, but I can't feel warm air coming out anywhere. Temperatures are fairly warm here, but not so high that I would expect that it should need to be running most of the time. Charging a set of 4 AAA Eneloops at 400mA, it had the fan running quite often - I think it's quite concerning that it can't handle 16% of its peak load without needing to have the fan running! What's more, I left 4 cells in the charger after the last refresh and analyze above and even after everything had stopped for quite a few hours, the fan was still coming on intermittently!

I've since set the temperature control to 70 degrees and it hasn't run the fan since which is good, but I haven't tried doing a charge yet.

The Android app is also quite buggy - besides a number of quirks, it has force closed on me numerous times. The Bluetooth range seems to be quite poor as well. If I walk out my office holding the phone, it loses the connection after moving only a few meters from the doorway - the Bluetooth connection actually has less range than the fan noise - that's how loud it is!!!

Being able to view the charge/discharge curves on the phone is certainly a nice feature. It would be even better if the data could be saved out to somewhere for more thorough analysis - this could of course be done with a future upgrade.

Overall, I think that the NC2500 is a good idea, but it's just poorly implemented. There are also a few other minor problems that I've noticed that I haven't mentioned above. 

At the moment, I'm considering selling this charger on Ebay and taking a loss. I'd be willing to overlook most of these problems, except for the inaccurate discharge results - in my opinion, a 12.5% variation is just unforgivable!

For anyone contemplating purchasing this charger, I'd recommend going for the Maha C9000 instead until something better becomes available. The C9000 isn't perfect, but it has far less problems than this charger...


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## Floating Spots (Nov 9, 2013)

I definitely agree that the charging cycle doesn't measure true current and is time versus setting. As long as that current is reasonably well calibrated, I am OK with it. 

Discharge seems to be measuring something. My channels 1-3 are fairly close to each other, while my channel 4 has ~5% error. However, they are finishing within minutes of each other. If this was simply timed, then the discharge current should be near identical. 

Now the error itself is a real problem. One of the channels should not be this far out from the rest. I have not opened this up yet. I want to, but it's kind of hard to convince myself that I really want to take apart my brand new, expensive charger. 

Sent from my Nexus 7 using Tapatalk 4


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## Norm (Nov 9, 2013)

I have gone as deeply into the charger as you have, I can only comment that the IR readings are twice what they should be, bluetooth is fine up to about seven metres (iphone), the fan on mine run for short periods and doesn't worry me.

Norm


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## austinios (Nov 10, 2013)

"the IR readings are twice what they should be" ... does this mean if the IR reads 70degC, it could well be 140degC on the battery? That's hazardous.


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## Power Me Up (Nov 10, 2013)

No - he's talking about internal resistance.

I suspect that the figures are just around 35 milliohms higher than they should be rather than being a multiple.


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## austinios (Nov 10, 2013)

Oh ... thank you for clarifying.


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## Norm (Nov 10, 2013)

Power Me Up said:


> No - he's talking about internal resistance.
> 
> I suspect that the figures are just around 35 milliohms higher than they should be rather than being a multiple.


That's what I'm seeing, which for my new Eneloops works out to be around double.

Norm


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## Floating Spots (Nov 17, 2013)

My app just pulled own a new firmware. This must be decoupled from the actual application updates. Wish there was a change log. 

Sent from my Nexus 7 using Tapatalk 4


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## Floating Spots (Nov 17, 2013)

Never mind. I posted that the firmware did not go through the update process when the app updated on mine. Mine showed the correct version, so it was suggested that I just missed the update. It seems to have picked this connection to push the version of firmware that was already loaded. 

Sent from my Nexus 7 using Tapatalk 4


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## shelm (Nov 19, 2013)

Floating Spots said:


> Wish there was a change log.



I heard that they're gonna do that in future.


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## lowks (Nov 19, 2013)

I wonder if the reason behind why the iPhone app does not push firmware updates is because of iPhone's disabled Bluetooth capabilities. If that be the case then the very least it should have informed that there was a firmware upgrade.


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## linc (Nov 19, 2013)

Hello to everyone on this thread 

I have had a skyRC NC2500 for 3 weeks now and have been using it nonstop.
At the moment I am cycling 4 brand new Eneloops , reinserting them between each 
charge/discharge too get a new internal resistance reading each time. In a fully charged 
state they all read between 50-52 milliohms and in a discharged state they all read between 82-85 milliohms.
on some older and very well used Eneloops I'm getting 60-80 charged 80-140 discharged.
I don't seem to be getting the discrepancy in readings between channels that some people here are as far 
a mah readings are concerned but I wonder if that's because I've only used new/good cells so far? 
what sort of milliohm readings are you guys getting? 
On a side note I am using an iPod touch 4 with a cracked glass (annoyingly the Bluetooth doesn't seem to
work on my good iPod touch 4) with my skyRC NC500 and I've had no problems as of yet. so far it's pushed 1 
firmware update on 17/11/2013. That fixed the problem of the trickle charge current automatically going 
back to off no matter what you set it on. Hopefully it now show's DISCHARG capacity after breakin mode is 
complete even If it only showed it on the charger screen! I will update on that!


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## Norm (Nov 19, 2013)

Just checked my phone, I hadn't realized it had already updated.


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## shelm (Dec 9, 2013)

shelm said:


> I would even recommend this procedure for the Maha MH-C9000 for both *AAA *and *AA *sizes.







German manual: http://www.elv-downloads.de/Assets/Produkte/11/1131/113171/Downloads/113171_ladegeraet.um.pdf
Firmware d/l: https://play.google.com/store/apps/details?id=com.technoline2.smartcharge

kudos to myself. i couldn't remember if i had included the above note in my instructions for the nc2500. today i am playing with my C9000 and realizing how easy it is to insert AA cells single-handed with head(+) first but it does inflict wear and tear on the cells butt(-).

So, on the C9000, there is also nothing wrong with 2-hands cell insertion with tail(-) first, and 2-hands cell removal with head(+) first.

i really wrote beautiful instructions. :huh:


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## AleXis6 (Dec 17, 2013)

Power Me Up said:


> 1910
> 1711
> 
> Repeating the test with a different set of 4 Eneloops gave the following discharge capacities:
> ...


I have similar differences. I have writent to support about the issue and asked them how to set oe calibrate the equal sensitivity for all slots.
They answered that from their opinion it is normal differences and not need to correct anything.
Strange - very expensive device, but accuracy is significantly lower than LaCrosse or Maha.


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## Power Me Up (Dec 17, 2013)

AleXis6 said:


> I have similar differences. I have writent to support about the issue and asked them how to set oe calibrate the equal sensitivity for all slots.
> They answered that from their opinion it is normal differences and not need to correct anything.
> Strange - very expensive device, but accuracy is significantly lower than LaCrosse or Maha.



That's a pathetic (and disappointing) response.

I haven't bothered contacting them myself since I figured that they'd expect me to send it back to Hong Kong and it wasn't worth paying for the shipping cost. There's no real reason why they couldn't do something in firmware if this is a consistent problem affecting a lot of units though.


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## shelm (Dec 18, 2013)

New firmware available since Dec 3rd, did you guys notice? Version 0.9.*8*


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## Norm (Dec 18, 2013)

shelm said:


> New firmware available since Dec 3rd, did you guys notice? Version 0.9.*8*



Was that for Android or Iphone? I don't see one for the Iphone.

Norm


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## Floating Spots (Dec 18, 2013)

In post 101, I had app version 0.98 and fw 1.05 on the Android side. Since then, I had a firmware load and I am at app 0.98 and fw 1.09.
What is your Dec 3rd fw version? 

Sent from my Nexus 7 using Tapatalk 4


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## shelm (Dec 18, 2013)

oops maybe my bad.

just this, the webpage says "Dec 3rd" and i was figuring that nobody had mentioned the Dec 3rd update in this thread:

https://play.google.com/store/apps/details?id=com.revogi.smartcharge


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## Infinito (Dec 20, 2013)

Hi guys.

I have a minor problem with the NC2500 charger. Problem lies in connecting to it by bluetooth, with an Android tablet. The tablet is Asus Memopad HD 7, with stock Asus Android installed.

We also have 2 Android phones in house (LG Optimus 4X HD and LG Nexus 4) and they both connect without a problem.
The process that was used on all three devices upon first connection is:

Holding down Enter button on NC2500 for five seconds
Going into Android bluetooth settings, finding the charger and pairing it
Opening the SkyRC application
At this point both phones connected instantly (in a little more than a second), but the tablet never seems to connect. After about 10 seconds I will get some notification, that has two buttons, one of them says "scan other". If I press that I get a spinning wheel and after another 10 seconds it will show something that looks like a MAC address of the charger, but it will never connect.


I also wrote to the support, asking if tablets are maybe not supported and this is what I got back: "NC2500 charger supports both iOS and Android."

BTW, both application on the tablet and the firmware on the charger are up to date. If I forgot to give some additional information, please ask.

Has any of you had a similar problem and solved it?

Thanks for reading through


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## Norm (Dec 20, 2013)

Here's an odd one for you, we had a hot day yesterday, I heard a noise from my office, the fan was running on the NC2500, no cells anywhere near it but it was plug in to a 12V source.

Norm


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## linc (Dec 30, 2013)

Norm said:


> Here's an odd one for you, we had a hot day yesterday, I heard a noise from my office, the fan was running on the NC2500, no cells anywhere near it but it was plug in to a 12V source.
> 
> Norm



I live in Australia QLD and the fan on my NC2500 runs periodically all day long even when it's just pugged in with no cells in it.
(don't know what it dose in the night)


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## digiowl (Dec 30, 2013)

Sorry for jumping in here, but i want to get one clarified.

Can the USB port be used as a "power bank"?

Meaning, is there any ways to use inserted batteries to charge a device without the AC being plugged in?


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## lowks (Dec 30, 2013)

digiowl said:


> Sorry for jumping in here, but i want to get one clarified.
> 
> Can the USB port be used as a "power bank"?
> 
> Meaning, is there any ways to use inserted batteries to charge a device without the AC being plugged in?



It can't be used in "power bank" mode like XP4. You have to have the AC plugged in.


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## AleXis6 (Jan 14, 2014)

another SKYrc's bag after december FW update.
allways charger is starting charge with *0,3A for AA only for slot #2* (1,0 for another slots).
and it is impossible to change this setting (I know where this parameter in the menu, but it doesn't remember my setting).


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## Floating Spots (Jan 14, 2014)

Mine remembers the current set last in the app. It seems to remember this even through a short power cycle. 

Sent from my Nexus 7 using Tapatalk


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## Almighty1 (Jan 18, 2014)

My question is has anyone tried the C/D adapters on this and does it work?

Also, it seems the competition, the Maha C9000 and the BT-C2000 both have a 20,000mAH capacity versus the 3,500mAH limit on this one, I wonder if they can increase it in firmware?


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## Šokre (Oct 9, 2014)

As android phone owner i wonder how good is application for this charger updates often and how is support for charger from manufacturer ?


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## AleXis6 (Nov 4, 2014)

Šokre said:


>


Software and FW sometimes updated, not often. Support is not flexible and friendly


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## magellan (Nov 8, 2014)

I really like it and have both the Opus and Maha but the powerful Bluetooth app is great and tips the scale in its favor.


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## Ferdinando (Jan 28, 2015)

Maybe someone can help me to understand.

I have charged 4 Eneloop AAA (at this moment I don't remember exactly the model, they are white with ENELOOP written in blue) with this charger.

500 mA charging current, no trickle, max voltage 1.50V.

with other bulk AA Ni-Mh 2500 mAh I have the dv/dt
termination; with Eneloop I have seen the
max voltage termination.
It is a normal behavior with Eneloop ?

Sorry I am not so much expert about Ni-Mh.


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## HKJ (Jan 28, 2015)

Ferdinando said:


> Maybe someone can help me to understand.
> 
> I have charged 4 Eneloop AAA (at this moment I don't remember exactly the model, they are white with ENELOOP written in blue) with this charger.
> 
> ...



Yes it is, if you check my reviews you will see most chargers uses voltage termination for white eneloops, the black eneloops are more likely to terminate on -dv/dt.
With the sky charger you can raise the termination voltage a bit and get -dv/dt termination, I tried that in my review of the charger.


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## Ferdinando (Jan 28, 2015)

HKJ said:


> Yes it is, if you check my reviews you will see most chargers uses voltage termination for white eneloops, the black eneloops are more likely to terminate on -dv/dt.
> With the sky charger you can raise the termination voltage a bit and get -dv/dt termination, I tried that in my review of the charger.



Thanks HKJ.
I've read a lot of your reviews, even the NC2500 review.
And I remember your annotation about the -dv/dt termination on NC2500.
With my bulk Ni-Mh, usually when I set 1.5V of voltage termination, I have the -dv/dt.
For this matter I've been surprised.

Here I have read that exist also the dT/dt termination, where the temperature sensor is required.
Instead it seems that the -dV/dt does not require the temperature sensor.
I am a bit confused about.
Sayng -dV/dt does not involves the temperature measure ?


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## HKJ (Jan 28, 2015)

Ferdinando said:


> Thanks HKJ.
> I've read a lot of your reviews, even the NC2500 review.
> And I remember your annotation about the -dv/dt termination on NC2500.
> With my bulk Ni-Mh, usually when I set 1.5V of voltage termination, I have the -dv/dt.
> ...



Letters:
t=time
T=temperature
V=Voltage (V is correct, but i am often lazy and writes v).
d=delta, i.e. variation

-dV/dt is a negative voltage variation over time, with old batteries or low charge currents this can be difficult to detect.
dT/dt is a positive temperature variation over time, due to ambient changes and heat from the charger it can be difficult to get reliable.

The best chargers will check for both and a couple more indicators for end of charge.


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## magellan (Jan 28, 2015)

Almighty1 said:


> My question is has anyone tried the C/D adapters on this and does it work?
> 
> Also, it seems the competition, the Maha C9000 and the BT-C2000 both have a 20,000mAH capacity versus the 3,500mAH limit on this one, I wonder if they can increase it in firmware?



Yes, they work fine. 

I really like this charger/analyzer and especially the Bluetooth remote app. I have most of the quality charger/analyzers out there but this is my fave for NiMH. It beeps and notifies you when a battery is finished charging, among many other functions, which saves a ton of time when recharging lots of AAA's because you don't have to keep checking the LEDs.


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## Ferdinando (Jan 28, 2015)

magellan said:


> Yes, they work fine.
> 
> I really like this charger/analyzer and especially the Bluetooth remote app. I have most of the quality charger/analyzers out there but this is my fave for NiMH. It beeps and notifies you when a battery is finished charging, among many other functions, which saves a ton of time when recharging lots of AAA's because you don't have to keep checking the LEDs.



Can you suggest me a shop where buy such C/D adapter for MAHA and NC2500 ?
Many Thanks.


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