# Test/Review of Charger Opus BT-C2000



## HKJ (Nov 19, 2013)

[size=+3]Charger Opus BT-C2000[/size]















This charger is new on the market, with a design that looks very much like the BM200 charger. This is because the charger is an improved version of the BM200. I have not tested the BM200 and will not be able to say exactly what improvements it has.





















The charger comes in a cardboard box with a little explanation about the charger on the outside.






Inside the box is the charger, a power supply, two C/D cell adapters and a manual.
The power adapter I got is the EU version, it has universal voltage 100-240VAC 50/60Hz and delivers 12V 1.5A.






When the charger is turned on, it first displayes the formware version (2.0 for the tested charger), then does a display test where all the text can be seen. 
When the text is blinking , it is possible to select mode:


CHARGE: Charge battery with 200 to 1000 (1400)mAh.
DISCHARGE: Discharge battery with 100 to 500 (700)mAh.
DISCHARGE REFRESH: Discharge and charge the battery 3 times.
CHARGE TEST: Charge, discharge and charge the battery, show how much current was discharged.
QUICK TEST: Measure the internal resistance of the battery.

After having selected mode, it is possible to select current.
When putting multiple batteries in the charger at the same time, it is possible to select mode and current simultaneous for all of them (Very nice).

When charging or discharging it is possible to use the DISPLAY button to select between V, mA and mAh (Can be Ah for large cells).






When the slots in the charger is empty, the display will show "null".






Here is an example where I have selected different functions for each slot.






Each time a button is pressed, the light turns on for a 30 seconds.






The charger uses an external 12 volt power supply (Specified input voltage range is 10V to 16v).






The charger has two minus connection points, but they are not used to select default charging current, it is always 400mA. The metal at the side is probably a temperature sensor.









AAA is placed very low in the charger, the AA has more air around them.
The slots are not equal, slot #1 and #4 can charge and discharge with higher current, but only if slot #2 and #3 are empty.
I.e.
Using *only* slot #1 and/or #4, the maximum charge current is 1400mA and maximum discharge current is 700mA.
In all other cases the maximum charge current is 1000mA and maximum discharge current is 500mA.









The included adapter are for use in slot #1 and #4 and makes it possible to charge/discharge C and D cells (Notice that internal impedance will give wrong result if used with these adapters).









Here is the adapters with a C and a D cell.
Remember to select higher current when charging/discharging C/D cells, or it will take a *long* time.
















[size=+2]Measurements[/size]



The LCD background light turns off 30 seconds after the last keypress.
Discharge battery with less than 0.1mA when power is disconnected.
Charge battery with about 15mA when power is connected and charge cycle is done.
Charge will restart charging after power loss or battery insertion. 
The volt display matches my DMM within 0.02 volt when current is off.
The voltmeter will measure from 0.2 to 1.8 volt and probably more.
The current display shows a slightly high value when charging, I got 998mA on display and 982mA with a DMM and a cold charger.
The current display shows a slightly low value when discharging, I got 501mA on display and 507mA with a DMM and a cold charger.







The charger cannot really sustain the 1400mA charge current, it might be due to heat that it reduces the charge current (It has temperature sensors both for the electronic and the batteries) or it might be because it cannot drive the full current when the battery is nearly full.
The termination looks fine.










Slot #2 and #3 can only do 1000mA charge current, here the current is constant all the time.






Slot #4 can also charge with 1400mA and it also reduces current.






The eneloop XX has more capacity and takes longer to charge. The termination looks fine again.






With AAA I uses the default 400mA charge current.






Testing with a D cell did also work (This cell has more than rated capacity).






A 2000mAh eneloop at 400mA, forgetting to select charge current means 5½ hour charging time, instead of 2 hours.
The charger terminates perfectly, even with this low charge current, this is very good.






Doing a charge refresh shows the 3 cycles.






The charge test with a charge, a discharge and a charge again.






A simple discharge.






The charger can spot a full cell in 6 minutes with 1000mA charge current.






All slots together with 1000mA charge current. The thermo probe is on the battery in slot #3.






With two batteries and 1400mA charge current the temperature is much lower, there are two reason for that: the total current is lower and I did measure at slot #4.





M1: 40,4°C, M2: 46,3°C, M3: 47,0°C, M4: 40,6°C, HS1: 64,3°C

The two batteries in slow #2 and #3 receives most heat from the charger, as can be seen on the temperature.
Note: This test was done at 1000mA charge current, using a lower charge current will also lower the temperature.





M1: 36,5°C, M2: 45,8°C, M3: 46,3°C, M4: 39,4°C, HS1: 63,8°C

With a thermo camera it is very obvious where the energy goes when testing a discharge.






The charger uses a fixed charge current and uses pwm to adjust the actual charge current.
At 200mA the duty cycle is about 13% (It might change with battery voltage).
The pwm frequency is 33 Hz.






At 400mA the duty cycle is about 30% (It will probably change with battery voltage).






At 1000mA the duty cycle is about 77% (It will probably change with battery voltage).






The charger cannot reach the full current when I have connected the oscilloscope. This is because I has a 0.1 ohm resistor in series with the battery and this means the charger must supply 0.14 volt extra.






Discharge is also done with pwm. Here using a duty cycle of 87% to discharge with 500mA.






As expected the quick test is a couple of puls loads.
The Quick Test showed 0.167 ohm with the resistor and 0.064 ohm without resistor (The 0.003 difference is due to connections and tolerance on the resistor).


Testing with 2500 volt and 5000 volt between mains and low volt side on power supply, did not show any safety problems.



[size=+2]Conclusion[/size]

The charger has a lot of functionality and does a good job with charging and analyzing. The user interface is easy enough to use, but requires a few tries and some reading in the manual to really know what is going on (It is a bit difficult to guess that "discharge refresh" means 3 cycles). 
I believe this is a good NiMH charger/analyzer.



[size=+2]Notes[/size]

The charger was supplied by DanaCo for review.

Here is an explanation on how I did the above charge curves: How do I test a charger


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## austinios (Nov 19, 2013)

I'm keen to understand how this charger sets itself apart from the C9000 and perhaps the NC2500. Based on price point, they may not be differentiated much. C9000 has set the bar for the last few years and considered to be the charger/analyzer to beat. NC2500 attempts to match that performance and incorporating in their design, cooling fan to keep overall temperature down when charging. In addition, it has thrown in features that differentiates itself from C9000 like bluetooth connectivity for battery analysis and usb port for mobile device charging. 

The CT2000 may have made some usability improvements over the BM200 (in navigating through the menu options). The CT2000 claims material and design improvement over the BM200 and looks to be the "final prototype" (after BM100, BM200, and even possibly BM210). But since they are claiming a new design over the BM200, I can't help but feel that this could be a "new prototype" that will possibly soon see "newer improvements". In fact, I am seeing CT3000 and CT3100 in some ads but may not be marketed under the OPUS banner.


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## HKJ (Nov 19, 2013)

austinios said:


> I'm keen to understand how this charger sets itself apart from the C9000 and perhaps the NC2500.



Without having tested them it is difficult to say.
I do have the C9000 and has used it for a long time, but I have never put it on the test bench.

The C2000 is supposed to be better for marginal batteries, but as you can see in my review I have not tested this.
The internal resistance may be a very interesting function, that makes it possible to spot bad batteries very fast. If somebody got the C2000 and some old batteries, it could be interesting to see IR readings.


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## kreisl (Nov 19, 2013)

HKJ said:


> Without having tested them it is difficult to say.
> I do have the C9000 and has used it for a long time, but I have never put it on the test bench.



I don't have the C2000 so i cannot compare the 2 chargers head to head like this:



since the C9000 shows *accuracy *in the readings for every channel, do a Refresh&Analyze (always 1.0A charge rate, -0.5A discharge rate) on all your Eneloop AA's repeated times until the capacities don't change anymore. then pick the 4 cells which have the same capacity and label them in order, say (#1:1960/#2:1962/#3:1965/#4:1971)mAh. do a final R&A on these 4 cells to confirm that they are indeed the ~same capacity and that their resting time in the C9000 is identical. C9000 applies trickle charge afaik when the cells are left in the charger after completion of the R&A program and the top-off charge. after hours of trickeling the 4 cell voltages will settle to a steady-state voltage in correspondence to the trickle charge. the cells are now *e*qually *c*onditioned and *p*erfect *r*eady for the tests (_ECPR_) 
quickly remove the cells from C9000 and quickly insert them in C2000 and start the DISCHARGE program at -0.5A. after program completion take note of the discharged capacities and evaluate:
The readings should be the ~same (or at least in the same ascending order, i.e. #1<#2<#3<#4) to indicate *consistency*. If they aren't, then there is hardware variation between the four C2000 channels. 
The readings should coincide with the C9000 reference values. If they don't, then there is software discrepancy between C2000 and C9000. 
 
recharge the cells in C9000 at 1.0A and leave them in the charger for many hours to get back to _ECPR_ 
repeat: go back to 2., i.e. DISCHARGE at -0.5A. The readings should be ~equal to 2. to indicate *reproducibility*. If they aren't, then repeat 3. and 4. again to confirm that the C2000 lacks reproducibility. 
to confirm hardware variation between the four C2000 channels, simply 'rotate' the cell configuration in the C2000 for the DISCHARGE program and compare the results. if you don't know how to interpret the results, then change the C2000 cell config once again and discharge to collect even more confusing data lol 
once you have established to which degree your tested charger, here: 1 sample of C2000, gives consistent AND reproducible AND accurate readings and you are satisfied, recharge the cells in C9000 at 1.0A for the last time and leave them in the charger for many hours to get back to _ECPR_, then do a concluding DISCHARGE at -0.5A in the very C9000. Since the C9000 is accurate and you've been using Eneloop AA, you should get a reading close to 1., maybe (#1:1958/#2:1961/#3:1967/#4:1969)mAh. Done. Perfect score for the C9000!, and you can calculate your own score for the C2000. 

Simple but effective testing methodology to compare capacity readings between chargers and between the channels of a charger. It is not even necessary to check the voltage of _ECPR_. The whole testing takes up a lot of time (days!) because of the time to reach _ECPR _and because of the *repeated *test runs to establish *data integrity*. A room with constant temperature is required too 

To me the above methodology sounds logical and fail-safe. If you believe that something stinks or i am wrong, lemme know, thanks. :thumbsup:


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## candle lamp (Nov 20, 2013)

Another excellent test review. HKJ! 
Thanks a lot for your effort and time as always. :bow:

There is _"The included adapter are for use in slot #1 and #4 and makes it possible to charge/discharge C and D cells (Notice that internal impedance will give wrong result if used with these adapters)" _in your review.
Could you please explain in detail?


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## HKJ (Nov 20, 2013)

candle lamp said:


> There is _"The included adapter are for use in slot #1 and #4 and makes it possible to charge/discharge C and D cells (Notice that internal impedance will give wrong result if used with these adapters)" _in your review.
> Could you please explain in detail?



Internal resistance is very low ohmic values, because the adapter adds two more connections and some short wires, the value will be too high and you will see more variation in the value, due to the connections (The resistance of a connection will often vary).


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## kojack6319 (Jan 8, 2014)

Excellent review HKJ!

It's a little disappointing that the 1400mA cannot be sustained in any of the examples you show. Maybe it's the algorithm. As you noted, the temp is lower with two cells @1400mA than four cells @1000mA. So, a thermal reason doesn't seem likely. The lower charge rates were maintained in your examples, even the [email protected] with higher temps. It would be interesting to see if the MH-C9000 maintains it's higher rate throughout the charge. Perhaps with all the C9000 info here on CPF it has been shown.

C & D charging/analyzing on a smart charger is a welcome idea but it seems to fail here with unreliable variation in values. This can lead to premature charging'discharging termination due to higher contact resistance and the resulting capacity numbers are unreliable. 

All-in-all, this might be a nice addition to the MH-C9000, especially for AAA cells, but not a replacement.


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## HKJ (Jan 8, 2014)

kojack6319 said:


> It's a little disappointing that the 1400mA cannot be sustained in any of the examples you show.



My guess is that it is a voltage limit, the charger can only sustain 1400mA up to about 1.45 volt.



kojack6319 said:


> C & D charging/analyzing on a smart charger is a welcome idea but it seems to fail here with unreliable variation in values. This can lead to premature charging'discharging termination due to higher contact resistance and the resulting capacity numbers are unreliable.



I would not worry about the connection resistance when analysing capacity, a couple of mOhms is not going to affect that result much at 700mA discharge current.


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## IT_Architect (Feb 13, 2014)

HKJ said:


> The charger has a lot of functionality and does a good job with charging and analyzing. The user interface is easy enough to use, but requires a few tries and some reading in the manual to really know what is going on (It is a bit difficult to guess that "discharge refresh" means 3 cycles).
> I believe this is a good NiMH charger/analyzer.


I wish you could review the La Crosse BC-1000 using the same methodology so we could compare them.


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## HKJ (Feb 13, 2014)

IT_Architect said:


> I wish you could review the La Crosse BC-1000 using the same methodology so we could compare them.



I do not expect to, but maybe the new BC-1020


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## cwray2014 (Feb 17, 2014)

> "Using *only* slot #1 and/or #4, the maximum charge current is 1400mA and maximum discharge current is 700mA.
> In all other cases the maximum charge current is 1000mA and maximum discharge current is 500mA."



Thank you for your review of the BT-C2000. It provided needed clarification not found in the Operating Instructions. The Opus provided documentation is basic, so I appreciate your thorough analysis. The graphical analysis is very helpful. Curious why the maximum charge and discharge is limited to slots #1 and #4 only. Cost consideration I suppose. Unit is reasonably priced as is. Perhaps future versions will permit maximum charging/discharging in all slots.


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## RI Chevy (Feb 17, 2014)

Welcome to the Forum! :welcome:


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## gbuyer (Mar 9, 2014)

May I say BT-C2000 is the ultimate charger? I am considering buy a MH-C9000, but it seems it is better to wait :naughty:


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## HKJ (Mar 10, 2014)

gbuyer said:


> May I say BT-C2000 is the ultimate charger?



Not more than other analyzing chargers:
MH-C9000
BT-C3100
SKYRC NC2500
BCxxxx

Until now I have only tested the BT-C2000 & BT-C3100, but I will be testing more.


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## johnmeyer (Mar 20, 2014)

I just purchased this tester and like it very much. I have a few questions about operation that I haven't been able to answer just by using it. 

1. When using "Discharge Refresh" or "Discharge Test," I can set the discharge current, but is it also possible to set the charge current independently (i.e., to a number different than the discharge current)? I have tried switching first to "Charge" and setting the charge current there and then changing to one of the Discharge modes, but I don't know if the charge current "sticks" when I change modes.

2. I build battery packs and wanted to test some sub-C and 4/5A cells. I was easily able to electrically connect them, simply by using a spring fitted at the positive terminal. What I can't tell is whether the charger will still be sensing the heat from the battery. Does anyone know whether heat is sensed from the positive and negative terminals; from the metal contacts near the actual contacts; or via some sort of IR sensor buried in the charger case?

I had some 10-year-old, but never used NiMh AAA cells that have been in the fridge, forgotten, for a decade. They are supposed to be 500 mAh cells, but the initial Discharge Test only showed about 40 mAh of capacity. I did one Discharge Refresh cycle and that got the cells up to about 200 mAh. However, because I couldn't figure out how to independently set both charge and discharge currents, I instead did a discharge using a really high current, followed by a charge using a really low current. I then tried again, this time using a low current, and then higher charge current (about 0.8C). I then tried the remaining variations. However, I realized that I don't know which combination might be the most effective for resurrecting a cell that is old, but has not been used much.

Thanks for any help anyone can provide!


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## Turak (Mar 20, 2014)

I too have a new BT-C2000 and have been testing it a bit.

As for the Charge/Discharge functions/selections.....it behaves like the BC700/BC900/BC1000 series chargers.

Meaning that your *'charge current' is always 'double' your 'discharge current'*.

Or you can think of it the other way around, your *'discharge current' is always 'half' of your 'charge current'*.

*You CANNOT set them independently of each other. When you set one, it automatically adjusts the other.*

So.... When you insert a battery and select *'Discharge Refresh' *and then you select a discharge current of 100, 200, 300, 400, 500, or if using the outside slots 600 or 700, your charge current will be double ( i.e. 200, 400, 600, 800, 1000, 1200, or 1400) the discharge rate you select. See table below.

Let's say I insert a battery, select *'Discharge Refresh' *and then select 500 mA as my discharge rate. It will proceed to discharge the battery at 500mA, then charge the battery at 1000mA. It will do it 3 x. I have to double check this one as far as when it finishes...whether it displays the 'discharged' capacity of the cell (useful) or the mA accumulated during charging (useless). If you do not select a discharge rate, it will default to 200mA, which means a charge rate of 400mA. Here the BCxxxx series charges are better, in that they will repeat the process up to 20x checking the capacity each time and only proceeding if it increases each time. The BT-C2000 just seems to do it 3x no matter what and seems to just remember the last cycle.

If you insert a battery and select *'Charge Test' *and then select a charge rate of say 800mA. It would proceed to charge the battery at 800mA until full, then discharge the battery at 400mA, then charge it again at 800mA. At the end it would display the 'discharged' capacity of the battery, which is exactly what you want. If you do not select a rate, it will default to a 400mA charge rate, which means a 200mA discharge rate.

Charge / Discharge
200 / 100
400 / 200
600 / 300
800 / 400
1000 / 500
1200 / 600 (outside slots only)
1400 / 700 (outside slots only)

As far as refreshing your old batteries. I always start off very gentle and work my way up. Since you said they were only 500mA batteries, I would recommend the 200mA charge / 100mA discharge for 1 or 2 Discharge Refresh cycles. That would mean a total of 3 or 6 discharge/refresh cycles. Then if the capacity has improved, move up a little. I probably wouldn't go higher than 400mA charge/200mA discharge as they will probably get quite hot if you try to. Trying to hit them too hard right off the bat, can cause a variety of bad things (overheating, hot spots, separator thinning, etc.) to happen inside them, none of which would be good for them. Sometimes it helps to run a few charge discharge cycles on them. Then let them set for a day or 2, then run a few more charge/discharge cycles. The bad thing is that even if you can manage to nurse them back up a bit near their original capacity, they probably will not really perform like a newer cell, and they may have a very limited number of cycles before they are too far gone.

For sensing the 'heat'.... see the little metal strip by the negative end of each battery slot, on the side. That is connected to a thermistor inside and senses the heat of each battery. It has a sensor for each battery and supposedly 2 on the motherboard...for a total of 6 heat sensors. So...unless your battery is actually touching that little metal strip, it will not be able to sense it overheating.

FYI.... I am currently doing some basic testing comparing its accuracy as far as discharging to a CBA II and an MH-C9000. I want to see how accurate the 3 are compared to each other when it comes to determining the capacity of a battery. So far I am extremely impressed at the accuracy of the CBA II compared to the MH-C9000. (within a couple/few milliamps of each other during discharges). Checking the BT-C2000 now.

Note - Should have my BT-C3100 within a week or 2. Will be doing some serious battery testing with it as well, especially Lithium battery capacity testing on some of my 'surplus' 18650's.

Hope this helps....


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## johnmeyer (Mar 20, 2014)

Excellent answers. Thanks. 

So, the Charge/Discharge ratio is 2:1, hard wired. You also answered a question I forgot to ask, namely whether the mAh reading at the end is for the charge (which is useless, as you noted), or the discharge, when doing the "Discharge Refresh." I didn't know that other chargers remember the previous capacity reading, when doing multiple charge/discharge cycles, and only keep repeating if some improvement is noted. 

That is a good idea. 

As for actually being able to rescue the old batteries, I don't have high expectations, but I thought it was interesting to try because these were brand new batteries, still in the blister pack. With NiCd batteries, I actually built a high voltage "zapper" that is basically a strobe light circuit that dumps its charge into the battery instead of into a strobe light. It does a great job getting rid of the "whiskers" that develop in older NiCd batteries. However, as you pointed out, batteries that have been "rescued" often don't perform well for very long, although my experience with NiCd is that if you drained them quickly (e.g., in a headlamp) and recharged them right away, they were often as good as new. However, once they sat around for a few weeks, they went bad again. 

It is amazing that the charger can sense much heat through those metal strips because they don't seem to be in very solid contact with the AA or AAA battery. When using the C/D holder, the temperature transfer must be even less. I'll keep this in mind when I use the charger to refresh some of these old, odd-sized battery pack cells because they don't make contact with the charger enclosure in the same was as the AAA/AA/C/D batteries do.

Finally, I'll be interested to hear your experience with the BT-C3100 tester. I saw the reviews, but couldn't find any place to buy it. I don't have any Li-ion batteries at this point, so I wasn't too disappointed not to be able to get it. It does seem like the most versatile of the 3-4 testers that always seem to be mentioned in various reviews. 

Oh, one quick question: since you obviously have charged a lot of batteries, do you have an "ideal" charge rate for Eneloops that would yield the longest life? Absent any other information, I was going to charge mine at 0.3C. It seems that using a lower current might make it difficult for the charger to calculate the correct cutoff, and anything much over 0.5C might start generating too much heat.


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## Turak (Mar 21, 2014)

Take a read on the other thread regarding the proper charge/discharge rate for an eneloop....in particular my post near the end.

http://www.candlepowerforums.com/vb/showthread.php?240121-Appropriate-Charge-Rate-for-NiMH-Batteries

Generally speaking go as high as you can as long as the batteries are not getting HOT. Warm is OK. Hot is NOT.

I would not hesitate to do 1A on newer batteries, but if they start coming off hot, go down a bit.


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## johnmeyer (Mar 21, 2014)

Thanks! I've read dozens of posts here and elsewhere about NiMH in general and Eneloops in particular. From those posts it is pretty clear that when using a smart charger, 0.5C to 1.0C is the range which provides the best compromise between achieving a full charge in a reasonable amount of time, while not degrading the battery, thereby achieving a maximum number of recharge cycles and only minor degradation in capacity as the battery ages. However, even though the subject of Eneloop charging has been well-covered elsewhere I thought I'd ask again here because clearly the people here have lots of personal experience that they can add to what is stated in various spec sheets, including those provided by Sanyo/Panasonic in their Eneloop datasheets.


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## alxuy (Jun 28, 2014)

Sorry for the noob question, but this is my first "pro" battery charger. How do you know how much charge a battery has on it? When I insert a battery on the charger it shows 1.34v and when I use the Quick Test option it shows a number like "50".....what that it means? there´s no easy way for the device to display something like "1850 maH" so I can do the math if we are talking about a 2000 maH battery and say "oh, great, this battery is at 90%" or something like that? I apologize for my poor english, my native language is spanish. TIA Alx


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## HKJ (Jun 28, 2014)

alxuy said:


> Sorry for the noob question, but this is my first "pro" battery charger. How do you know how much charge a battery has on it? When I insert a battery on the charger it shows 1.34v and when I use the Quick Test option it shows a number like "50".....what that it means? there´s no easy way for the device to display something like "1850 maH" so I can do the math if we are talking about a 2000 maH battery and say "oh, great, this battery is at 90%" or something like that? I apologize for my poor english, my native language is spanish. TIA Alx



You cannot do a quick test, but when you put a battery into the charger hold down the MODE button for a second or two, then select CHARGE TEST and select some current. Next day (Depending on what current you select and on battery) you can see the capacity on the charger.


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## RI Chevy (Jun 28, 2014)

Welcome to the Forum! :welcome:


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## alxuy (Jun 28, 2014)

Thanks for your answer and for your warm welcome! 
I was also checking in another forum and the Quick Test option is to measure the Internal Resistance of the battery.......for what I understood, if that number is below 100, the battery is ok, if it is above that value it will not support too much charge and it cannot be used for very demanding devices like cameras, flashlights, etc.....is that correct?
Another silly question.......the batteries says they are 1.2v.......but when I insert a AA battery in the charger, sometimes it says 1.4v, 1.32v, etc.......shouldnt it always says 1.2v? what´s the meaning of that? 
Sorry for the noob questions again.
Alx


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## HKJ (Jun 29, 2014)

alxuy said:


> Another silly question.......the batteries says they are 1.2v.......but when I insert a AA battery in the charger, sometimes it says 1.4v, 1.32v, etc.......shouldnt it always says 1.2v? what´s the meaning of that?



The voltage from a battery is not constant. When it is fully charged the voltage is highest and when the battery is empty the voltage is lowest. On rechargeable batteries the convention is to print some average voltage.


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## alxuy (Jun 29, 2014)

Let me see if I get this right......If I discharge a battery and the displays shows 757mah, that means the total amount of charge that was removed from the battery were 757mah, right or wrong?
But when I did this, why I was still able to put the battery on a radio and the radio was still working with it? It supposed to be discharged, no?
I have another non-intelligent charger that has the DISCHARGE function as well, and when it discharges the battery, it left it completely empty. Is that BAD for the battery or would you recommend me to use that non-intelligent device to discharge all the batteries around and then use the BT-C2000 to do a full charge?

And .....if I have 4 2700mah batteries, which I could charge at near 2500 mah, but after I put them on an old walkman after a few days it stops working, that would mean that some of those batteries are damaged, right? how would you know which is/are the BAD one/s? just putting all of them in the charger and reading each´s Voltage?


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## HKJ (Jun 29, 2014)

alxuy said:


> Let me see if I get this right......If I discharge a battery and the displays shows 757mah, that means the total amount of charge that was removed from the battery were 757mah, right or wrong?



Correct.



alxuy said:


> But when I did this, why I was still able to put the battery on a radio and the radio was still working with it? It supposed to be discharged, no?



The radio will probably only work for a short time. The battery is discharged, but only down to about 0.9 volt and it will recover some voltage when discharge removed stops.



alxuy said:


> I have another non-intelligent charger that has the DISCHARGE function as well, and when it discharges the battery, it left it completely empty. Is that BAD for the battery or would you recommend me to use that non-intelligent device to discharge all the batteries around and then use the BT-C2000 to do a full charge?



Depending on the battery, it can be bad for the battery.



alxuy said:


> And .....if I have 4 2700mah batteries, which I could charge at near 2500 mah, but after I put them on an old walkman after a few days it stops working, that would mean that some of those batteries are damaged, right? how would you know which is/are the BAD one/s? just putting all of them in the charger and reading each´s Voltage?



The best way to test them is to do a CHARGE TEST.


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## alxuy (Jun 29, 2014)

Really thanks for your patience sir  I really appreciate that!
2 small questions.
One example from real life. I just finished this procedure with an AAA battery.
Type of battery: AAA
Labeled as: 900 mah
Mode: Charge
Current: 400 mah
Time: 1h45m
Final V: 1.44
14 mV (don´t know what this is)
Final current: 695 mah
Quick Test: 83

what can you "read" from this?...is it in good shape or not?... would you recommend to do a Discharge Charge cycle?.....

And question #2.......removed the previous battery from question number #1 and inserted another one (same features, 900mah, but 1.25v) and tried to do a CHARGE TEST the charger only displayed "----" ....what those 4 "-"´s means? is the device doing anything in the background? because after 10 minutes is still showing the same?

Alx


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## HKJ (Jun 29, 2014)

alxuy said:


> Labeled as: 900 mah
> 
> Final current: 695 mah



Without a measurement on the battery as new it is difficult to say, but if it did have 900mAh as new, it is starting to get old with only 700mAh left.
It can still be used, but preferable in devices that do not draw high current.




alxuy said:


> And question #2.......removed the previous battery from question number #1 and inserted another one (same features, 900mah, but 1.25v) and tried to do a CHARGE TEST the charger only displayed "----" ....what those 4 "-"´s means? is the device doing anything in the background? because after 10 minutes is still showing the same?



I do not remember the four "----", but it probably means that the battery failed, i.e. it is to old (Or you have a bad connection to the battery i.e. try a few times more and see if you get the same result).


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## alxuy (Jun 29, 2014)

I don´t think is a bad connection because it could read it´s voltage (1.25v) at the beginning just fine. Now I put it in DISCHARGE mode (400mah) and got stuck in 191 mah and is not moving anymore............can I assume that it´s dead?


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## HKJ (Jun 29, 2014)

alxuy said:


> I don´t think is a bad connection because it could read it´s voltage (1.25v) at the beginning just fine. Now I put it in DISCHARGE mode (400mah) and got stuck in 191 mah and is not moving anymore............can I assume that it´s dead?



A bad connection is not the same as a broken connection, it can also just have higher resistance. This will allow reading of voltage, but not charge test.
The discharge mode shows how much current in left in the battery, it cannot be used to evaluate the capacity of the battery, except if you have charged it fully before testing. This is combined in CHARGE TEST


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## alxuy (Jun 29, 2014)

I see, I see. Well, I´ve used the non-intelligent charger and discharged it completely and put it back on the BT-C2000 and the quick test displayed 8888 but I´m gonna try to charge it anyways. I´m thinking maybe is a good idea to create a file per battery (I have like 30 rechargable batteries between AA´s and AAA´s) to keep a record of each one after every new charge, to see how can I combine them if I need to use them for my camera´s or for my low drain devices. Hey, do you if there´s an application to do that? that would be a great idea (I know we can use Excel for that, but I´m just lazy, haha)
By the way, HKJ, thanks for all the time that you´ve taken to answer all my newbie questions, really appreciate it man  I hope this helps other new users in the future, in fact, I would recommend this forum to all my friends (like I´m recommending this battery charger too)
Regards,
Alx


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## HKJ (Jun 29, 2014)

alxuy said:


> I´m thinking maybe is a good idea to create a file per battery (I have like 30 rechargable batteries between AA´s and AAA´s) to keep a record of each one after every new charge, to see how can I combine them if I need to use them for my camera´s or for my low drain devices. Hey, do you if there´s an application to do that? that would be a great idea (I know we can use Excel for that, but I´m just lazy, haha)



I do not know of any apps, but I have seen some spreadsheets designed for keeping track of batteries here on cpf.


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## dc38 (Jul 26, 2014)

Thought I might state that eneloops are a super tight fit in this charger, version 2.1...it leaves denting and scratching on the batteries.


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## StandardBattery (Sep 29, 2014)

The BT-C2400 version of this charger is on amazon right now for $17. That's a steal! This version does not come with the C/D adapters but otherwise is the same apparantly. Not sure if hat package comes with adapter and car cable or not, but if one needed another NiMH charger kicking around i'd jump on that deal. Maybe they will have a new firmware release and are clearing out old stock, but still good deal.


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## StandardBattery (Oct 3, 2014)

StandardBattery said:


> The BT-C2400 version of this charger is on amazon right now for $17. That's a steal! This version does not come with the C/D adapters but otherwise is the same apparantly. Not sure if hat package comes with adapter and car cable or not, but if one needed another NiMH charger kicking around i'd jump on that deal. Maybe they will have a new firmware release and are clearing out old stock, but still good deal.


Did anyone else grab this deal? It didn't last long.

The BT-C2400 looks like a very good charger, I was a little upset when I missed it at $25, but wow to then get it at $17 was unbelievable. 

I don't have the BT-C2000, but I don't see any reason yet to believe this is not the same charger as that one without the C&D cell adapters in the package. My package also did not include the car adapter, but I believe some packages do.

The charger, like many Opus Chargers, comes in the same basic charger case. You probably cant tell it apart from the BT-C2000 from the front, but the model number is printed on the bottom. The size is also identical to the BT-C3100 for example, but a little different design with the fixed size batery slots for AA and AAA and no fan like the BT-C2000.

On bootup it reported 2.1 the latest version of the software.

Large screen compared to the Lacrosse chargers (e.g. BC-700) which is easier to read, and it is backlit very nicely (disply times out, easy to reactivate).

One person reports that the slots are too tight and can dent battery tails, but might is perfect with Eneloop AA and AAA. 

Reports are it never comes with nice rupper feet, and that was true for the one I received. A little annoying, but not too hard to fix.

400mA default change current for AA

12V 1A Adapter

So basically I think if you see this on sale it's worth getting, especially if it it's on super sale.


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## LetThereBeLite (Dec 14, 2014)

HKJ, thanks for the indepth review.
Any plans to add an update for version 2.1 or the 2400 model? there has been a few mods/fixes to v2.1/2400. 

Thanks.


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## HKJ (Dec 14, 2014)

LetThereBeLite said:


> HKJ, thanks for the indepth review.
> Any plans to add an update for version 2.1 or the 2400 model? there has been a few mods/fixes to v2.1/2400.



Not at the current time.


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## appliancejunk (Feb 24, 2015)

dc38 said:


> Thought I might state that eneloops are a super tight fit in this charger, version 2.1...it leaves denting and scratching on the batteries.



Anyone else finding this to be the case?


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## straightShot (Feb 24, 2015)

appliancejunk said:


> Anyone else finding this to be the case?



I always press the negative side in first as this is the spring side and have never noticed a problem with any sort of denting or scratching of the batteries. The fit is tight once the battery is positioned for charging, and that's how I want it.


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## appliancejunk (Feb 25, 2015)

Ok, was a little concerned as I had just ordered one. Got it today and I would say the pressure on the batteries when inserting them feels just right to me. 
This is my first smart battery charger. I'm very impressed by it so far. It's really cool to have the digital readout and all the different option for testing and refreshing the batteries.

Edited to add: I'm also using Eneloop AA & AAA batteries with mine. Along with some older rechargeable I got from the Apple store years ago. Going to see how it will refresh them.

Mine also report 2.1 software and it did have rubber feet on the bottom. No car charging cord.


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## appliancejunk (Feb 26, 2015)

btw, great review!

Question on the Discharge Refresh Mode - discharge and charge the battery 3 times.

Once I start the that mode how do I know where it's at as far as if it's discharging or charging the batteries and if it's doing it for the first time yet, second time or for the third and final time.

How long can I expect it to take on the Discharge Refresh Mode for 4x AA Eneloop batteries?

Also how do I know when it's finally finished?

Thanks,


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## hammerjoe (Feb 26, 2015)

I dont think the charger will tell you any of that. You will have to calculate by time to figure out how long its going to be.

If your eneloops are 2000mAh and you do a refresh at 400mAh then it will take about 5:30 hours to charge and 11 hours to discharge (its always half the charging current) times 3 so about 49 hours altogether (give or take 11 hours because it depends how full the battery is to begin with when it starts with the discharge).

Once its done it should tell you thats its completed.


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## Rockstead (Apr 4, 2015)

Hello,

I recently purchased the BT-C2000 based on the review here and at Amazon.

I have never owned rechargeable batteries before and I'm just lost when I read these threads on how to efficiently charge batteries.

I purchased a few packs of 4th gen eneloops (AA,AAA) and I used them out of the box until they did not have any power left.

Now that I will be charging for the first time ever, I'm just not sure how I should be doing it.

When I place my AA in, it just started charging at 400mah, is that correct? Do I want to be doing it differently so it charges quicker and will there be any negative consequences to that? And when would I be doing all this discharging that I see many people doing?

Sorry in advance for the new questions.


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## RI Chevy (Apr 4, 2015)

Welcome to the Forum! :welcome:

Read over the first post in this thread Fellow member HKJ does an excellent job at explaining how to use this charger. 

You should probably use a higher charge setting for charging AA cells. Either 750 mAh or 1000 mAh (1A). For AAA cells you can use the lower 400 mAh setting. Just read over the instruction manual and post #1 prior to charging. Should be pretty simple and straight forward.


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## johnmeyer (Apr 5, 2015)

RI Chevy said:


> You should probably use a higher charge setting for charging AA cells. Either 750 mAh or 1000 mAh (1A). For AAA cells you can use the lower 400 mAh setting. Just read over the instruction manual and post #1 prior to charging. Should be pretty simple and straight forward.


+1 to that.

I read through a lot of posts, on many different forums across the web, and for LSD (e.g., Eneloop) batteries, 800 mA for AA and 400 mA for the smaller AAA seems to be the most-often mentioned compromise between charging speed, battery stress due to heat, and fast enough charging to activate the end of charge termination sensing. 

If you are in a real hurry, you can certainly use a higher charging current, up to "1C," which means a current that equals the mAH rating stamped on the battery (usually a little over 2,000 mAH for a AA Eneloop). Since this charger can't go that high, you don't have to worry about charging at too high a current for AA. However, for AAA, 1C equals about 800 mAH, and since you can go above that number, you need to be careful when charging those (make sure to _not _set the current for 1,000 mA or higher).

Since I have multiple sets of batteries, I'm almost never in a hurry, and so I always charge AA at 800 mA, and AAA at 400 mA.


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## Cekid (Mar 9, 2017)

what would you choose between opus bt-c2000 and opus bt-c700?

i would like to buy some charger/analyzer, i don't care about lion etc., and i have ended up with the choice between the 2 opus...is there any significant difference between these opus chargers? as far as features go, they are looking almost the same? 

opus bt-c2000 looks like better built device, with better menu buttons...?


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## HKJ (Mar 9, 2017)

Cekid said:


> what would you choose between opus bt-c2000 and opus bt-c700?
> 
> i would like to buy some charger/analyzer, i don't care about lion etc., and i have ended up with the choice between the 2 opus...is there any significant difference between these opus chargers? as far as features go, they are looking almost the same?
> 
> opus bt-c2000 looks like better built device, with better menu buttons...?



I do not remember the difference between them and I do not have time to read my reviews just now 
The larger model usual has an advantage with temperature, because the batteries have more air around them and the charger has more space to get rid of heat when discharging batteries.


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## Cekid (Mar 9, 2017)

@HKJ

makes sense...price difference is couple of dollars anyway....


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