Eneloop Self Discharge study

[Mr Happy]

When I asked if the charging position is critical due to the electrolyte, I would think the discharge position would also be critical. I also said that my camera uses 4 AA cells, two upright & two upside down. Does this mean they are going to discharge differently?

All joking aside, you can be assured to know that there is no free liquid electrolyte in an NiMH cell. The electrolyte is absorbed into a porous membrane and held there by surface tension. It cannot move around under gravity and the orientation of cells in charging or discharging will make no difference.

For reasons that I can't remember at the moment the amount of water included in an NiMH cell is reduced to the absolute minimum with no excess at all. This is why any venting of a cell, for example if it gets too hot on overcharging, is an irreversibly bad thing. There is no surplus of water inside to compensate for any losses.

 

[SilverFox]

Hello Mr Happy,

I have to agree with you... I keep shaking the Eneloop cells I am using for the 15 minute charging cycle testing, and I can't hear any sloshing around at all. Also, there is no "boiling" sounds at the end if the 15 minute charge.

However, I may disagree with you about the gravitational effects on cells. There is some evidence that if a cell is stored for an extended period of time, the electrolyte is effected by gravity. This results in starving part of the separator. This is what causes the cell to heat up if it is charged normally the first time, instead of using the 0.1C charge. The 0.1C charge tries to redistribute the electrolyte evenly throughout the separator.

It takes a long time for this to occur, but after 3 - 4 years sitting on the shelf, it seems to happen.

In normal use this is not an issue, and has nothing to do with normal charging either upside down, laying down, or right side up.

Tom

 

[cy]

finally got several sets of eneloops to try out...

 

[Mike86]

Since I had nothing to do the other day I contacted Sanyo again in response to their comments about the separately packaged batteries having no instructions about charging in an upright position.

They answered "It still implies to when he charges his batteries in another charger."

And their comment "I do not know about other brand of chargers, but it is likely they all say the same thing on their instructions about the batteries not fully charging to their full potential."

I responded that I have two other chargers and neither one has instructions on charging right side up & one is made to lay flat. So how would anyone know it is implied that eneloops have to be charged upright even if used in another charger?

I even gave them an opening for a different answer and suggested that maybe it is their charger's requirement. I said perhaps there is a temperature sensor located at the bottom
and turning it upside down puts the sensor at the top. Since heat rises, the sensor will get hot faster & turn off the charger too early. Could this be the reason?

Here is their response. Obviously their Customer Service dept has no idea and does not care about finding the answer.
------------------------------------------

Sanyo advises to charge in the upright position. It's
suggested to do so because of the following reasons stated
in the previous email.

Best Regards,

Customer Service
Sanyo Energy (U.S.A.) Corp.
http://www.eneloop.com
http;//www.sanyobatteries.com

 

[45/70]

Well, OK. Since I don't have any NiMH/NiCd chargers that are upright, I guess I'm going to have to figure out how to prop them all up somehow, so I can charge my eneloops. :sigh:

Anybody hear anything more about that job opening yet? :thinking:

Dave

 

[TorchBoy]

Re: Eneloop self discharge study

They answered "It still implies to when he charges his batteries in another charger."

Not "applies"?

45/70: You could use the wire stand on the MH-C9000 to hang it on a nail banged into a wall. :naughty:

 

[Unforgiven]

You could always tell them you don't understand and ask for a photo illustration.

 

[Mike86]

Re: Eneloop self discharge study

Not "applies"?

45/70: You could use the wire stand on the MH-C9000 to hang it on a nail banged into a wall. :naughty:

"Implies" is what they said, however "applies" would make more sense. That is if having to charge in an upright position made any sense in the first place.

But I'm still curious why instructions for 3 of their chargers state this.

 

[Mike86]

First of all, I am using eneloops in my digital camera and am happy with them.

But I was still "dancing" with Sanyo about having to charge the cells right side up. I sent them a letter over a month ago & finally got a reply the other day. I have found that sometimes writing a snail mail letter gets a more intelligent response, but not always.

I did mention that the separately purchased batteries made no mention of not charging upside down, that some chargers cannot hold the batteries right side up, and was it perhaps a requirement of their charger.

Sanyo replied: "In regards to your inquiry, it is recommended to charge in the upright position mainly because the liquid inside the batteries will overheat while charging. This recommendation is required for all our chargers and batteries. The Model NC-MQN05 charger with the sliding cover does not interfere with the temperature while charging."

Good or bad, that is an official answer from Sanyo. But I'm just guessing that not a lot of eneloops are getting charged in the upright position and they still are working just fine.

Mike

 

[pobox1475]

After spending a solid month with my new C9000 continuously running break-in's on the cells I had laying around I finally had time to test (break-in) some new Eneloop AA's dated 2006. I know that this may or may not be beneficial to do. I am mostly curious about finding their capacity. Out of the first eight all but one came in at around 1920 mAh and the odd one was 1890. I have read that most users were getting labeled capacity and in some instances almost 100 mAh over. I must say I am a little disappointed, especially with the one that did not reach 1900. Should I run another break-in or refresh on that cell? I don't want it to be a weak link of sorts . Also for future reference what should they be charged at to get the best balance of output and life from them?

 

[Mr Happy]

What's the date on your Eneloops?

Most Eneloops I've tested come in between 1920 mAh and 1980 mAh. They are specified as min 1900, nominal 2000, so above 1900 is within spec.

My feeling is that older Eneloops manufactured in 2006 seem to test a bit lower than newer samples.

I also have a suspicion that the accuracy of the C9000 is not better than +/- 50 mAh per channel.

Lastly, Sanyo's graph of capacity vs. cycles does seem to show a small increase in capacity over the first few charges.

So overall, I wouldn't be too disappointed. The strength of Eneloops lies mostly in areas other than their capacity.

 

[mighty82]

From what I have experienced, the C9000 always shows about 100mAh lower capacity than the bc900 charger. My advanced computer charger agrees with the bc900 on capacity.

 

[TorchBoy]

From what I have experienced, the C9000 always shows about 100mAh lower capacity than the bc900 charger. My advanced computer charger agrees with the bc900 on capacity.

The BC-900 doesn't rest an hour like the MH-C9000 does. The MH-C9000's algorithm more closely follows the IEC standard. What do your advanced chargers do?

 

[riosaeba]

Good Job!
So, if i have understood, the best ni-mh battery is eneloop 2000mah?
I have to use the metz mecablitz 58 with these battery and this mecablitz flash demands a lot of ampere.
Thanks.

 

[Mr Happy]

I have to use the metz mecablitz 58 with these battery and this mecablitz flash demands a lot of ampere.

Hi,

:welcome:

Eneloops are good for lots of amps, so you should have no cause to worry.

 

[EngrPaul]

Good Job!
So, if i have understood, the best ni-mh battery is eneloop 2000mah?
I have to use the metz mecablitz 58 with these battery and this mecablitz flash demands a lot of ampere.
Thanks.

Also consider Imedion 2100 mAh

http://thomasdistributing.com/shop/product_info.php?cPath=122_104_106&products_id=1020&SP_id=68

 

[Anders]

Hello.

Here you can see the difference on high Amperage.




Anders

 

[Turak]

From what I have experienced, the C9000 always shows about 100mAh lower capacity than the bc900 charger. My advanced computer charger agrees with the bc900 on capacity.

There are at least 2 MAJOR reasons that you get about a 50-100mAh difference between an MH-C9000 and a BC900. I actually have 2 of each and love them both for different reasons.

1. Because of changes made to the firmware of the MH-C9000, the charger actually DOES NOT always charge an Eneloop (and others) to its maximum capacity.

The MH-C9000 charger uses -detaV, maxV, and a timer limit for its termination methods. In the early models (F models), the chargers maxV was set much higher and the batteries would actually hit -deltaV.....but the problem was they were getting just a bit too hot. Maha decided to lower the maxV point to 1.47V. THis had the effect of causing many batteries, especially Eneloops, to hit maxV before they hit -deltaV. This in turn causes the Eneloops to come off the charger slightly under maximum capaity. If you check the charts, the Eneloops typically seem to hit -detaV somewhere in the 1.50 to 1.55 range. So ultimately more batteries seem to terminate now by hitting maxV instead of -deltaV with this charger.

The BC900 charger uses the same termination methods and also suffers from the same problem except that it's maxV is set at approximately 1.52V. More batteries seem to terminate by hitting -deltaV than maxV when using this charger. This is also one of the reasons that batteries come off a BC900 a little 'warmer' (besides the fact they are jammed in a smaller space).... they are actually closer to maximum capacity when they hit -deltaV than maxV.

Most 1.5V NiMh AA batteries tend to hit -deltaV anywhere from about 1.45V-1.55V.

2. As stated by someone else, the MH-C9000 rests between the charge/discharge cycles and thus some of the surface charge bleeds away.

 

[SilverFox]

Hello Turak,

You got most of the way the C9000 functions correct, but you forgot to mention the top off charge...

After it terminates the main charge, it charges at 100 mA for 2 hours before droping to its 10 mA trickle charge. Depending on the capacity of the cell, this usually ends up with the cell voltage in the 1.5 - 1.55 volt range and it being fully charged.

A major difference between the BC900 and the C9000 is that the BC900 begins the discharge immediately after charging, and the C9000 incorporates a rest period before discharging.

Tom

 

[DualMonitors]

Hello Turak,

You got most of the way the C9000 functions correct, but you forgot to mention the top off charge...

After it terminates the main charge, it charges at 100 mA for 2 hours before droping to its 10 mA trickle charge. Depending on the capacity of the cell, this usually ends up with the cell voltage in the 1.5 - 1.55 volt range and it being fully charged.

A major difference between the BC900 and the C9000 is that the BC900 begins the discharge immediately after charging, and the C9000 incorporates a rest period before discharging.

Tom

Hi Tom, Turak, et al:

as a newbie, i'm trying to comprehend all this and put it in practical use.

Turak's post seems to indicate that the BC900 charges more "fully" more batteries, which seems like a "good thing".

Tom/Silverfox's post seems to indicate that the C9000 Maha's trickle charge at the end of 100 and then 10mA make the C9000 charge batteries more fully and somewhat more gently, yet still accomplishes the job of a complete charge at the end, even more elegantly so.

Tom's last paragraph of the BC900 beginning the discharge immediately while the C9000 incorporating a waiting period is not immediately clear to me: which is "better"? Is incorporating a waiting period superior? Is beginning the discharge immediately better? Also, is this referring the "refreshing" cycle when one wishes to condition and refresh an old, tired battery?

sorry for the newbie type questions...struggling to understand all this.

thx in advance!