New to Eneloops, initial capacity question

[brianp6621]

So I'm new to the rechargeable scene.

I picked up some AA/AAA Eneloops and the C9000 charger.

So far I've done an initial break-in of 2 sets of AAs with different results.

My procedure was a 100ma Discharge followed by a normal break-in cycle on the C9000.

Set #1 showed an initial capacity of ~2040 mAh while set #2 showed an initial capacity of ~1980 mAh. All the cells in each set of 4 were pretty consistent but the two sets are reasonably different.

The only thing I did differently was when I started the initial set, I first started with the break-in, but about 1 hour or so in (during the initial charge) read an initial discharge can help. So I stopped the charge and did a 400mA discharge. Then very quickly I read that the slowest possible discharge can be more effective so I stopped again and restarted the discharge at 100mA and then everything else progressed normally.

So is the variability I am seeing normal? What should the initial break-in capacity of the Eneloops be (I am reading closer to my first set ~2050 or so I think online).

What should I do to the second set? Cycle them?

 

[Mr Happy]

Hi,

:welcome:

You have made some good purchases.

The results you report seem quite fine. The main thing you are looking for is consistency between cells in a set when treated the same way. That seems to be true with what you have described.

The capacity of Eneloops is not in fact constant, but changes with use. A graph from Sanyo shows the capacity increasing over the first few charge/discharge cycles until it reaches a maximum, then it starts to decline. I would guess that the different treatment you gave the first set of cells is what led to the different capacity measurement.

There is nothing further to do except go ahead and use them.

 

[brianp6621]

Hi,

:welcome:

You have made some good purchase choices.

The results you report seem quite fine. The main thing you are looking for is consistency between cells in a set when treated the same way. That seems to be true with what you have described.

The capacity of Eneloops is not in fact constant, but changes with use. A graph from Sanyo shows the capacity increasing over the first few charge/discharge cycles until it reaches a maximum, then it starts to decline. I would guess that the different treatment you gave the first set of cells is what led to the different capacity measurement.

There is nothing further to do except go ahead and use them.

Thanks,

I made those purchases based largely on this forum. I'm a gadget geek about everything else, why not batteries.

Another question I have is about C/D cells. I just came across the Costco Eneloop pack on Amazon with the C/D spacers.

I'm assuming the main disadvantage here is the Eneloop C/D "cell" will contain much less energy than a standard C/D alkaline or dedicate NiMH cell and will therefore power the corresponding devices significantly less.

Are there cases you just shouldn't use a AA in a C/D spacer?

Thanks again
Brian

 

[45/70]

Just a tidbit of information. I wasn't one of the first here on the Forums to use eneloops. I was positively interested, but had a good stock of Dynacharge 1800's and Sanyo 2500's among others, when eneloops were first introduced.

When I did purchase my first set of 20 eneloop cells, they had been tested by many here on the forum for a year or so. I first discharged the cells at 100mA, then did a standard "Break In" on a Maha C9000. Part of the reason I opted for the 100mA discharge first, as opposed to a "standard" 400mA, was that the cells were 1-2 years older than those that had first been tested here on the Forum before. At that time, most all eneloops had date codes in the fall 2006 range, mine were August 2006.

Figuring the slower initial discharge would help, because the cells had been unused for a longer period than most I had been reading about, my break in results using this method achieved ~50-100 mAh higher capacity than others had obtained, on the first break in. I don't know that this really means a whole lot, but I would say if eneloops have been in storage for a long period of time, or are older when you receive them, it certainly doesn't hurt to do a minimal discharge (~100mA) first, before running a break in cycle.

I might also add that I only ran one break in cycle to achieve these results, and never felt it necessary to perform any more. It would appear that possibly, an initial 100mA (as opposed to 400mA) discharge speeds up the break in process, as others were running 2-3 break in cycles to achieve the same capacity. This is just my observation, not necessarily a proven concept.

Dave

 

[vali]

At least, according with your results, you are pretty sure your eneloops are not counterfeit ones.

 

[fishinfool]

Aloha! Another eneloop/battery newb here. When getting brand new eneloops, do you use them first before recharging since they are pre-charged? Or do you discharge then recharge them out of the box/package? Does it really matter? I also just bought more powerex 2700's and have a Maha MH-C9000. Thanks guys!

 

[brianp6621]

Aloha! Another eneloop/battery newb here. When getting brand new eneloops, do you use them first before recharging since they are pre-charged? Or do you discharge then recharge them out of the box/package? Does it really matter? I also just bought more powerex 2700's and have a Maha MH-C9000. Thanks guys!

Based on everything I read and then decided to do you can

1) Use them straight out of the package and never worry about it or do a break-in later

2) Be ultra nerdy by doing a break-in on the C9000 immediately to try and maximize the capacity.

And to do #2, the best(most conservative) overall recommendation I found was to do the slowest possible discharge on the C9000 (100ma, takes forever) and then a full break-in cycle. However this takes almost 3 days total for each set of 4 batteries. I have completed 12 out of 38 new Eneloops I now have and I've had mine for almost 2 weeks.

 

[fishinfool]

Based on everything I read and then decided to do you can

1) Use them straight out of the package and never worry about it or do a break-in later

2) Be ultra nerdy by doing a break-in on the C9000 immediately to try and maximize the capacity.

And to do #2, the best(most conservative) overall recommendation I found was to do the slowest possible discharge on the C9000 (100ma, takes forever) and then a full break-in cycle. However this takes almost 3 days total for each set of 4 batteries. I have completed 12 out of 38 new Eneloops I now have and I've had mine for almost 2 weeks.

Wow, 3 days to do 4 batteries is a long time but if it helps make them last longer, then I'm in.

Quick question, after the batteries are charged, is the mah that shows up on the c9000 the total charge for that battery? I have these older 1800 nimh that, when charged, only shows around 1300+ mah. Does that mean 1300+ is the most it can be charged?

Thanks!

 

[AnAppleSnail]

Thanks,

Are there cases you just shouldn't use a AA in a C/D spacer?

Thanks again
Brian

Avoid it for uses that would exceed the rated current for the AAs.

 

[brianp6621]

Wow, 3 days to do 4 batteries is a long time but if it helps make them last longer, then I'm in.

Quick question, after the batteries are charged, is the mah that shows up on the c9000 the total charge for that battery? I have these older 1800 nimh that, when charged, only shows around 1300+ mah. Does that mean 1300+ is the most it can be charged?

Thanks!

You only have to do the full process when the batts are new or if you are trying to recover dead cells. Otherwise just charge them and every 10 or so cycles (so I've read) do a refresh/analyze them.

I haven't actually just straight charged a battery yet (only used discharge and break-in so far) but I think the value at the end of a normal charge would be the amount of charge added to the cell to get it to reach full capacity. This number would be very different depending on what state the cell you are charging is in and the charge method. For instance during the break-in on eneloops, after the first charge/discharge cycle, I routinely get a final charging value of somewhere north of 2800 mAh even though the true battery capacity is only 1950-2050 mAh(the manual states in the break-in it puts 1.6C charge into the cell during break-in). The only way to tell the cells full discharge capacity is run the refresh/analyze or break-in mode. Then at the end of the refresh/analyze or break-in, the value displayed is the discharge capacity which represents the max capacity of the battery.

 

[fishinfool]

:thanks: Brian!