Best way to maintenence Eneloops?

[travelinman]

Taketheactive....I guess I'm not understanding what you mean by "missed termination". How could the BC900/700 not terminate when the LED indicator showed "full" or indicate the number of ma when using the "test" function?

I've been charging NiMH cells for over 2 years now on the BC charger and all indications including the anecdotal reports of longer run times, more transmission time (which is the real test as transmitting on a 5 watt handheld is heavy draw ~2A) on the same cells that are now 2 years old.

I'll do the tests you describe as soon as my roof is on, however my setup may alter the results.

I have a large finned aluminum heatsink (4" wide, X 1.5" deep X 7 or 8" long) that the charger rests on, with a 12v comp. power supply fan running at 1/2 speed on 6 or 7 volts blowing both above and below the charger. I also have an aluminum sheet bent to form an air deflector so that all the air goes directly toward the charger. There is NO overheating of any kind. As a matter of fact the cells are still cool to touch even when I have, on rare occasion charged at .5C.

 

[Black Rose]

Taketheactive....I guess I'm not understanding what you mean by "missed termination". How could the BC900/700 not terminate when the LED indicator showed "full" or indicate the number of ma when using the "test" function?

The charger relies on the battery to tell it when it is full and is normally detected via -dV (minus delta V).

When charging at a low rate such as 200 mA, the battery is less likely to generate the -dV that tells the charger to stop charging.
In that case, the charger continues to put more energy into the cell until it is manually removed.

That is what is referred to as a missed termination.

 

[TakeTheActive]

Re: SLOW Charge Rate Is Not Always BEST Charge Rate!

Taketheactive....I guess I'm not understanding what you mean by "missed termination". How could the BC900/700 not terminate when the LED indicator showed "full" or indicate the number of ma when using the "test" function?

I imagine many folks don't completely understand how their chargers operate. Per the specs (from both La Crosse and the CPF members) that I gathered in: TTA's NiMH/NiCD Battery Charger Specifications Thread: La Crosse BC-900

the BC-900 has FOUR 'Shutoff Mechanisms' (aka Termination Methods):

1. -DeltaV
2. Max Voltage
3. Max Temp
4. Max Time

If it misses one, there are three more 'Backups'.

Reviewing this example:

Sears DieHard 1300mAh AA NiMH    |   #1    #2    #3    #4
---------------------------------+---------------------------
06/16/09 BC900 Discharge:  350   |+1204 +1289 +1234 +1180 mAh
06/15/09 BC900 Test:  200/ 100   | 1100  1061  1165  1120 mAh
06/15/09 BC900 Discharge:  350   |+1212 +1153 +1260 +1156 mAh
06/14/09 BC900 Discharge:  250   |+1243 +1176 +1264 +1172 mAh
06/14/09 BC900 Discharge:  100   |+1722 +1384 +2130 +3380 mAh

note the OVERCHARGE of cells #3 and 4 during the 06/14 200/100mA DISCHARGE cycle. If I had done a 200/100mA REFRESH or TEST, I would have only seen results similar to the 06/15 200/100mA TEST cycle and been unaware of the damage being done. With 3380mA put back into a 1300mAh cell with an ACTUAL Discharge Capacity of 1120mAh, it appears that 'Shutdown Mechanism' #4 was the ONLY termination that worked. Make more sense now?

With the La Crosse chargers, it's important to understand WHICH capacity the charger is displaying.

...I have a large finned aluminum heatsink (4" wide, X 1.5" deep X 7 or 8" long) that the charger rests on, with a 12v comp. power supply fan running at 1/2 speed on 6 or 7 volts blowing both above and below the charger. I also have an aluminum sheet bent to form an air deflector so that all the air goes directly toward the charger. There is NO overheating of any kind. As a matter of fact the cells are still cool to touch even when I have, on rare occasion charged at .5C.

This was discussed in the CPF Archives. Your setup is actually DEFEATING 'Shutdown Mechanism' #3 and possibly affecting #1 and #2 by cooling the expected normal heating of the cells as they approach full charge.

...I'll do the tests you describe as soon as my roof is on, however my setup may alter the results.

Conducting the experiment on 'older', non-LSD cells WITHOUT the heatsink and fan stands a better chance of demonstrating the problem.

...I've been charging NiMH cells for over 2 years now on the BC charger and all indications including the anecdotal reports of longer run times, more transmission time (which is the real test as transmitting on a 5 watt handheld is heavy draw ~2A) on the same cells that are now 2 years old.

If you've done the research and feel that your method is providing you with the maximum performance from your cells, stick with it. The bottom line, though, is that the maintenance of rechargeable batteries shouldn't be governed by a set of fixed rules but more by an understanding of the principles and then choosing what works best for your unique conditions.

IMO, the further the user's requirements are from 'Daily Recharge after High Current Discharge', the less impact the variations in charging methods will have and the more impact time (i.e. cell aging) will have.

 

[travelinman]

Tnx for the very informative reply. It's nice to have people like you willing to put a considerable amount of time into passing along info that everyone should have when considering "the care and feeding" of these LSD cells.

As they are fairly new technology, I'm keeping a close eye on which ones fail, and hopefully will now have a better understanding of why.

btw...I'm from the old school and keep my regular NiMH backups in the freezer.

 

[kay188]

So you guys are saying, It's bad to do refresh cycles on the eneloops, then put them into the fridge and leave them there?

 

[bob_ninja]

So you guys are saying, It's bad to do refresh cycles on the eneloops, then put them into the fridge and leave them there?

Fridge is not applicable. LSDs are designed to hold charge for a long time at normal temps. Therefore there is no need for fridge, etc. You simply store them any place at normal temps, any place not exposed to direct sun light would be fine.

 

[thedeske]

On my first break in with a new c9000 from TDis (0G0C01). 4 new AA Eneloops - I put in each battery and selected Break In and 2000MAH for capacity. About 15 seconds apart.

A little over an hour ago, the rest cycle started.
Slot 1 shows 2851 MAH / 1.44 V
2&3 are 2850/1.44&1.45
4 is 2851/1.44

The cells were barely warm about an hour before the rest cycle. Anything out of the ordinary here?

I didn't think about starting with a discharge last night, but I can on the next set if it's worth the trouble.

 

[Black Rose]

Those figures are the amount of energy put into the cells (1.6x the entered cell capacity).

The numbers reported at the end of the discharge portion of the break-in cycle are the ones you are really interested in.

 

[thedeske]

Those figures are the amount of energy put into the cells (1.6x the entered cell capacity).

The numbers reported at the end of the discharge portion of the break-in cycle are the ones you are really interested in.

Ah - I'll get it eventually

 

[thedeske]

The numbers reported at the end of the discharge portion of the break-in cycle are the ones you are really interested in.

OK, I see. MAX figures.
2058
2049
2038
2034

Now I have an idea on time for these cells. Start of the last charge was 23hrs 40min or so.
If the last charge is actually 16 and I let it top for 2 hours, It's around 42 hours.

 

[kay188]

Fridge is not applicable. LSDs are designed to hold charge for a long time at normal temps. Therefore there is no need for fridge, etc. You simply store them any place at normal temps, any place not exposed to direct sun light would be fine.

I know fridge is not applicable, however, since it is a NiMH battery, storing it in the fridge helps lower it's discharge rate by 5% or something.

Most people cant be bothered to do so as the rate that the fridge helps it is too low.

 

[clintb]

I know fridge is not applicable, however, since it is a NiMH battery, storing it in the fridge helps lower it's discharge rate by 5% or something.

Most people cant be bothered to do so as the rate that the fridge helps it is too low.

Somewhere, out in Internet land, is a R/C electric flier who did tests on the Eneloops when they first came to market. His review prompted some a response, and clarification of certain points, from Sanyo Europe. One of those was the slowdown of self-discharge by lowering the storage temperature. Basically, yes, the fridge is good for Eneloops, but it depends on how long you're going to store them and what the ambient temp would have been had you not stuck 'em in the fridge.

 

[vali]

Somewhere, out in Internet land, is a R/C electric flier who did tests on the Eneloops when they first came to market. His review prompted some a response, and clarification of certain points, from Sanyo Europe. One of those was the slowdown of self-discharge by lowering the storage temperature. Basically, yes, the fridge is good for Eneloops, but it depends on how long you're going to store them and what the ambient temp would have been had you not stuck 'em in the fridge.

I think you are talking about this -> http://www.stefanv.com/electronics/sanyo_eneloop.html

 

[rlb4]

So what would be the best way to charge and maintain Eneloops with the LaCrosse BC-9009? They are usually charged every several months.

 

[nickanto]

Will my eneloops be ok in this charger for now?
http://data.energizer.com/PDFs/CHDC.pdf

I plan on ordering the eneloop charger when I get some more batteries, but will that do for now?

 

[lebox97]

here is one for you guy's -
I have about 25 pcs AA Eneloop cells (a few too many apparently) - that were not getting used/cycled very often over the last year or two.

So after reading these posts - I put them all through a refresh/analyze and also a break-in on my MH-C9000 - and those that were not showing good capacity (below 1900) I ran a few more times through a refresh/analyze several times more, and if needed also a break-in or two...
all of these cells ended up at approx 1950-2000mah range

EXCEPT for two cells!
these two cells got better after 1-2 R/A then got worse each time thereafter - and are now down to low 1700maH
(These two have probably been R/A 8-10 times and B-I about 4 times)

Any ideas?
run several more R/A, or B-I, or cycles, or save them for backup use?



NOTE: have about a dozen AAA's that refreshed to expected levels.

 

[Anzycpethian]

I'm storing all my batteries in the fridge when not in use (Eneloops, Tenergy D Premiums for my TK70 and 18650s - all of them around 50% charged). Is there anything wrong with that habit?
(I'm trying to cycle them regularly.)

I researched with Google and here in CPF posts but can't find a definite answer. PLEASE PLEASE HELP.

 

[SilverFox]

Hello Anzycpethian,

50% charged is good for Li-Ion, and OK for NiMh cells. NiMh cells actually do a little better when they are discharged to 0.9 volts at a 1C discharge rate. Then you do a charge/discharge cycle frequently. If you want to keep them in top condition you run the cycle once a month. They will also do quite nicely if you stretch that out to once every three months.

Eneloop and other low self discharge cells are a little different. Most people charge them up and have them ready to go. Extended storage in a charged condition doesn't seem to effect their performance very much. Storing at 50% charge in cool temperatures may give you a little better results, but I don't think anyone has tested those conditions.

Tom

 

[Samy]

I run them down in the device (flashlight,radio etc) as low as they can go, then charge them up fully and put them in storage rotation in a drawer. They seem to like being run right down then to receive a full charge. Half discharges or charges they dont seem to hold charge as long. In rotation they get used and charged about once or twice a month.

Cheers

 

[tandem]

I find having teenagers who use X-Box remotes are very useful for cycling cells. The remotes drain the cells fairly completely.

Unfortunately the expense of feeding the teenagers negates any cost savings to be had from going to Eneloop rechargeables.