Is it best to keep a NiMH AA stored charged or discharged?

[fishwatcher]

Now that I have 2 Costco packs of Eneloops handy, I have a steady supply of charged AA's I can use @ anytime.

I have a few higher capacity NiMH's (2650 and 2300), and plan to use them either "fresh" or possibly "freshly topped off", when I know I have higher battery needs, for a given day or weekend.

Once my higher capacity NiMH's are fully discharged, should I re-charge them, and then top them off, just before I use them? Or store them discharged, and charge, the night before I plan to use them?

Thanks!

 

[Anders]

Hello

I store my cells fully charged and make a charge/discharge cycle every 30-60 days or top them of when they are 50%.



The best way is perhaps to do as Silverfox have told us:

"A cell is considered fully discharged at 1.0 volts, under a light load, or 0.9 volts, under a heaver load. Resting, open circuit, voltage should come back to around 1.15 - 1.20 volts after the load has been removed.

When you store NiMh cells, discharge them to 1.0 volts under a moderate load before storage. If you are interested in peak performance from your cells, run through a charge/discharge cycle every 30 days. If your needs are "less demanding," you can put off the charge/discharge cycle for 3 or 6 months, or until the cell voltage has dropped below 1.2 volts.

If you anticipate long storage (1 year) and not being able to access your cells, you can discharge them, then do roughly a 25% charge on them. This is roughly how they come from the factory.

Tom"

Since he know a lot more of NiMh cells than most of us you better do as he said to get the most out of your NiMh cells.


Anders

 

[VidPro]

the problem comes in when they self discharge themselves to below the desired low voltage, and completly 0 out themselves and decompose :sick2: on the shelf

so this always is a quandry, on one side i need to store them mostly discharged, then charge them to use, which will make them very happy.

on the other side the non LSD cells which your planning on storing, will self discharge themselves sit there for a long time, and possibly get ruined.

i wonder if the 40% thing would work ok, as long as they can hold that up for a while. on mine if they kept doing the self discharge to death thing, i just kept tossing them. i dont really know what to do myself cause they are working ok, but killing themselves because of thier self discharge.

use it or lose it, the motto i keep comming back to, i have to "maintanance" them and its a pain, if the enloops keep doing what they are doing for time, i think i am ready to chuck the things that require to much maintance, and replace the whole lot with enloops.

other than that , keeping them low, and charging before that job or play , is a great method.

 

[fishwatcher]

Thanks for the advice everybody.

This is very helpful.

 

[WDG]

the problem comes in when they self discharge themselves to below the desired low voltage, and completly 0 out themselves and decompose on the shelf.

I have a set I keep in discharged storage with monthly cycling. My thinking is that if they are self-discharging to 0v in 30 days, they probably aren't worth storing.

if the enloops keep doing what they are doing for time, i think i am ready to chuck the things that require to much maintance, and replace the whole lot with enloops.

Wish I'd discovered the Eneloops BEFORE I bought these other cells, instead of right AFTER. They're too new to chuck, though I rarely actually use them, now that I have the Eneloops.