Proper Discharge Rate for NiMH Battery

[Grumpy]

I just bought a B6D charger from airsoftparts.ca and the manual is a bit vague on discharging a NiMH pack. I am trying to "cycle" and/or revive an Intellect 9.6v 1500 maH mini battery. My big question that I cannot seem to find any info on is "what is the correct discharge rate"?

The charger's default setting is 0.1A/0.1V, but I see in the battery FAQ here it is mentioned not to discharge below .9v per cell. I don't know if the charger's setting is per cell or total voltage.

I am looking for some advice from those that have battery experience to point me in the right direction to properly cycle or discharge/charge with this charger.

Any help would be appreciated.

Thanks

[voorhees -FWA-]

I discharge with my B6D at 1.0A and 3.0V... Don't remember where I read to use that setting but it was somewhere :P My 9.6 1600's don't seem to mind this setting...

[Styrak]

DO NOT DISCHARGE NiMH's!

The regular charge/use cycle is good enough. Charge them whenever you want, but NEVER discharge them (except by shooting in a gun, etc).

[Grumpy]

Why not discharge a NiMH? The battery does not seem to have enough "uuuumph" anymore (i.e. it sometimes won't even turn over my AEG), I might have killed it with a defective "Blue Box Of Death" smart charger, so I am trying to deep cycle it and perhaps revive it

I have a few other batteries like this also

Originally Posted by Styrak

DO NOT DISCHARGE NiMH's!

The regular charge/use cycle is good enough. Charge them whenever you want, but NEVER discharge them (except by shooting in a gun, etc).

[Styrak]

If that's a last ditch effort, then OK try it. But not for new batteries.

You also might just have to get new ones.

[Con Murder]

Go to an R/C hobby shop. The local one helped me program my B6D for the battery types and sizes I most often use. I don't discharge mine as they are in working order, although I have read that your not going to revive a damaged battery unless you have the leads from each cell to hook up to balancer. The local hobby shop should be able to advise you of what to do. Either disassemble the pack and ensure each cell is at same voltage and capacity or reassemble the pack with the balance leads.

[Spike]

A lot of new NiMh batteries won't charge fully until they're cycled a few times, it even says on the packaging.

[Con Murder]

Spikes right. And Styrak, your right for most airsoft use but we should start taking cues from the R/C dudes to get longer battery life times.

It wont help man the discharge rate will be equal for each cell in the pack. Your problems originate from an irregularity in the cells of the pack. One or more is operating lower than the rest.

7 cells at 1.2v equal 8.4v but if you have managed to damage a cell and your configuration is 6 cells at 1.2v and 1 at .9v you can charge/discharge all you want it will always be at a constant equal amperage for each cell in a pack. That is unless you disassemble the pack or reassemble it with balance leads.

[CDN_Stalker]

I'll back up the never discharge NiMH batteries, you can destroy them if you do it too many times.

If your battery seems crapped out, it could be one or more cells has crapped out making the battery pack weak. Check the voltage of eash cell in the pack, nominal is around 1.2VDC, but if one cell reads close to 1VDC, then it should be replaced (the cell, not necessarily the entire battery).

[voorhees -FWA-]

Generally speaking, Ni-MH batteries do not suffer from the "memory effect" and don't require conditioning. I do this to ensure top performance, I discharge and recharge once for every ten charges. For Nickel Cadmium (Ni-Cd) batteries, conditioning is recommended every time you charge your batteries.
The only thing that will really hurt Ni-MH batteries is over-charging thembecause they will self-discharge if left unused. Generally, within 30 to 60 days, batteries will become completely drained. When using them, you will need to first recharge them. After extended storage, you may need to condition the batteries several times to regain nominal performance...

[mcguyver]

Very often 1 cell dies and needs to be replaced. I've done this many times, and it's is always the problem with poor-performance of packs that previously performed well.

[Grumpy]

Thanks for all the input guys, but I still have not gotten the "definitive" answer to my question of:

"what is the correct discharge rate" for my B6 charger?

I see one comment of 1.0A/3.0V but 3.0V would be way too low for a final voltage I would think. I am guessing that 9.6V x .9 = 8.4V final discharge of a 9.6V cell would be more realistic, but I am just guessing here and I would really like some of the battery experts to chime in if at all possible.