Very old 1600mAh NiMH questions

[ltiu]

I recently got hold of some "on sale" RC 9.6v battery packs. These packs have 8x AA rechargeables in them. The package read:

"Best if recharged by Oct 2005".

We are now in March 2008. 2.5 years away from the "best by" date.

What does that mean? Are the AA batteries in the battery pack still usable? Any dangers and precautions? Anything I need to do to recondition the battery?

Thanks for any tips and suggestions.

 

[SilverFox]

Hello Ltiu,

The first thing you need to do is to measure the voltage of the pack.

Let us know what you measure and we will go from there.

Tom

 

[ltiu]

Measure before or after recharging?

 

[Mr Happy]

Measure before charging.

 

[ltiu]

Hrmmm, too late. I charged the pack a bit then gave the battery to my nephew for his RC boat He lives far away ... any danger of exploding or anything else bad happening???

 

[Mr Happy]

There's no actual danger with NiMH, it's just a question of how well they perform. I believe if the voltage on a cell is below 1.0 V after storage, then it may have suffered some internal deterioration. In that case a bit of careful rejuvenation before normal charging might be of benefit. I'm sure SilverFox can advise better.

 

[ltiu]

I don't really care about battery performance. I care more about safety. The RC boat came with a 650 mAh NiCad. I thought having a 1600 mAh NiMH would allow the boat to run 2.5 times longer. But if the battery ends up only performing 1/2 it's rating. Then that is fine as long as there is no danger of explosion or anything bad like that.

 

[SilverFox]

Herllo Ltiu,

The issues with NiMh cells exploding in battery packs was caused by repeated topping off packs that were already fully charged.

If your nephew simply charges and uses the pack, there should not be any issues. If he gets greedy and tries to get that last little bit of performance from the pack, that is where he may run into problems.

Tom

 

[ltiu]

Thanks Silverfox.

I specifically told him not to overcharge the original 650mAh that came with the RC boat. Max 4 hours as indicated in the user manual.

I told him since the old 1600mAh pack has twice (roughly) the capacity of the 650mAh, then he needs to charge it for 8 hours but no more. That should be good enough safety precaution?