Reviving batteries

[Mash Potato]

I’ve got GP 3700 cells, some are new, and some are a few years old.

I’m running an 11x2 checkpoint motor in a B44 with a 19T pinion on an indoor track just for info.

I’m having a few problems with some of the older packs dumping before the end of the race. The new batteries are fine, and so are some of the older ones. But a couple of the older ones seem to dump. They are all discharged to 1.0V per cell before being charged again.

Now although these “suspect” batteries are several years old, they have literally only been charged a handful of times in their life’s, probably less than 20 times. But they did sit for some time un-used.

So my questions are:
1) Have I mistreated these cells by leaving them standing (obviously this was not a good thing) and thus permanently damaged them?
2) Is there a way to re-vive them, and if so how long is it likely to last before they either die, or return to this state?

[markwilliamson2001]

Depends on how long they were stored.... It also depends on whether they were flattened/discharged fully before being stored, as you should always leave a little charge in them if being stored. My only suggestion could be to use a 'flatline' (passive discharge tray), as this got one of my older packs working again.

Mark

[Mash Potato]

Originally Posted by markwilliamson2001

Depends on how long they were stored.... It also depends on whether they were flattened/discharged fully before being stored, as you should always leave a little charge in them if being stored. My only suggestion could be to use a 'flatline' (passive discharge tray), as this got one of my older packs working again.

Mark

Thanks for the reply Mark.

They were stored for somewhere between 12-18 months to be honest. They should have had some charge in them when they were stored.

I use the LRP CONCEPT 2 BATTERY CONDITIONER set to 1.0V per cell. Should I try to discharge lower than this, would this potentially help? Sorry for the stupid questions, but I'm still pretty new to this.

[sosidge]

Your routine sounds right. Equalise then charge.

Probably what you are getting is all the life they have to give. Sometimes after a few cycles they pick up, but the cells don't like to stand for long periods.

[Col]

Assuming the cells are GP's, they will improve with use. I have a couple of sets that were stored for 6 months and were garbage at first, but have since got better (though not as good as the packs that were used more often...)

[gndprx]

I've revived quite a few packs over time and this may or may not help you out.

I dump the pack completely on a Zero 30 discharge tray. Then I'll put it on an equalizer tray that has no cutoff point (does have reverse protection though) and let it sit for about 24 hours to flatline.

Charge it at 1A until it hits temperature (120F degrees +/-). Some charger will false peak for a bit until the pack gets going.

Repeat the discharge/tray process above and then cycle twice at regular charge rates (5A or so) and it should start to come back to life.

If this doesn't work, you may have at least one cell that won't revive. Check each cells voltage at charge to make sure they are all taking a charge. Worst case scenario you can just use it as a practice pack.

Good luck