Reviving NiMH batteries?

[theseeker411]

I have 2 Trinity 3000 MAH NiMH racing packs that have sat for a while. I tried using them again recently and they don't hold a charge at all. 30 seconds on my discharger and they're drained, even from a full charge. I don't want to just toss these things in the trash, so is there any way to save 'em? Thanks.

[pyro18t]

are the NiMH or NiCad? do you have a peak chrager or a timed one? are you sure it's your batteries and not your charger?

Jay

[theseeker411]

I'm using a Dynamite Prophet Plus peak charger that can handle both Ni-CD and Ni-MH batteries. It's brand new, so I doubt that's it. And yes, the batteries are Ni-MH.

[ElectricThunder]

Cycle them. Charge, then discharge, charge, discharge, etc. Do that a bunch of times and see if it helps any. Also, charging at different amperage rates may help. How long have they been sitting?

[theseeker411]

They've sat for a couple of months. I just didn't have time for r/c during school. Thanks man, I'll have to give that a shot.

[guver]

I would bet that they are simply not "full" rather than "not holding a charge" Perhaps that's what you meant anyways.

A for sure way to tell is to force charge them to capacity then check them with your discharger.

[TunaCan Charlie]

I bought two new Venom 3600 stick packs awhile ago on E-Bay. One pack charges very well and has decent performance. The other pack peaks after 5-10 minutes and runs very slow for a short period of time, then dies. Both packs were new when bought, and both were charged the same way, with the same charger at 4 amps. Funny, I have the Dynamite Prophet Plus as well. Anyway, what do you think? I've heard of false peaking and possible dead cells, but do you think the "charge, drain, repeat" will wake up this pack? :confused:

[pyro18t]

I bought two new Venom 3600 stick packs awhile ago on E-Bay. One pack charges very well and has decent performance. The other pack peaks after 5-10 minutes and runs very slow for a short period of time, then dies. Both packs were new when bought, and both were charged the same way, with the same charger at 4 amps. Funny, I have the Dynamite Prophet Plus as well. Anyway, what do you think? I've heard of false peaking and possible dead cells, but do you think the "charge, drain, repeat" will wake up this pack? :confused:

to me that sounds like dead cells because you said it's slow. I would contact venom and see of they can do anything for you, the worst they can say is no

Jay

[spidude]

try using a battery manager (e.g. Spintec or TRinity) on the batteries.

[Neon_Dave]

I'd also say cycling the batteries a few times should revive them, at least to the point where they last longer and can hold a charge better...

[highroller]

The Panasonics cells (nicad and NiMH) are the only ones prone to short life and inconsistant cycles-no matter what you do them there is noticeable decline after 6-8months then after a year cells don't perform well. Other cells can sit for up to 8months, but do not charge or discharge normally for one to three cycles.
Cycling (charge the pack, then discharge it) if charger has a display note the peak voltage, MAH rate. The MAH should always be above the rated capacity of cells, for most cells. Before charging the pack(s) use something to remove any residual voltage from cells for stick packs (a) Discharge Resistor (b) single 1157 lightbulb or discharge tray for inline packs. Leave the load on either until resistor is cool or individual cell voltage is between .25 -.05 volts (.30 to 1.50 volt for 6cell pack). Charge the pack at a low rate to gets cells to balance, then discharge using load of between 10-25amp. Allow pack to sit 24 hours and repeat increasing the charge rate to a normal level checking the peak rates at end of charge.
Another way is to just the pack up using a slightly lower charge rate and running it in vehicle (get some use out of pack) discharge pack of any remaining voltage to a .90 volt per cell level. Allow pack to rest - give cells time to balance, wait 1-2 days then charge normally and use in vehicle again to see if runtime and performance has increased. This has worked for most batteries except the Panasonics, once cells begin to decline it's time for new packs. GP3300 have about the same performance and lifespan of Nicads, should see a good 3 years + of good use even when not used for as long as 8 plus months once they get used consistantly they perform normally.
Not even the IB3800 for all it's high voltage stays as consistant as the GP3300 did.

[theseeker411]

Well, these are all Panasonic cells, dangit. Guess there's no real way to bring these back, eh?

[Taylorcraft]

411,

Just my two bits worth:
First of all, there might be ONE or a couple of cells per pack that's gone bad, messing up the whole enchilada. I'd started by measuring the voltage in each cell individually, and then trying to charge it separately if a cell reads a significantly lower voltage than the rest. This MIGHT work, but I can NOT guarrantee it. (It's worth a shot anyway, for saving money). If this works and you get that cell/those cells up to par, you should do the same with the rest of the cells - charge them individually and cycle them at least once.

If it doesn't work, I'd either replaced the broken cell(s) or replaced the whole packs with new NiMH or LiPO batteries. LiPO packs now has a rather good current drain and weighs MUCH less than even NiMH batteries.

Brg

Taylorcraft
____________________________________
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