How to revive weak Nimh battery packs ?
 

My TLT based crawler was powered by two 4-cell battery packs connected in series. They were made by Hobbico 2/3A Nimh 1600 mAh cells.
After only 18 months an less than 50 discharges they are no more usable. If I discharge @ 1C (less than 1.6 A) they give almost all the nominal capacity but they are no more capable of giving the high current the motor needs.
I have already tried to cycle them 3 or 4 times with low current and I regained a bit of lost nominal capacity, but I had no improvement on the high currents.
Is there something I can try before buying a new good Lipo and live happy with it ?

Thanks
Filippo

Re: How to revive weak Nimh battery packs ?
 

What battery connectors are you using? If they are Tamiya's, they may have finally died. Switch to Deans or something similar.

What happens when you try to pull high power? Does the rig die, or is it something else?

What radio?
What ESC?
What motor?

I should hope you're not talking about THESE or THESE, as they are receiver packs, and the tiny 20 gauge wire will not handle much current. If those are what you're using, chances are excellent you've burned up the wires and/or the connectors. Those were the only Hobbico packs I found after a quick search over at Tower Hobbies. If you're using something different, could you please provide a link?

(and perhaps a link to what LiPo you're considering getting?)

Re: How to revive weak Nimh battery packs ?
 

Sorry to hear that your packs are dying. That unfortunately is normal with those 2/3A cell packs. I went through a lot of them when I was racing my 1/18 scale Xray.

It is in the nature of those batteries and they don't live very long with the type of abuse we give them.

On the plus side is that they are relatively cheap to replace. I would look at Cheapbatterypacks for replacements and they can wire it up for you.

BTW I have about a dozen dead packs to dispose of.

Re: How to revive weak Nimh battery packs ?
 

I switched to Deans some years ago and now I always replace any connector with them :D
I did't write anything about radio and esc because the problem is in the battery pack. I have some Lipo 3s packs for my scaler and my TLT crawler performs well with them.

My battery packs are those of the second link with a new deans connector applied to them. I state again that in the past they delivered the power needed and the 20 gauge wire has never been a bottle neck, then suddenly they don't give high currents any more. Don't know if it can be related to a burned wire but if you believe I have a chance to revive the batteries replacing the wires I will try.

I have many Hobbico 2/3A battery packs and my experience says that those damn packs wear very fast with aging. It seems to me they have like an expiry date of about one year, also with a relatively small number of discharges !

Perhaps it is time to switch to Lipo definitely. I should look for a 3s with a minimum capacity of 1500mAh and 25C discharge.

I would appreciate very much any advice.
Thanks
Filippo

Re: How to revive weak Nimh battery packs ?
 

Deans are decent, so that's OK.
I've never been a fan of 2/3A cells, I always use sub-C's. But, if they've worked fine for you in the past, that's OK.

Since you are also using LiPO's, we will assume you have a decent LiPO charger that can also balance them. I think you should just just to all LiPO.

If you comp, then something in the 800 to 1300mah 3S with at least a 35C rating will do you well. The 800 should do one comp course and a little more. The 1300 will do 2 comp courses.
Big packs (high mah) can get away with a lower "C" due to the mah. The smaller the mah, the more you need to do better in the "C".

My son & I run 325mah (?) 2S 65C in our MRC's. We use 1350mah 3S 35C in our 2.2 comp rigs.
The 325mah packs are made by ThunderPower, all our other batteries are by Elite. We buy all from CheapBatteryPacks, but that may not be an option due to your location.