bgw_savage

I usually spend hours reading posts... well here it goes starting my first. I have looked through help and I cannot find my topic.

I have read plenty about low voltage cut-off for LiPo. I have a problem with NIMH. Lets ignore LiPo for now.

I bought a lightly used slash on EBAY with 2 NIMH batteries. The batteries were the type were you buy the cells and build a battery. The cells are of good quality... Integy Intellect 4200. Well I get my setup ready (I am getting into electric after spending forever in nitro). I purchased an Onyx 220 charger with separate adpaters to Deans. The first battery charged no problem. The second battery caused an error code on my new charger. Fearing the worst I asked a friend to borrow another NIMH. Luckily, the charger is OK and charged Team Orion and Venom batteries without a problem. Then I checked the voltage of the second battery and was 0.2 volts. I could not charge it. The EBAY seller claims they are "good" batteries.

To remedy the situation I borrowed the HotBoddies charger from the E-savage RTR package from a friend. I used this "dumb" charger to get the voltage up to 7.2 volts. I was then able to charge on the Onyx 220... my charger is apparently to smart to charge a low voltage NIMH.

SO MY MAIN QUESTION - is this previously low voltage battery "bad" and how do I keep this from happening again? Do I need to invest in another charger to deal with this in the future?

Thanks in advance.

freeair

i think you need to test each cell individually with a multimeter . as you know normal voltage is 1.2 volts per cell so if you find one cell alot lower than the others you know you have a dead cell.

Rodney

Nixx batteries always need a forming charge when new or after having sat around unused for a while. A forming charge is defined as charging at 0.1C for 16 hours (you do not have to discharge before doing this forming charge). It may take three or more cycles of this (discharging down to about 1.1 volt/cell between charges at not faster than 0.33C) to bring them up to full capacity. Of course, if any single cell fails to charge at the first attempt, it is most probably toast and can not be revived. If, after these forming charges, the battery fails to deliver at least 80% of its rated capacity, it is most likely over-the=hill and ready for replacement.

bgw_savage

Ok... thanks Rodney! Funny that is my dad's name too. I will try that.

To be clear... the 0.1C for a 4200 mAh battery is charging for 16 hours at 420 mAh. I have been charging at the 1-hour rate of 4.2A.