Need quick battery help
 

I have a set of 7 cell NiMh batteries that I'm hoping to run tomorrow in the woods. I tested the truck today to make sure everything was ok and it was for quite some time. Then the truck had VERY VERY little acceleration. I took out the batteries and checked the voltage and they were sitting near 9 volts still. They were a little warm but not to hot to hold indefinitely. Please help diag this before I leave tomorrow.

Thanks!

RE: Need quick battery help
 

My diag is that this sounds normal. You ran them dead, right?

RE: Need quick battery help
 

No, not dead at all. Both batteries were still showing over 9 volts and I only ran them for about 10 mins. Normal run time in that truck (it's my crawler) is about 45 minutes to an hour. Definitely not dead batteries.

RE: Need quick battery help
 

The runtime and voltage may be irrelevent. If the packs aren't discharged then the trouble is in the truck. We would need some details to diag the vehicle.

RE: Need quick battery help
 

I ran the batteries in my crawler Emaxx 3906, they ran fine for about 10 minutes then started acting this way. I put them in another emaxx 3906 with a single Titan 775 and they immediately did the same thing. I just now plugged them into my brushless Emaxx 3905 with telemetry and it was telling me that the batteries had very extreme voltage drop. Anything else you may need to know let me know.

RE: Need quick battery help
 

I'm back to my original guess then. The packs are discharged. If not then they at least have 1 bad/weak/out of balance cell.

RE: Need quick battery help
 

Any idea how to find out which cell is bad if they are all showing correct voltage unless a load is put on?

RE: Need quick battery help
 

Yes, probe each cell during the discharge OR feel for the hot cell. I doubt you have a bad cell in each pack.

RE: Need quick battery help
 

I'm going to try and charge them after they cool completely and see what happens afterwards. Thanks for the info here!

RE: Need quick battery help
 

I would guess that the first time they weren't charged all way explaining the short runtime. Hopefully a recharge will "fix" them. ;)

RE: Need quick battery help
 

i would just go get a lipo. that'd solve your problem

RE: Need quick battery help
 

the cells are flat, this happens after ya store them with power left in them. you might be able to cycle them a few times and get them back up, but most likely not being they're cheap cells. lipo are the only way to go, they last 1000's of cycles and are way more reliable than NiMh or NiCd.