Batteries way too hot!

[HYDROPLANE]

I was out running my villain ex this weekend and all was fine until I ran my last set of packs. I ran the boat as I usually would, discharging the packs down before bringing it in. Once I pulled the boat from the water, I proceeded to remove the packs to let them cool. When I removed the packs, I was instantly burnt by the one cell. It was insanely hot. Six out of the seven cells were warm as usual, but the one cell was boiling hot! It was so hot that it burnt a nasty hole in the top portion of my hull, and the shrink on the cell was melted away almost completely. I am not sure if the cell vented or leaked. I know cells get hot from rapid discharge, but they should not be this hot. I was just wondering what happened here? Has anyone else ever had this happen? By the way, I am running (2) 7 cell packs. Powerizer 4200Mah Nimh. I have a few sets of these packs and some orion packs and I have never had this problem with any of them. The boat is stock other than a water cooling kit. What can I do or use to patch the hull. It is ABS plastic. Someone please enlighten me.

[Rex R]

sounds like your pack got out of balance... every so often you want to give them a loong slow charge (about .5amps) to bring all the cells up to the same state of charge. course the high capacity nimhs have a history of going bad even if you do every thing right.

[HYDROPLANE]

What exactly does out of balance mean? Exactly what happens to the cell to get it that hot? What should I do to patch up the hull?

[birdy233]

out of balance means that one cell or more cells reached a fully charged state before the others did, that means your charger will keep on charging until the other cells a charged, causing your other cells to take a beating. You can get an individual cell discarger and discharge the packs to get them all down to .05 volts before you charge. Then as stated, occasionally slow charge them to condition your packs. Your better bet is to get some lipos, those can be balanced as you charge.

As for patching the hull, pick up some sheet ABS from the hobby shop or Tower and CA a patch from the inside and outside the hull, you can get fancy and cut the hull out to make a uniform square, cut the patch to fit snug in the now squared hole (still do the inside patch to back it), CA or epoxy the patch in and sand smooth

[HYDROPLANE]

So does this mean that the cell or cells that got real hot are trash? The voltage is .03

[birdy233]

the ones that got so hot it burnt you, more than likely. may have vented on you. it will still work but not well and will affect the rest of the pack. buy a replacement cell and replace the bad one

[HYDROPLANE]

Will do. Another question about a seperate battery issue. I have a set of packs that seems to be false peaking on multiple occasions. I am using a super brain 977 charger. When I charge the packs it shuts off at 1500 or so MAH. The packs are 4200 packs. If I let them cool and charge again, they seem to take the remainder of the charge? Should this be necessary? Just wondering why they wont peak at 4200 the first charge. I discharge them first and have used variuos charge rates. I have also cycled them multiple times. Please help!

[Rex R]

well one thing you should know is; nimh cells do not require discharging before recharging. rather just replace what you've used(kinda like topping up the fuel tank in your car when you're only down a 1/4 tank)

[SweetZ28]

First off those powerizer cells are garbage get some better packs like GP's or something your boat will go much faster....also on the 977 set the MV setting to 10MV and try charging your pack...if that dont work try15MV on my good GP packs i use 10MV with my 977 and it works fine.