Rapid battery performance decrease
 

I have recently seen a big drop in battery life in two of my batteries. During the winter I cycled them every couple of weeks. Two weeks ago they both performed great. But today I got them out and toped them off and ran them. they both only ran about 2-3 mins max. So I let them cool and charged them again, and ran them again and still only got a few mins runtime. I tried this a few more times with same results. The batteries are EnerG 4600 and EP 4600. What would cause them both to drop in performance so fast?

I know I should just go lipo and I am in the process I just bought a lipo charger and I am saving for some lipos, but I still want to save these packs.

Thanks for any help.

Are these in a stic pac or are the side by side. Need to see what the individual cell voltages are doing which will be tough if these are stick pacs. Read this and you'll see why need to know what cell voltage is doing - look at their maintenance paragraph - #3. You may have a few very low cells -

http://www.promatchracing.com/ibins.php


Is any one or two cells getting hotter than the others when you're charging??

Yeah they are both stick packs. I did notice that they each had a cell that was hotter than the rest this last time I charged them. I guess I need to tear them apart and check the volts. If I do have some dead cells can I mix the two packs to make a good one? Thanks for the help and the link.

The hotter cells are the prob cells - either going bad or are already there. I don't see any reason why you couldn't mix - they're both 4600mah.

Try charging th packs at a 1/10C for 12 hours before tearing them apart. Stick packs especially get way out of balance sometimes and can produce similar results. More than likely you could have bad cells, but it would sure be worth it if it worked. It has worked for me in similar situations.

anyone have any experience with these pro match lipos????

http://www.promatchracing.com/proddetail.php?prod=2506

Okay so I rebuilt them as side by side packs and tested them again. I put them on the charger until 2 of the cells got hot (around 135 degrees). I'm guessing those are the bad cells but they had the same voltage as the other cells 1.39 volts. I guess I'm going to find the best cells of the two packs and try to make atleast one good one.

Thanks for the help guys!

I've had bad cells read the same voltage as the rest of the pack after charging but after I would run the pack the bad cells would read zero volts and the rest would show some voltage (as they should). I would bet that if you ran the pack the cells that got hot would read zero voltage or at least a lot less than the rest.

Before you go mixing cells on your packs balance discharge them (which you can do now that they're side by side), and drop all the cells down to the same voltage (using a discharge tray) then charge them back up! It will only take a little extra time, and could save you from having to chuck batteries that may still be good. If they're still doing it, then ya, bad cell :(

Also, I would _not_ mix cells between manufacturers even if they are the same mAh rating, unless it was a last-ditch effort. Even cells from the same manufacturer within two different packs can be different enough to cause you headaches.