help, intellect 7 cells
 

i bought and rearranged the 7 cell packs for my emaxx and ran them 3 or 4 times now. On my last run the truck lost its charge very very very fast. I got less then 5 mins on it and i usually get a good 20 or so. The only thing i changed that time was i charged at 2 amps instead of 3. I also noticed one of the the battery connectors negative terminals came undone. I resoldered it, and they still died quickly. Any idea what could be going on? thanks

did any single cell get hotter than the rest. you could have a bad cell

also check the the rest of the solder joints to make sure you dont have any other bad ones.

When you rearaged the cells did were you careful not to use to much heat when soldering them. Ecessive heat can cause a cell to go bad. Its best to use a high wattage soldering iron so you can apply heat quickly and not keep the heat on the cell for more that 5 seconds. More than that and you risk melting the seal in the cell and causing it to fail quickly.

I have ruined more than one cell in my day. I hate soldering packs. Its a PITA :019:

well i will try to tell after there done charging. ill let you know if one cell is hotter the the other.

ya i just ran it and they went dead in under a min, i checked both packs and found that one cell got hotter then all the others, i assume this is the bad cell?

Probably.

Do you have a volt meter? Try testing the voltage of each cell and see if there is one or more that is lower than the rest. Those will be the bad cells. Unless you bought matched sets you should be able to replace the bad ones with new cells. Just make sure that when you assemble the pack all of the cells are already charged to the same voltage. Be carefull when you solder then new cells in so you dont ruin the new ones with to much heat.

Use a decent quality high watt soldering iron. 60 watts is recomended. If your good you can do it with a 40 watt iron, but it take more skill. You should not apply heat to the solder joint at the end of the cell for more than a count of 4 then pull the heat off and let it cool back to room temp. If you didnt get it soldered correctly the first attempt just wait for it cool before tying again. You already found out what happens when you use to much heat.