Had a battery pack with bad life, pack could still hold a charge, but the runtimes were seriously degraded (1hrish). Decided to re-new the cells instead of throwing away and buying an entirely new pack.
Not much information on the net about people doing this. DO NOTE THAT THE CELLS ARE LITHIUM POLYMER TYPES, PUNCTURING AND/OR DAMAGE TO THEM CAN/WILL CAUSE A FIRE. Still decided to do it though.
To expose the cells. You’ve gotta remove the top aluminium sheet that’s mounted with a very sticky tape. Start at the corners and go slow, applying some solvent (used IPA for this, seemed a good idea), there’s a thin metal cover between this and the cells, so you shouldn’t be able to start a fire unless you’re seriously using a lot of force. The button and LEDs are not part of the cover. (Button is simply a little metal thing that extends all way down into the controller/protection PCB.)
With the cover out you’ll see yet another metal plate, lift the corners and work your way around it’s mounting tabs. There might be some adhesive on the tabs, gently get those off.
With that out, next gently remove the little cover just above the power connector, doing this will free the board and cells enough to get them to move. Then with gentle persuasion, guide the cells and board out.
Next up in this series, replacing and then finally putting the pack together.