didn’t see a response so here’s my 2c: building batteries is fun but not cheaper until you have made 10 or so and the cost for tools and mistakes levels out 
. if you just want to open that can of worms it is fun and rewarding imho. Defiantly post up your issue on The battery builders club . Seems like with a little troubleshooting you might be able to salvage some life out of your current battery - post up all your battery specs there and get that sorted first.