I thought I'd give my old e-bike an upgrade, and I've build a 8S4P battery with charge controller (BMS). The thing is the electronics of the ebike quite working @ 31.5 V - a fully charged 8S battery is at 33.6V.
At first I thought I could throw away the idea, but when I found out it works as long as the battery stays below 31.5V I thought let's take an old laptop adapter (19V) and a 200W step-up convertor and make custom charger.
It didn't work out well. It works a couple of times, but then the laptop adapter breaks. Also the step-up convertor makes weird noises while charging.
I read somewhere here even with BMS you can't use a laptop adapter because they aren't CC-CV.. So I need some suggestions on how to make a charger that stops charging @ 31.5V.
What if I buy a step-up convertor with adjustable voltage and adjustable current, would that solve the problem?
Or what if I buy a 10S 42V lithium charger and use a step-down to get down to the desired voltage?