Help and advice for an eager beginner

[Marco1983!]

I recently found myself in need of a charger for my ebike. I was blown away at the price of £140. It got me thinking why cant I make 1 or at least convert an old charger. The battery in question is a 500w Bosch battery. I have an old Bosch charger I no longer need, so I opened it up and had a look. Confused I bought what I believed to be a board that I need and have found it Only converts the a.c. to dc but doesn't charge the battery. So can anyone tell me if I can build a charger out of the to pieces

 

[gophert]

Two phrases together in the same post are like yelling, "Grab the Class D fire extinguisher!"* - "Lithium Batteries" and "Beginner".

For the record, a 150£ Charger is hella cheaper than a fire.

Most multi-cell batteries have charge balancing circuitry. The name brand chargers need the feedback to balance the voltage levels of each cell. If the voltages are not making dense to the charger, it will not turn on.