anyone any good with electronics??!

super_dad

I have an ebike battery which is 1000w and 48V.

Anyway, a couple of weeks ago I asked my dopey younger brother to charge my bike for a couple of hours... he left it on over night.

Long story short. The battery overcharged and melted the resistors on the circuit board.

I now have a new circuit board and it's all soldered up to the battery (not "live" yet as it'll just melt it again as the battery still has the charge)

Sooooo... anyone know how i'd remove charge from a battery... what appliance can I hook up to the battery in order to drain the battery and bring it back down to a normal level?...

In my (little) mind.. if I hook the black and red wires up to an appliance and just leave it running (i.e. a heater or something) then this'll drain the battery... am I right??!

any help would be appreciated.

fwor

You shouldn't need to drain the battery - you can't make a battery hold more charge than it's designed to hold!

If you want to drain it, you could for example hook it up to a light bulb, but it really shouldn't be necessary.

If the battery overheated during the time it was on charge, it may have incurred permanent damage which will limit its capacity in future, but there's nothing to be done about that now.

super_dad

fwor wrote: »

You shouldn't need to drain the battery - you can't make a battery hold more charge than it's designed to hold!

If you want to drain it, just put it on the bike and use it.

If the battery overheated during the time it was on charge, it may have incurred permanent damage which will limit its capacity in future, but there's nothing to be done about that now.

yeah, the problem is that when I hook up the ebike kit to the battery it has to go via the circuit board... if i plug in the circuit board it'll just start to smoke/melt (on 3rd board!!)...

so i need to take ouut some of the battery power... that's the advice I have been given on a battery overcharge. you would disagree??

Onyourcase

You'd probably be better to ask here:
http://www.pedelecs.co.uk/forum/electric-bicycles/9314-overcharging-overdischarging-li-ion-battery.html

Hammyman

What the hell kind of crap thing is that where it melts a charger because you leave it on overnight? If I were you, I'd ask them !!!!!! they can't design a charger to save their lives. I do not know of one single charger on anything I have ever used since I was a kid that has had anything happen to it because I've left it on connected to a charged battery.

fwor

Hammyman wrote: »

I do not know of one single charger on anything I have ever used since I was a kid that has had anything happen to it because I've left it on connected to a charged battery.

Yeah, I was thinking the same - they must have worked hard to design something that bad. The only time I've had something similar was with a NiCad battery pack charger with a pack near the end of its life - it was passing too much current due to crystalline build-up and blew the charger.

If you need to discharge it I'd use a low-wattage mains filament bulb across the battery itself, as they have good current regulation to them (because the filament increases in resistance as it heats up).

I modified my original reply just after you quoted it above because it became obvious to me that you could not put it on the bike while it is still in bits!