Battery charger, sparking?

[Sammich]

What output voltage and amperage charger should I use for a 36v e-bike (battery is 36v 10.4a)?

Which brings up second question: when plugging a 42v 2a charger from another 36v e-bike into it, it sparks momentarily at the connection (like shorting a capacitor). It also will illuminate the charger light green before plugging into the wall. After that it acts normal (red until charged, then green). Is this normal for some bikes, or is there something wrong.

 

[major masingil]

You'll get a spark from the difference in voltage between the battery and the charger. You can avoid it by plugging the charger into the battery before you plug the charger in the wall. A lot of times the battery has an on/off switch. Check yours. If it has a switch, turn it off before you plug anything into the battery and before you install it on the bike.

 

[Sammich]

I always plug the batt into the charger before plugging into the wall. (Vice versa for disconnect), and no switch seen on the battery itself. Good advice, though. Thanks