@saand
you could be right.. but i always thought that box in the middle of the cable was the charger

but now with all this work you just told me about..and the fact that a 48v lithium battery costs 500-800$.. im starting to think i should just leave the bike AS IS
@myzter
4 cell 48v and 10-12 amps
could you link a Canadian site that sells those solar panels ? cuz all i got is ebay.ca and no stores apart from Addison sells solar panels in Montreal