Hi,
I've looked at a bunch of posts and have seen conflicting info. Is this possible? Most off the shelf bike battery systems are closed so difficult to isolate 12V subsets.
Thanks,
John

 

Welcome to AAC!

You'd need a boost converter (step up voltage regulator). If you can't access the individual 12V batteries for periodic normalization, battery life will be limited by the weakest.

 

Thanks Dennis. Will look at that.

I'm not even sure they are 12 volt batteries. Think they may be banks of small lithium batteries around a volt or so. They've got odd form factors (cylindrical and sometimes triangular) that make me think this, plus I've seen some articles about people building their own to get more amp hours.
Regards,
John

 

Whatever battery chemistry they are, make sure you follow the correct charging algorithm.

You can't connect mismatched batteries in series or parallel and expect good results.

 

Welcome to AAC!

You'd need a boost converter (step up voltage regulator). If you can't access the individual 12V batteries for periodic normalization, battery life will be limited by the weakest.

Keep in kind if you increase voltage with the boost inverter you decrease current. You need enough current to charge the battery. That is going to need to be one hefty single 12V panel.

You might be better off putting 4-5 panels in series. You also want a charge controller or you could over charge your battery.

 

Thanks Dennis. Will look at that.

I'm not even sure they are 12 volt batteries. Think they may be banks of small lithium batteries around a volt or so. They've got odd form factors (cylindrical and sometimes triangular) that make me think this, plus I've seen some articles about people building their own to get more amp hours.
Regards,
John

YOU DO NOT want to mess with charging lithium batteries unless you know exactly what you are doing. Best case you burn something down, worst case you kill someone. Not even worth taking the risk. Buy an approved charger and charge form your house current.

 

Thx everybody.

I'm looking at a foldable 120 watt solar system with controller to use on an extended ebike trip, one where I may not have access to house current. This system is advertised to be compatible with lithium batteries. The bike battery system is 36 volt, 10.5 ah. The solar system is 12V. I could buy 3 of the solar systems (3 x $299/system) but that seemed like overkill, but I don't understand the math which is why I'm asking. 120w and 12v gives 1 amp. 10 amp hrs means I need 1 system for 10 hours full sun, but that's if the battery was 12V. It's not, and I'd like to get a charge time that's 1/2 of that.
Thx.