Ok so I live in San Francisco where the hills are stupidly steep. I have a little Schwinn "Hinge" folding 20in bike that I want to convert to an e-bike. I just dont know that much about the power requirements and what they actually mean in real world riding. I have gotten my selection down to two different kits (which do not include batteries) and I need help selecting one.

My priorities are:
- Torque (I need to be able to get up these hills without drenching my work clothes in sweat).
- Low weight
- Price

Not a priority:
- Speed (anywhere from 12-20mph is perfectly fine)
- Range (10 -15 miles is sufficient for my commute, especially considering I can charge it while I am at work).

That being said which kit should I purchase, a 500w 48v kit or a 500w 36v kit? The kits are the same price but the batteries are less for 36v and they weigh less... Also how large of a battery should I get for the range I am looking for? I am thinking 10ah?

Thanks in advance!