I see a lot on ebay advertising 30MPH out of a 36v 13a battery.
How is this possible with a rear hub, is the torque really poor as out of my 48v i only get 17-19mph
Are they over-volting or is there some other witchcraft associated.
I would like to understand how they appear so much quicker
If it really does 30mph, then as danielrlee points out, it would have to utilise a fast winding motor and a fairly beefy controller. As it's only a 36v system, then possibly a 25+ amp controller.
Anything less and it's unlikely to reach that kind of top speed.
Trouble with fast winding motors, they like amps and lots of them, and you would find that it would be maxing the controller much more often than a slower winding motor.
This of course would put a huge strain the battery and the controller would also get hotter and have trouble dissipating heat. This would probably shorten both their lives.
When I put together a MAC motor project a few years ago, I spent considerable time learning the facts of how motors, controllers and batteries work in relation to each other, before I plumped for the system that met my needs.
Takes a look through EM3EV's website to glean some info on good combinations:
http://em3ev.com/store/index.php?route=product/product&path=36&product_id=55
It's not presented in layman's terms, but you should be able to pick up the gist of how the different components work with each other. to achieve what you want out of the bike.
, however it can go 24mph on the flat. Ebay as believe what you read with a large pinch of salt.
