Uhhh, no. If you half the voltage you double the amperage. Volts x watts = amps...that kinda thing. Ohm's law ring a bell? Or is it volts x amps = watts? Or.......I don't think they make 12V motors for bikes, because the amp draw would be enormous. Thicker wire, voltage drop ect.
He wasn't being thorough in explaining himself, but it was clear to me. If you run a traction motor at 12V instead of 24, 36, 48 or however many volts, you'll need a lot more amps to make the same power. Since resistive power loss is a function of current squared, that implies much larger, heavier, and more expensive wire to make the harness and interconnects-- when you double the amp load you'll need four times the wire cross-section to have the same resistive losses in the wire. If you don't use the heavy wire, you have to accept significant voltage drops across the harness (with associated heating) when under load.Uhhh, no. If you half the voltage you double the amperage. Volts x watts = amps...that kinda thing. Ohm's law ring a bell? Or is it volts x amps = watts?
And just what is the reason? Anyone? Anyone?He wasn't being thorough in explaining himself, but it was clear to me. If you run a traction motor at 12V instead of 24, 36, 48 or however many volts, you'll need a lot more amps to make the same power. Since resistive power loss is a function of current squared, that implies much larger, heavier, and more expensive wire to make the harness and interconnects-- when you double the amp load you'll need four times the wire cross-section to have the same resistive losses in the wire. If you don't use the heavy wire, you have to accept significant voltage drops across the harness (with associated heating) when under load.
Likewise, low voltage implies a heavier and more expensive motor and controller for any given amount of output power, because the conductive path must be so much larger.
As for the OP's question-- there is a reason that no electric vehicles larger than kids' riding toys use only 12VDC.
Chalo
As a matter of fact the above setup was my introduction to electric, even motorized bikes, a buddy had one kickin' that he wasn't using so I mounted it & a small 33cc[?] rack friction drive to an ol' beach cruiser and used it as a commuter for about a season. Somewhat lackluster - it was a good, slow but steady performer... this was prolly... like 6-8 years ago or so?EV buyer's Guide said:Verdict: "Simple, crude and effective friction drive system"
The basis of the design is a simple, quiet, reliable motor driving straight onto the tyre. Powered by a similarly cheap, reliable lead/acid battery, the Zap (either a complete bike or easily-fitted kit) is a surprisingly good performer, outpacing all other friction drives. There are one or two disadvantages - the friction roller tends to slip in the wet unless you choose the tyre with care, and the roller wears out fairly quickly, although later models are ceramic rather than steel. Otherwise, a great little performer for the price. Out of production for a while, the Zap reappeared, but has now finally bitten the dust, overwhelmed by much cleverer technology from China.
We have tested the Zap kit and Zap/Brompton adaption.
UK Electric Bike Buyer?s Guide - Reviews of the best electric bikes in the UK.