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Old 02-10-2010, 02:17 PM   #2 (permalink)
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Originally Posted by micwich View Post
hi erveryone im interested in building a electric bike but i would want a range of atleast 50miles minimum.
and 60mph top speed
heres my shopping list so far
perm motor kit from Welcome To Electric Motorsport
this is what comes in the kit.

perm pmg132 motor.
alltrax axe 7245 controller.
White Roggers (600 amp peak) contactor.
Bussman Fuse block and fuse.
10' 6GA Welding cable.
Tinned copper Terminal Lugs.
Shrink tube.

now im going to run the motor at 72 volts and im hopeing to get a lipoe4 battery pack but what amp rating should i get?is 72v 20ah sufficient enough for the motor?
ive also looked into buying a PGS 120 Permanent magnet Synchronous Generator to help power the motor and to increase the range.
Has any one built a emotorbike with a Generator?
if so what sort of problems have you encountered?
any help would be much appreciated.
72V at 20Ah is about 1.4kWh of storage. Their electric bike achieves 35/60 miles using 3.3kWh of storage. (And likely it's 60 miles at 40 mph and 35 miles at 60 mph.)

Aerodynamics is your enemy on a two-wheeler, so start with a fairly aerodynamic bike. Then pack as much battery on as you can. To get 60 miles at 60 mph, you'll want to at least go with the 3.3kWh they're using (say, 50Ah at 72V, which is about 3.6kWh). Then give yourself a little margin. If your commute is 58 miles right now, 60 miles might cut it on a good day with no wind, but a low tire, headwind, detour or even just the battery pack getting tired will kill your mileage. Plus, your pack won't last if you drain it fully every day.

23 of the Thundersky LiFePo4 60Ah cells have a nominal voltage of 73.6 volts, a capacity of about 4.4kWh at that voltage, and weigh about 127 pounds plus BMS, charger and wiring. That would probably do what you're asking and a bit more.

Oh, and unless you're got a 20 mile downhill in your commute, don't bother with the generator. You probably wouldn't regen enough to even make up for the extra weight of the generator. Just time your lights and stops to take advantage of as much momentum as possible. (If you really want regen, look for a motor/controller that offer it natively.)

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