I'm probably off in calculations, but I was always fascinated by range-extender type hybrid cars. That is, pure electric drivetrain, with a small engine, perhaps 2-cylinder, that simply drives a charging system. VW is building a prototype car that so far has an estimated milage of 485 MPG. Pretty damn good considering it's a full-out car.
So my calculations are as follows:
a 50cc motor is rated at 150mpg (and some forum members here have achieved very close to that). I figure that's around 32km/h (about 20mph), or 8.88 m/s.
44T sprocket to a 10T drive sprocket means a ratio of 4.4:1 and internal gearing of 4.1:1.
26" bicycle tire measures 183cm around, or 1.83m, spinning 4.857 times per second, or ~291.5 RPM to equate to 32km/hr
using that gearing, thats 5258 RPM, mid-range for the 50cc.
Take the throttle off, and use the idle screw to maintain a constant-ish 1300 RPM. ASSUMING a carb gives the same amount of gas per-stroke (not utilizing an expansion chamber), this should mean 1/4th the fuel consumption.
Run it a little lean, it'll be run with nearly no-load (alternators are easy to spin with the hand so a motor shouldnt have a problem)
150MPG at 20mph equates to 7.5 hours of runtime on a gallon. assuming the above about fuel consumption, I get 30 hours of runtime at idle speeds before the gas runs out. we'll assume this number even if we run lean.
The motor does not drive the wheel, but rather drives a 320A 12v alternator, by my calculations, the 50cc motor should be able to drive said alternator with ease at 1300RPM, utilizing a belt-drive system replacing the small bevel gear.
convert the voltage to 24v for 160A (minus losses)
Utilize a 24v 20AH battery setup of some kind that can take rapid charging.
run a 500w 24v electric hub motor. That's just a little bit over 20A on 24v for 500w, and should be able to push us over 50km/h (my friend's 500w scooter weighs 420lbs with me on it and hits 45 with relative ease)
So all that said, we can get into the milage conversions. the batteries will drive the motor for an hour for a respectable 50km range. Kick in the engine to charge the batteries, 20A goes to power the motor while the batteries charge, 140A charges the batteries in ~8.6 minutes (ASSUMING they can take that kind of amperage). you have 30 hours of runtime, totalling 209 full-charges for a one-gallon tank.
1 charge = 1 hour of run time
8.6 minutes of charging per charge
so 8.6 mins x 209 = 30 hours + 209 hours (1 hour per charge) + initial charge = 240 hours. 10 days. 240 hours x 50 km/hr = 12,000 KM... or just shy of 7500 miles per gallon. To put that into perspective... Toronto, Ontario to Austin, TX is a mere 2600km. can you imagine going 3 round trips on $5 gas? it'd take forever, sure, but the cost would be... nothing.
EDIT: Sit and rotate, EPA
So my calculations are as follows:
a 50cc motor is rated at 150mpg (and some forum members here have achieved very close to that). I figure that's around 32km/h (about 20mph), or 8.88 m/s.
44T sprocket to a 10T drive sprocket means a ratio of 4.4:1 and internal gearing of 4.1:1.
26" bicycle tire measures 183cm around, or 1.83m, spinning 4.857 times per second, or ~291.5 RPM to equate to 32km/hr
using that gearing, thats 5258 RPM, mid-range for the 50cc.
Take the throttle off, and use the idle screw to maintain a constant-ish 1300 RPM. ASSUMING a carb gives the same amount of gas per-stroke (not utilizing an expansion chamber), this should mean 1/4th the fuel consumption.
Run it a little lean, it'll be run with nearly no-load (alternators are easy to spin with the hand so a motor shouldnt have a problem)
150MPG at 20mph equates to 7.5 hours of runtime on a gallon. assuming the above about fuel consumption, I get 30 hours of runtime at idle speeds before the gas runs out. we'll assume this number even if we run lean.
The motor does not drive the wheel, but rather drives a 320A 12v alternator, by my calculations, the 50cc motor should be able to drive said alternator with ease at 1300RPM, utilizing a belt-drive system replacing the small bevel gear.
convert the voltage to 24v for 160A (minus losses)
Utilize a 24v 20AH battery setup of some kind that can take rapid charging.
run a 500w 24v electric hub motor. That's just a little bit over 20A on 24v for 500w, and should be able to push us over 50km/h (my friend's 500w scooter weighs 420lbs with me on it and hits 45 with relative ease)
So all that said, we can get into the milage conversions. the batteries will drive the motor for an hour for a respectable 50km range. Kick in the engine to charge the batteries, 20A goes to power the motor while the batteries charge, 140A charges the batteries in ~8.6 minutes (ASSUMING they can take that kind of amperage). you have 30 hours of runtime, totalling 209 full-charges for a one-gallon tank.
1 charge = 1 hour of run time
8.6 minutes of charging per charge
so 8.6 mins x 209 = 30 hours + 209 hours (1 hour per charge) + initial charge = 240 hours. 10 days. 240 hours x 50 km/hr = 12,000 KM... or just shy of 7500 miles per gallon. To put that into perspective... Toronto, Ontario to Austin, TX is a mere 2600km. can you imagine going 3 round trips on $5 gas? it'd take forever, sure, but the cost would be... nothing.
EDIT: Sit and rotate, EPA
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