4 years ago

137

Build An Electric Motorcycle - DIY E-Moto From SCRATCH! Check out my blog for all the details on what parts and materials I used and how I put it all together:
https://renewablesystemstechnology.com/project-blog/how-i-built-an-electric-motorcycle

Get the plans here: https://www.resystech.com/electric-streetfighter.html

In this video I show how I built a torquey electric motorcycle from scratch in my home workshop using basic tools. I built this bike for less than HALF the price of an equally sized ZERO S (~$5000 Canadian). This aggressive looking streetfighter uses the same 24 kW (32 hp) drivetrain as the previous Cyber Trike project. The QS direct drive motor produces 250 ft-lb of instant torque, 150 km/h top speed at 120V, and the entire bike only weighs 300 lbs, making it comparable to most 300cc ICE bikes.

Power to weight ratio = 0.107hp/lb: https://goodcalculators.com/power-to-weight-ratio-calculator/

Acceleration rate using mass (136kg) and force (250 lb-ft starting torque) = 8.17 m/2^2
https://www.omnicalculator.com/physics/acceleration

0-60 time = 3.28 seconds:
https://www.omnicalculator.com/physics/velocity#:~:text=Multiply%20the%20acceleration%20by%20time,3.6%20%E2%89%88%20100%20km%2Fh%20.

For comparison, a Honda CBR 300r sport bike has 30.5 hp and weighs 364 lbs (165kg). Using the same resources we can calculate power to weight ratio = 0.082hp/lb. Acc rate = 3.439 m/s^2, and it's documented to do 0-60 in 7.8 sec.

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ROI breakdown:
Cost of build = ~$5000 total
Nominal battery capacity = 4.3 kWh
Life span of LiFePo4 cells = ~5000 cycles
Range per charge = ~80km @ 80% DOD (up to 100 km @ 100% DOD)
Grid energy cost per kWh to charge at home with 110VAC = $0.12/kWh
Cost per full charge (100 km 'tank') = 0.12 * 4.3 = $0.52
Cost per km for energy for electric bike = 0.52 / 100 = $0.005

Avg price of gasoline in Canada today = ~$1.50/ liter
Energy in 1L of gasoline = 8.9 kWh
Fuel economy of the most efficient petrol bikes = ~60 miles per gallon, or 25.5 km per liter
Cost per km for fuel for gas bike = 1.5 / 25.5 = $0.06

Electric bike energy cost savings per km = $0.06 - $0.005 = $0.055
Savings per charge/cycle (80 km) = $0.055 * 80 km = $4.40
Payback period based on full cycle charges = $5000 / $4.40 =
1136 cycles

OR
Savings per day based on driving an avg 40 km per day as a daily commuter = $4.40 / 2 = $2.20
Payback period = $5000 / $2.20 = 2272 days, or 6.2 years.

Ie: it will pay for itself in ~6 years (or 1136 cycles, more specifically), completely. LONG before the LFP battery wears out at 5000 cycles. At ~$200/kWh, I could replace the battery almost 6 times with the cost savings to be had - not that I would need to, though. I didn't factor in my time since I don't tend to keep track of it when I'm having fun, but a good fabricator should be able to build this in 2-3 weeks. At an avg wage of ~$20/hr in Canada, that translates to an extra ~$2K in labour. So technically, I guess it'll take 8-9 years to pay back the $7000 investment, which could be used to replace the battery around 7x in that time span, though it should only have gone through around 2000 of its total 5000 max cycle life span by then, so that's all $ back into my pocket, my friends (update - these calculations were based on set fuel prices before they skyrocketed so the results are relatively conservative, but should serve as a good example). 80% fuel eff vs 35%. Doesn't take rocket appliances :)

Specs:
Power: 12 kw/ 24 kWp, 32 hp gross
Motor: QS273 70H brushless hub motor
Battery: 74V/4.3 kWh LiFePo4
Range: up to 100 km's
Top speed: ~115 kph (71 mph) @ 72V, 150 kph (93 mph) @ 120V
Max torque: 350 Nm (258 ft-lb)
Controller: Kelly KLS72601
Wheelbase: 55" (140 cm)
Rake angle: 26°
Trail: 4.9" (124.5 mm)
Turning radius: 72" (183 cm)
Weight: 300 lb (136 kg)
Front suspension travel: 5" (130 mm)
Rear suspension travel: 8" (203 mm)
Front tire: 120/70-17 Shinko 705
Rear tire: 180/55-17 Metzler Karoo Street

Music: 'Dark Epic Hybrid Rock' by Pegasus Music Studio
https://audiojungle.net/item/dark-epic-hybrid-rock/28838847

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