CellsBattery boxView from cockpit
OwnerBarron Greig
Owner's Other EVsSun EZ3-AX Recumbent Trike
2009 Kawasaki Ninja 250R
LocationTempe, Arizona United States map
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I chose the bike with the largest frame triangle I could find to make it as easy as possible to fit the battery pack in. Pack mass is centralized to help with handling.
This is a very tall bike. I'm 6'2" and even with the seat as low as possible I'm on the tips of my big toes.
MotorCrystalyte HS3540 Brushless DC
ControllerCrystalyte C3640-CL
Sensorless 36-48V 40A

I've had bad experience with faulty Hall sensors/ sensor wiring in the past and reliability is important so I've gone sensorless this time. There is a bit of vibration at takeoff while the controller is figuring out which way the wheel is turning, then the ride is creamy smooth after that.
Batteries12 Headway 40152 S, 3.20 Volt, Lithium Iron Phosphate
15AH cell
Weight 480g per cell
System Voltage36 Volts
ChargerSoneil 36V 8A
Expensive but reliable. In the past, on other projects, I've used cheaper Chinese chargers ... but they all went up in smoke. I'm guessing some of the reliability issues of these chargers could be mitigated by adding pre-charge circuitry (basically a resistor and a switch) on their input and output. Surprisingly, the chargers I had used did not have any circuitry to protect capacitors against inrush current.
InstrumentationCycle Analyst
Top Speed25 MPH (40 KPH)
Range25 Miles (40 Kilometers)
That range is at a 20mph average with no pedalling.
If I'm patient enough to do 10mph average, again with no pedalling, then I can get 50 miles out of a charge.
Watt Hours/Mile15 Wh/Mile
18mph seems to be a sweet spot for efficiency on this setup. At that speed, on flat ground, the power consumption is 250W. At 25mph it's 2.5 times that!
EV Miles
Current:11,000 Miles (17,699 Kilometers)
    As of 4/10/2015
Seating Capacity1 adult
Curb Weight70 Pounds (31 Kilograms)
TiresI swapped out the stock tires, which had some offroad pretensions, for a set of low rolling resistance semi-slicks to help improve system efficiency.
Conversion Time5 days
Conversion Cost$1600 including $400 for the original bicycle
Additional FeaturesQuick release battery pack so that I can take it indoors and keep it out of the Arizona heat.
The efficiency, even compared to my electric motorcycle, just blows me away. I'm seeing < 1/6th of the electricity consumption for the same journeys I do on the motorcycle. While admittedly I'm going a somewhat slower on this bicycle, it still gets me to work just the same.

Assuming $4 for a gallon of gas, for the equivalent $4 electricity I can go 2000 miles on this bike. 2000 miles per "gallon" seems pretty good!

I charge the pack at my desk in work which, for that 10 mile trip, takes about 45 minutes with an 8A charger.

11/28/2014 Cracked 10 thousand miles today. Still on the original battery cells. Pretty happy with how things are going, apart from the times when I fall off!

02/24/2015 Performance of cells had fallen of significantly, so replaced them at 11000 miles.

code by jerry