Electric Longboard

• Power: 2750 Watts
• Top Speed: 23 mph+
• Max Distance: 7 miles
• Charge time: 1h 20min

Battery type: 2 5000 mah 4s lipo batterys in parallel
Motor kv: 190kv
Gear ratio: 2.25:1
Wheel size: 82mm
Efficiency = approx 80%

Top Speed:

R = 0.00003728226 

Volts = 2 batterys * 4 cells * 3.7 volts/cell = 29.6 volts

Motor RPM = 190kv * 29.6 Volts * 80% efficiency = 4499 RPM

Top Speed = 4499 RPM * 82mm * pi * R * 2.25 = 19.2 MPH

Max Distance:

Whr = 29.6V * 5000 mha = 148 WHa

Watt hour per mile = 21.25 (estimated based on rider weight and average speed of 8mph)

Max Distance = 148 Wh / 20.5 = 7.22 Miles

Charging Time:

Balance charge two 5000 mah battery = 10A 

Power supply output =12.15v x 47A = 564W

Balance charger output = 500W / (3.7v * 4 cell) = 16.9 A per cell

Fast Charge time = 10A / 16.9A * (60 min / 1 h) = 35.5 min +- 10 min for ramp up time

Normal charge time at 1c = 10A / (10A * 1c) + balance time = ~1h 20 min

To control the board I use a 2.4Ghz remote and receiver. The remote has a built in 500 mah 1s lipo. The controller allows for acceleration, deceleration and when not using the controls the longboard coasts. There is also another switch on the remote to control the second channel (Currently not in use).

I wanted to reduse the cost of the longboard as much I could so instead of going with a power switch I chose to use a XT90 connector shorted. Shorting the XT90 allows for me to complete the circuit which interns powers on the electric longboard. In order to avoid sparks from pluging in to 30V, I opted to use a anti-spark XT90. This special two-stage connectors put a 5.6 ohm resistor in series with the positive leads before making a direct connection and bypassing the resistor.