My 2nd Project Kmart bike with 500w cyclone kit

[dazzassj6]

hey guys heres my new bike i just finished building after 8 hours of frustation and a whole week of preparation.

Its a female Kmart mountain bike 26" wheels mounted with a 500w cyclone with a 24v 20ah 13C LiFePo4 batt. Flat speed 30km/hr (estimating) pedal: 35km/h (estimating). ITs a bike built for my cousin. Spent $817 AUD total ! $600 for kit+battery, $150 kmart bike, $40 bike shop labour to change axle and to add some extra chain and a $27 rear rack for the bike.

Im disappointed on the top speed, i thought it can go 50km/h! but wen i bought it, it was labeled 2500rpm REDUCED to 300rpm. And for some reason the battery drains all the power in less than 5 kilometers!!!!! The motor is quite hot aswell! I dont know why the motor is drawing so much power and its not even going that fast. I dont go uphill much either. Its suppose to be a 20ah battery! Anyone know why?

Heres some photos

 

[lawsonuw]

My best guess on the efficiency issues you're seeing is that you're keeping the motor in too high a gear. Gear and motor noise can give you some indication of how hard the motor is working, and if you're pedaling with the motor your cadence will vary in lock step with the motor's speed.

First test is to get in a low gear and pedal fast enough so that the full throttle motor can't keep up with your pedaling. This is the free speed of the motor.

Next test is to change gears such that you are pedaling half as fast as before. (get a lot of space for this test ) This is the peak power speed at full throttle. The motor's efficiency is about 50% at this point and only gets worse as the motor slows down. Therefore pedaling slower just wastes power from your battery.

The cursing pedal cadence with the best power/efficiency compromise will be about halfway between these two cadences. If this is too fast to pedal, get a larger sprocket on the cranks.

All this while you should be listening to the sound from the motor. Shouldn't be too long until you can keep the motor in it's optimal rpm range just using motor sound.

Marty