knightmb
100 kW
I'm often asked how my bike goes so fast and usual answer is just "more power". The conversion kit on my bike is the brush-less BL 400 watt motor, which at 36V has a top speed of about 20 MPH. On my bike, the larger 700C wheels give it a top speed closer to about 22 MPH. To boost the top end speed up higher, I swapped out (3) 12V @ 12AH Lead Acid with (2) 24V @ 13AH NiMH batteries. So the power was boosted to 48V which gave me better acceleration and higher top end speed. The lower weight also gives me better range. I have done experiments with the Wilderness Energy controller to see how much it can handle.
Using many combinations of 6 and 12 volt batteries, the most speed I could squeeze out of the controller comes at 48V. Anything more and the controller just can't be cooled quick enough to prevent overheating. When the controller overheats, it will shut off, which isn't a problem for safety reasons but I don't want to press my luck.
So why not 54 volts? Same problem, you are approaching the heat limit of the controller and it's ability to cool down fast enough. Just having the bike up so that the wheel will spin, you put your hand on the controller and after only about 10 seconds of spin, the metal is so hot you can't touch it. At 48 volts, this problem does not occur, so for safety reasons, try to keep your voltage to 48V maximum. If you really want power up the bike to go car racing, you'll need another system for speed control that can handle the extra power. In all of these experiments, the motor always seems to remain cool without any problems, even when spinning stationary with a lot of power pulsing through it.
- At 36V, I get 22MPH top speed without any problems with temperature
- At 48V, I get 35MPH top speed without any problems with temperature
- At 54V, I get 39MPH top speed, but slight problems with over heating
- At 60V, I get 44MPH top speed, but the problems really start with over heating
Using many combinations of 6 and 12 volt batteries, the most speed I could squeeze out of the controller comes at 48V. Anything more and the controller just can't be cooled quick enough to prevent overheating. When the controller overheats, it will shut off, which isn't a problem for safety reasons but I don't want to press my luck.
So why not 54 volts? Same problem, you are approaching the heat limit of the controller and it's ability to cool down fast enough. Just having the bike up so that the wheel will spin, you put your hand on the controller and after only about 10 seconds of spin, the metal is so hot you can't touch it. At 48 volts, this problem does not occur, so for safety reasons, try to keep your voltage to 48V maximum. If you really want power up the bike to go car racing, you'll need another system for speed control that can handle the extra power. In all of these experiments, the motor always seems to remain cool without any problems, even when spinning stationary with a lot of power pulsing through it.
