On my way home last night, I kept an eye on the DrainBrain's Watts readout and noticed it going over 2,000 watts on several occasions. This is a huge amount of power considering the motor is rated nominally as a 500 watt motor! I need to limit (somewhat) the amount of power going to the motor to not burn it out. Speed is important, but longevity and safety of the motor is even more so! It's amazing to think that the controller is only rated for 35 amps which doesn't sound too significantly different than my current 22A controller, however, the power difference once you add the higher voltage (72V vs. 48V or 36V) is really dramatic. With the battery at 72V, 2000 Watts is only 28Amps!
Of particular note was the fact that I rarely ran at WOT (wide open throttle). Instead, feathering the throttle so as to not overexert the battery. I am currently running with the 6 Bosch Fat Packs wired as 2S3P configuration to achieve the nominal 72Volts needed.
In this configuration (2S3P), I was able to get to work and home but did notice that the batteries were essentially exhausted. The DrainBrain was showing between 62 and 63Volts for my BFP and the controller was cutting out power by cutting power in pulses to the motor. I need to wire the additional 2 BFPs I have in order to increase capacity. I'm also planning on testing each BFP for capacity since they should give me 2AH at a minimum each and I'm only getting around 1AH each. YPedal has a nice light bulb discharger (LBD) that he uses to test battery packs.
I need to add a thermometer to the motor to keep an eye out so as to not overheat it too badly. It was very hot to the touch on my way in and I didn't have time to check it when I got home last evening.
More later,
Ambrose
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