Going into this e-powered V-twin project I knew I'd face some obstacles & I wasn't wrong. The biggest hurdle to overcome was my lack of knowledge concerning all facets of current battery technology, etc. and I'm still working through that, while building on. I've had a lot of e-mail, calls and personal observations from a lot of knowledgeable cycling enthusiasts, not connected with this forum about "how are you going to handle?" questions mainly dealing with heat issues and reaching power goals without burning things to the ground or at least frying components. It all comes back to heat. I thought I'd share some of my thoughts on the topic here, dealing with what I've got rather than why I've got it, chose it etc.
The motors, 2kw, 3kw & 4 kw direct & brushless...running 72 volts. That's where I'm at motor wise. The motor controller 72v 100 amp and the BMS also 72v. 100 amp. the battery pack, yet to be built, 72v. 20s &5p....100 amp plus max potential but dialed back to 80amp bursts. So yes I've been thinking about heat in an air cooled package.
The photos show that I've left the motor case open on both ends of the case, with room around the various case covers to flow fresh air. The bottom of the case is also open for internal air flow as well. I've not drilled the direct drive motor cases for ventilation but that's an option if required. Of course the hardest thing to do is also the easiest to implement and that's just self control in refraining to max out the limits. The 4kw @72v. & 65 amp is 4.68kw which is 6.22hp and that, while not continuous is sustainable for 10 to 15 minutes, and that would drain a 20 amp hr. pack in a hurry. using 80 amp only bumps this to 7.66hp, but an extra 1.4hp required for a few moments could save ones life in traffic situations. Getting hit from behind has always been a big concern in any vehicle. A motor bike stopped and underpowered makes that my biggest concern in traffic. I'll trade speed for torque any day!
Rick C. just trying to stay cool!
The motors, 2kw, 3kw & 4 kw direct & brushless...running 72 volts. That's where I'm at motor wise. The motor controller 72v 100 amp and the BMS also 72v. 100 amp. the battery pack, yet to be built, 72v. 20s &5p....100 amp plus max potential but dialed back to 80amp bursts. So yes I've been thinking about heat in an air cooled package.
The photos show that I've left the motor case open on both ends of the case, with room around the various case covers to flow fresh air. The bottom of the case is also open for internal air flow as well. I've not drilled the direct drive motor cases for ventilation but that's an option if required. Of course the hardest thing to do is also the easiest to implement and that's just self control in refraining to max out the limits. The 4kw @72v. & 65 amp is 4.68kw which is 6.22hp and that, while not continuous is sustainable for 10 to 15 minutes, and that would drain a 20 amp hr. pack in a hurry. using 80 amp only bumps this to 7.66hp, but an extra 1.4hp required for a few moments could save ones life in traffic situations. Getting hit from behind has always been a big concern in any vehicle. A motor bike stopped and underpowered makes that my biggest concern in traffic. I'll trade speed for torque any day!
Rick C. just trying to stay cool!
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