thingstodo:
Sounds like a great idea to have a "universal brain" one could plug in like that, for all the reasons you list. I like the idea of re-using already "safety rated" enclosures!
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The motors will be set up from the factory.
I just figured you would run 2 of the same motors.
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oil pan 4:
Well, yes, 2 of the same motor. I was wondering how similar they had to be, or whether "factory tolerances" are good enough as-is. Sounds like I should reasonably carefully set up the main cables running to each motor so the per-motor phase resistances are basically equal.
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With 1 motor driving each axle directly, the setup would have fewer friction losses and possibly the weight penalty would also be lower.
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cRiPpLe_rOoStEr:
True, but my target application (dreamland, I know, lots of built in assumptions in terms of arranging recharging, etc.) is off-road. Getting sufficient torque to the one wheel that has decent traction to get over that rock while still retaining a sufficient speed spread in the same motor seems quite a tall order. Linking two motors across one axle with a "locker" of some kind (basically a normally open clutch between the two) halves the per-motor torque requirement, but it's still pretty difficult to get it.
Were I building a vehicle that would never go off-road, 1 Leaf setup per end or 4 geared motors, 1 per corner would work fine. If I build what I want - an FJ-40 - it must retain at a minimum the off-road ability of a stock driveline, so 6500 ft-lbs at the axle in low-range-first-gear. That got me pretty much everywhere I wanted to go off-road before, the limit was traction and ground clearance (no lockers at the time, and no lift). Freeway specs are modest, so not difficult to achieve.
freebeard:
Yes, it looks like EVTV has a lot of the bits I'd need to splice some OEM goodies together. One of these days I'll have to watch some of the videos there, too.
General question to all, sort of off my original topic: What are the safety implications of using two complete Leaf battery packs, connected in series, to give ~800V to MPaulHolmes' 200kw inverter? If the + and - from each pack is fed directly to the box the inverter lives in, then aside from touching the wrong two battery posts, or chafing through both the + on one pack feed wire and - on the other there should be no voltages exposed that are higher than a stock Leaf. There'd be contactors within the inverter box to split/combine the packs based on whether the car is in "charge" or "drive" modes, and the packs would likely be charged "in parallel" (either two packs and two chargers run separately, or two packs paralleled on one charger).
I'm basing that query on the idea that doubling the voltage *roughly* doubles the RPM at which peak torque can be maintained from a given motor. Other than the additional losses from running the motor outside its' design envelope, that should give roughly double the power at stock current levels. Extrapolating from the existing ratings, and using stock current levels, that's still ~207 ft-lbs 0-2200RPM, ~192 ft-lbs 2200-6000 rpm, ~215hp 6,000rpm to 10,300rpm (keeping stock redline). If we take 200kW input to the drive, and take a 90% drive/motor efficiency, we can get ~241hp at 6000rpm on up, so ~211 ft-lbs 0-6000rpm calculating backwards. The motor would still happily run at 107hp/7,000rpm constant rating, which is "enough" for long-haul and hill-climb needs. (battery capacity limited unless fancy range extensions are figured out. Probably a pickup truck and a trailer...) Higher if cooling can be improved - and one motor is easier to cool than 2.
Thoughts?