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Originally Posted by Serum
Please get that current thing out of your head. these are not 'standard' values. the current a setup takes depends on the gearing, weight and quality of the batteries.
A motor that can take 200A can run more efficient than one that can take 100, while the one that can take 100 can take peaks of 250+ (if the batteries deliver the juice)
there is not such thing as a constant current draw with rc cars.
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I'm sorry, but I think my post was misunderstood. I hate to make them any longer as they take long enough to write as is. I have never claimed current draw is static. Its a silly idea. Plus the values posted were also related to RPM. Cars by definition are dynamic (speed (rpm), accel, load, resistance, etc) and so then is current draw. If you were pulling 100A constantly you would have no throttle control (by definition) and would drain the batts in a min or so (assuming nothing caught fire first.) OTOH, I wonder if you just like to argue w/ me... :o :P
The data above was demonstrative only. At a point in time (or static load) a higher turn motor will pull lower amperage than a lower turn. Since voltage is ~fixed, total power output is lower (and so runtime longer.) Over a cumulative period of time, the net amp draw is higher, yada yada yada. OTOH, the efficiencies were very close to each other, at least for that fixed time period (all on 14 cells) that the calc generates (values listed as @ Max Eff.)
What I was wondering is eff that great of concern when talking within a range of motors of a turn or so, or at least a bigger factor to offset the gains in heat and loss of runtime (the OPs stated criteria) when going to a lower turn motor. IE, are there large eff differences in a lower turn motor running at a lesser throttle than a higher turn motor running at a higher throttle? Hopefully that clarifies my point. or maybe not. Maybe its just moot. Whatever
Either way I stick with my rec of an 8xl (I gear mine at 15/51 w. same setup OP is considering) and perhaps a 9xl if runtime/heat is a major concern (altho my 8xl only heats up to ~160F+ after several packs.) Maybe a 7xl would run cooler, just seems counterintuitive, but I just haven't seen controlled data either way.