So I’m looking for some advice from anyone knowlegable about this topic, hypothetically if a 5000mah 37v battery had a tested range of 15km, a 40 000mah 37 would deliver 120km range using the same single motor in theory. Now adding a motor relieves the stress on each motor dividing the load by 50% meaning they each draw less amps to achieve the same speed as the single. My question is If dividing the load by 4 and making a single 10 000mah 37v battery for each motor would still deliver 120km because of the lower needed amps in each motor, or if I would merely have insane power for 30km? @GrecoMan @psychotiller @scepterr
It wont matter if you have pack in one, or split up in four. The Wh will still be the same, and your range will too. But remember that 1 motor/ single drive, is more efficient than 4 motors/ awd…
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in general larger motors are more efficient than smaller motors so 1 larger motor should be more efficient than 4 smaller motors. However if your just adding more larger motors i wouldn’t think this should apply.
Also a a setup with 4 motors is probably heavier and will have a lot more friction from 4 sets of belts or gears.
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Its mainly because some of the energy going to the motor will end up in heat, and heat=energy.
However, with 37v 40Ah, i dont think you should worry 
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Four 6364 - 190kv powered by 40ah split into 10ah packs to each motor. 20/32 gearing and 97mm wheels. the board weighs just under 20 kg/40lbs and I weigh 160, I doubt the 4 will have any trouble pushing 100kg/200lbs. I just want to know how the displaced load will effect my riding/battery usage
That’s where I get stuck, while the belts cause rolling resistance, if I’m lowering the load to each motor wouldn’t I get less heat in my motors? Thus making them MORE efficient? Also im using lipo, so that 37 is really 41/42v
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Yes it’s enough to make a small bomb
You are right that per motor it will be more efficient, BUT since you have four, together they will be more inefficient.
Li-ions does also go to 4.2V/Cell, but we use 3.6(Li-ion), 3.7(Li-Po) because that is the nominal voltage.
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How though, with each one don’t I improve its ability to hit full speed with less drawn power(amps)? @FredrikHems
I am not sure actually. Maybe some others know…?
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I just wonder because a single motor might draw 30 amps to propel up a hill where as with 2 it would divide the load making each draw 15 instead, I’d think this effect continues the more you add wouldn’t you? @FredrikHems @GrecoMan @psychotiller
You are not accounting for losses there. You are missing the heat and friction produced in each motor which is also multiplied by each motor you add. True more motors implies each will heat up less but in the end of one motor produces let’s say 1 heat, 2 motors would produce around 0.75 heat each. Totalling to 1.5 heat wich is more. Yeah I’m using heat as a unit of measurement
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yeah but ur motor needs to overcome inertia and standing frinction everytime u acc or break. u will have more mass and friction with 4 motor and pulleys. now there is more surface area for heat to escape so it would be easier to be loose more energy. also nothing is perfectly same so there will be unequalibriam in each side of wheel=less efficiency. not to mention all the resistance build up because of extra copper mass from wires. I probably have to do more research but I think it would be similar to sports car engine. u can increase only so much of diameter of piston or add piston before it eats gas like crazy.
of course the electrical motor is much efficient so it wouldn’t be much different but it would certainly do less than just one motor.
brushless motor is at best 95% energy efficient. so in 4 motor ur lossing about 15% in comparison to 1 motor.
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So as in every comparison where both options both have pros and cons the only way to find out for certain is… Go at it… for science!!! O And measure, it wouldn’t be science then
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I like the sports car reference, aren’t most of them 4wd? you are right though in cars a 4wd uses more power than 2wd but also the given power to ground ratio grows significantly in comparison
I will just have to go at it and see I guess
most sports cars are 2wd rear i thnk. but yeah 4wd has more torque and traction but use more fuel, tho it is mechanical so not sure if u can compare.
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4wd car is a bad example cause it still only has 1 engine.
You are right that If you have 1 motor at 30A its the the same as 2 motors at 15 amps, or 4 at 7.5 amps. in an ideal world your amps for the whole board are the same and your watts will be the same.
With regards to heat,Imagine 5% of that 30A is lost as heat. 5% of 30A is more than 5% of 7.5A so in a 4 motor system each motor runs cooler. however there are 4 motors the amount of energy being converted to heat is the same either way.
Also in the real world each motor has resistance, each bearing has resistance and each belt has resistance. 4 motors and drive systems will have 4 times as much resistance to overcome and resistance costs in efficiency.
Going back to the car reference, this is why almost all electric cars use 1 large motor instead of separate hub motors in each wheel. This is also why helicopters are very common but full size multi rotors are quite rare.
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