Higher voltage = lower current (amperage)
most of the components on the vesc are limited to 60v, but we need to leave some headroom. the components weren’t meant to be pushed to the extent that 12s pushes them.
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The voltage limits are hard limits; can never exceed and each individual part has some variance in manufacturing tolerance, so just because one works up to voltage X doesn’t mean another will work to voltage X
The current limits are not hard limits at all, and are only limited by heat … so the parts can’t get too hot. If, for example, you were to cool the unit more agressively, or tune it down in software, you could adjust current performance. But not voltage maximums.
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When you say vesc, are you referring to both the focbox and the vesc 6?
this is not a thing. can people please stop saying this.
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wait what? please explain.
higher voltage does NOT equal lower current. in most normal applications higher voltage actually equals higher current. its ohms law V=I*R so what no one ever mentions is R! you actually need to change the load in order to get lower currents from higher voltages.
so what you should be saying is: similar torque can be had from a higher voltage with lower current if you use a lower kV motor.
however with the same motor and un governed torque you will always draw more current with more voltage.
this “higher voltage = lower current” thing is missing half the equation and its pretty misleading to the noobs.
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ahh yea ok. sorry. should be more clear next time
so this is right? higher voltage + lower kV motor = lower current?
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yeah. don’t worry. its not just you… I see that +V = -I thrown around on this forum daily.
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I feel this is a bit of a misinterpretation of Ohm’s Law and might be confusing to some. The relation is V=I*R, which is the voltage drop across a resistor. So yes, for a constant R, higher current equates to a higher voltage drop
But what we really care about is power. Power gets things done; resistance does not.
The important equation for our purposes is: P=V*I
Simply put, less current is required at a higher voltage to achieve the same electrical power power output:
- 2000W / 37.0V = 54A @10s
- 2000W / 44.4V = 45A @12s
But really… higher voltages just give you the ability to produce more power. 12S can produce 20% more power than 10S at the same current. Using the same example, 54A on 12S produces 2400W
Back to the topic at hand: 10s4p vs 12s3p
10s4p will have better range and less voltage sag than 12s3p. Because at the end of the day you have 4 more cells and about 10% more watt-hours, as others have said
Example: At 2000W, 10s4p would draw 13.5A/cell, while 12s3p would draw 15A/cell
So the current draw per cell is actually less on 10s4p than 12s3p, which means slightly less voltage sag. And it has higher capacity (higher watt-hours), which means slightly better range.
If you wanted a fair comparison, assume both battery configurations are limited to 15A/cell. In that case, the 10s4p battery can produce 2222W, while the 12s3p battery can only do 2000W. So the power difference between the 10s and 12s (from above) is actually offset in this case, since you are really comparing 40 batteries to 36
Long story short, 12S can produce more power than 10S for the same [total] current. But a 10s3p battery can produce more power than 12s4p for the same per-cell current
Overall the difference is not worth stressing about… go ride your skateboard 
TL;DR: More batteries = More better
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I think what @GrecoMan meant was that for the same watt output at higher voltage the current has to be less than current at a lower voltage 12v * 10a=120w 10v * 12a=120w So however many watts you draw at a higher voltage it’s lower amps than lower voltage
We should all start over and call this thread “Pros & cons: 10S6P vs 12S5P” so the number of cells is the same. Because I think that’s more in-line with the OP’s intent. More cells is always moar better. But for the above, I’d use 10S6P
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This is why I went with 10s for vesc/focbox the erpm limit can easily be surpassed using 12s which would fry your shit. Also even being too close to the erpm limit can be bad as people have reported malfunction under 60 000rpm as well so it’s important to leave headway as I believe it was @GrecoMan said.
what about the vesc 6?
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The vesc 6 is rated for 20amps higher continuous draw than the torqueboards/diy or focbox controllers so in theory they could handle a good bit more than the others but I don’t trust labels do you? So even still I would probably stick with 10s but that’s just me sticking to the safe side. Im sure it’s possible that one could handle the added power though @lennylogs
Plus you then have to think about your wire and connector limits, xt90 cables are only rated for 90amp continuous, I’d say that 10 amps below is cutting it pretty close and might cause some sag/power loss due to heat
JFYI the standard vesc 4.xx hw can only take 27a continuous. I dont know if the vesc 6 actually can handle 80a continuous, but I am pretty sure it can handle more than 20a compared to the standard vesc 4.xx hw.
Comparing 10S6P to 12S5P I would choose 12S because of less current for wire and VESC at the battery circuit while having the same max power and higher possible top speed. In this szenario the current for each cell is the same. And to reach the same top speed you can choose a lower kv motor which results in more torque and by this less average current at the motor. With 10S4P or 12S3P it depends if you want speed or range.
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It’s interesting so many people are saying this considering how many 12s builds you see on here that at least seem to be running well…not to mention all the people selling 12s builds as well. I wonder what esc boosted uses since they have a 12s battery.
I think I’ll go with 10s4p as it’s my first build and I don’t want to risk ruining my focboxs. Plus 25/30 mph should be fast enough (having said that, the 22mph top speed on my boosted definitely leaves me wanting more)
Huh, what? I havent said anything about voltage? The only thing I have written here was about amps…
I wanna set some things clear. As far as my Physics Knowledge goes
=> the VoltageXCurrent is a Power from the BATTERY, Not to the MOTOR.
This is because of ‘Back-EMF’. And Back-EMF is proportional to Angular-Speed, by Faraday’s Law.
So, actually, Battery Voltage is Divided into 2 Parts: “Back-EMF” and “Internal Resistance*I”
The equation is now : " V_bat = (K_u [V/(rad/s)]) x w [rad/s] + i [Ampere] x r [Ohm] "
So, with ‘Higher V_bat’, you can Either put that amount into ‘Rotational Speed’ OR ‘Current’.
-> Higher Voltage = Higher Current (if, same Rotation-Speed). >> More Torque. -> Higher Voltage = Higher Rotational-Speed (if, same Current). >> More Speed.
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