Capacitor For MM 4S

[Matthew_Armeni]

Just upping the voltage will not change the amount of amps the motor will draw, a 9XL draws the same whether on 4s or 5s (if I'm not mistaken, I'm pretty sure I'm not) it will just perform better on 5s.
Someone please correct me if I'm wrong about this

[sikeston34m]

Originally Posted by Matthew_Armeni

Just upping the voltage will not change the amount of amps the motor will draw, a 9XL draws the same whether on 4s or 5s (if I'm not mistaken, I'm pretty sure I'm not) it will just perform better on 5s.
Someone please correct me if I'm wrong about this

I would like to take a stab at this one.

Watts=amps X Volts

Let's look at two setups both geared for 40mph top speed.

#1 runs on 4S

#2 runs on 6S

Both cars accelerate at equal rates and in a race would be completelyl equal.

The idea that higher voltage setups draw less amps relates back to Watts = Amps X Volts

Since both cars are equal, both motors are putting out the same total watts of power.

#1 is drawing let's say 60 amps at top speed. 4S lipo will be about 14.8 volts loaded. 60amps X 14.8 volts = 888 Watts of motor power.

#2 being the equal to #1 that it is, will be drawing this kind of energy to produce the 888 Watts of power. 22.2 volts under a load on 6 S
888 Watts = 40 amps X 22.2 volts

What can we conclude from this information?

If you noticed, the word "equal" was used alot in that description. If you take #1 setup and just put it on 6S without making any other changes such as gearing, it's going produce more power and draw more amps.

If your goal is to lower the amp draw of a setup, you must change the gearing to lighten the load (resistence) on the motor so it will draw less amps.
This could even involve using a different motor of a lower kv to reach this goal.

thats what i thought, the 9xl is a better 5s motor , but it runs good on 4s

i will have to get some smaller pinions and try it

[Matthew_Armeni]

Thanks! I never really thought about the re-gearing though it should have been ovbious, doh! Now, is there also a point at which increasing voltage and re-gearing will no longer be beneficial? I mean at some point the motor will be spinning too fast and cause overheating, right? Is this where finding the sweet spot of the motor comes in? Around 35K is what I've been reading on here.

But, the 9XL doesn't draw that many amps anyway, entjoles- what are you hoping to get by running 5s? I'm guessing more top end.

[sikeston34m]

Originally Posted by Matthew_Armeni

Thanks! I never really thought about the re-gearing though it should have been ovbious, doh! Now, is there also a point at which increasing voltage and re-gearing will no longer be beneficial? I mean at some point the motor will be spinning too fast and cause overheating, right? Is this where finding the sweet spot of the motor comes in? Around 35K is what I've been reading on here.

But, the 9XL doesn't draw that many amps anyway, entjoles- what are you hoping to get by running 5s? I'm guessing more top end.

Yes, there is a point where just changing the gearing will no longer be beneficial.

Let's go back to the two setups I mentioned that were equal in performance with just a few things different to make them perform the same.

#1 on 4S, the motor spins at 35k but has the same gearing as #2. (2365 kv motor drawing 60 amps at 40mph)

#2 setup on 6S spins the motor at 35k. (1577kv motor drawing 40 amps at 40mph)

With the two setups equal in top speed, what are we hoping to get? Less amp draw usually means less heat build up in components. Heat build up is like an Energy leak. It's like running a battery powered electric heater. We spend that energy to make heat instead of motor power.

#2 setup will run longer on each charge and probably tend to accelerate faster than setup #1 because the lower the kv of a motor, the more torque it makes.