Is it possible to run a 64mm EDF with a 6 cell battery?
- Thread starter Kam5691
- Start date
Kam5691
New member
I definitely plan on changing the ESC as it won't be able to handle 6S
quorneng
Master member
Kam5691
The problem is whether the motor can handle the same fan at 6s.
To move from 4s to 6s with the same motor you would expect to use a small diameter and/or finer pitch prop to keep the amps within the motor's limit. Only if the motor was very conservatively rated on 4s would you expect to keep the same prop with 6s. The amps will more than double
EDFs tend not to be conservatively rated to start with simply to give enough thrust to fly so just changing to 6s is unlikely to end well.
You would have to know the amp limit of the motor and experiment carefully with a watt meter attached to avoid destroying the motor.
A fan will have an RPM limit too. A disintegrating fan at 65,000+ rpm can be dangerous.
The problem is whether the motor can handle the same fan at 6s.
To move from 4s to 6s with the same motor you would expect to use a small diameter and/or finer pitch prop to keep the amps within the motor's limit. Only if the motor was very conservatively rated on 4s would you expect to keep the same prop with 6s. The amps will more than double
EDFs tend not to be conservatively rated to start with simply to give enough thrust to fly so just changing to 6s is unlikely to end well.
You would have to know the amp limit of the motor and experiment carefully with a watt meter attached to avoid destroying the motor.
A fan will have an RPM limit too. A disintegrating fan at 65,000+ rpm can be dangerous.
You can certainly run it on 6S if the ESC can handle it and as long as you do not exceed the max Wattage of the motor. You will need to watch the temperature of the motor and may have to limit the max PWM of your throttle channel so you do not accidentally cook the motor. I have run "3S" motors on 6S by limiting the max throttle. Don't count on running wide open, full throttle without issues.
Tench745
Master member
Why would you run a higher voltage if you're just limiting your top-end anyway? Are you making due with the batteries you have? Trying to push the motor as close to limits as possible? Seems to me if your limit your max throttle to 3/4 on a 6s (for instance) you could just as easily run it wide open on a 4 with no change in performance.
There are several plausible uses. Sure tuning for max "safe" performance is one reason but there is more to it than just that. Watts = Volts x Amps. Higher amps means more heat. Using higher voltage means you use fewer Amps for the same watts. So in turn, less heat for the same amount of power. Heat = wasted energy. Not just the motors, but everything along the power stream. Motors, ESCs, Wiring, Batteries, etc... Cooler components are a good thing for reliability and longevity. Lower Amps is easier on the battery cells resulting in less Sag. ETC....
quorneng
Master member
I am not sure the argument is valid that a higher voltage (6s) is more efficient at part throttle than a lower voltage (4s) at full throttle and using the same motor.
The way a speed controller works the individual amp pulses on 6s will be bigger than on 4s but the gap between them will be longer. The average amps and thus the ohmic losses will be the same.
Any reduction in losses only occurs if a lower kV motor is used with 6s so at full power it produces the same power as the 4s does at full power but it does so at lower amps so lower ohmic losses.
The way a speed controller works the individual amp pulses on 6s will be bigger than on 4s but the gap between them will be longer. The average amps and thus the ohmic losses will be the same.
Any reduction in losses only occurs if a lower kV motor is used with 6s so at full power it produces the same power as the 4s does at full power but it does so at lower amps so lower ohmic losses.
That's a whole other scenario. BTW, lower KV motors have higher resistance.
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