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Old 06-25-2010 | 12:46 AM
  #29  
OhD
 
Joined: Oct 2002
Posts: 1,160
Received 9 Likes on 6 Posts
From: west hills, CA
Default RE: Battery Choice





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Limiting the throttle will not solve the problem. The readings we get on the meters are an average current. The ESC works by allowing full current to run to the motor in pulses, and throttle controls the rate of the pulses. Using the throttle to regulate the current will still let the full 94A or whatever get to the motor, just not as often.

However, if you are running 94A intermittantly, maybe it's OK for the ESC. I talked to Castle and they had me turn off my current overload protection since I fly F3A. We don't use full throttle that often, and I think the rating is max continuous current. Just double check that one as I'm fairly new at this.
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Actually the ESC switches the full voltage on and off at a constant rate (I set mine to 8KHz) and the throttle regulates the duty cycle. At full throttle the duty cycle is 100% and the voltage to the motor is essentially DC at a level close to what you measure at the battery terminals. The motor will try to run at an rpm equal to that voltage times the Kv of the motor. The current increases with load which is determined by the size of the prop, the rpm and the forward speed of the plane. If you limit the throttle, the average voltage drops and the rpm drops, so the load decreases requiring less current. So if you want to reduce the current at full throttle to save your batteries for example, turning down the ATV will solve the problem.

If you are worried about burning up the ESC that is another question. I may be wrong but I believe it is heat due to power dissipation at less than full throttle that is hard on ESCs. There is an AC component in the RMS current that ends up in heat.
Read Bob Boucher's book and see if I've got it right.

Jim