Wiggy

What can be used to reduce the 11.1 volts from a 3 cell LiPo pack to approximately 9.6 volts?

I want to use a three cell LiPo pack with my IPS motor but 11.1 volts is too much and 7.4 makes it a bit weak.

Some of the guys locally are putting two diodes in series between the pack and the ESC but this doesn't sound right to me. They get "5 amp" diodes from Radio shack.

e-bird

2 different facts. Putting a diode in series will drop the useable voltage .7 volts per diode so 2 diodes is 1.4 volts but limiting your throttle travel wwill do about the same thing. And no power loss in the diodes or heat. Now a voltage can also do it if you can find
one big enough without yoo much weight. Normaly voltage
regulator are for BEC's or chargeing the battery. CU
http://www.national.com/catalog/AnalogRegulators.html

Wiggy

The problem with limiting throttle travel is the BEC in the ESC. This is set for 8 cell max and at 11.1v the ESCs are getting hot and failing. I also know that some ESCs "learn" the throttle curve of the transmitter thus negating this option.

It seems to me with all that can be done with electronics these days there would be an easy way to reduce this voltage without converting it to heat.

Wiggy

Greg Covey

The 8-cell GWS ESCs work fine on the 3-cell Lithium pack voltage. The real key is reducing the current draw in both the ESC and motor.

This can be done in several ways like throttle management (previously suggested), prop size reduction, and increasing the gear ratio reduction.

Matt Kirsch

My Feedback: (21)

The "juice" that makes our electric planes fly is a precious commodity when that plane is floating around out there, even with LiPoly technology. Why add further inefficiency, complexity, and expense to the system by trying to regulate the voltage?

IMHO, a voltage regulator in this application is not practical. It adds weight. It's added expense. It simply throws away a bunch of electricity that would be better used to fly the plane. It's another point of failure.

I haven't even mentioned the fact that no such commercial product exists. The regulators you commonly find at your local Radio Shack are for 5 Volts, and they're only good for a couple of Amps at most. You aren't going to find anything useful at any hobby shop either. This means you'd have to find an appropriate circuit diagram and build your own.

Wiggy

Even though these are not the answers I wanted to hear, I appreciate the suggestions. I do not want to convert the "excess" voltage to heat.

Thanks for the suggestions.

e-bird

Think of the battery as a big jug the (esc is kind of a voltage regulator) if you turn the throttle full on that would simular as turning the jug upside down somewhere in between you need
a hose out of the jug for the right power for your prop to turn
at the right speed what ever that might be 1/4 to full throttle
will open or make hose bigger. unless you turn it on it is not wasted battery engery . Just like your trottle in your car at 200mph it take about 1/2 per mile if you go 30mph then it 1/30 of a gallon. CU