No Power

[Frank Skilbeck]

Motor in a friends plane was behaving very anaemic, producing very little power. We changed the ESC and checked the battery and this made very little difference, so we ended up hooking in my telemetry and found the motor was only drawing 4 amps instead of 30 amps.

We've fixed it, but can anybody guess what the problem was ? (no prizes i'm afraid )

[Nicky Strahan]

Prop reversed?

[Denis Watkins]

Almost the same area,

But the prop drive shaft was not tightened up?

[Chris Walby]

Change the throttle setting in the TX, Wrong lipo?, Might be able to re-span the ESC so not give full range, motor reversed....

Or as you say "motor not developing power" as power is a product of volts x amps, it must be volts as current is a product of voltage/resistance (which you can't change!)... simples

[Geoff S]

Chris, it's also dependent on load - in this case turning a prop

Geoff

[Dane Crosby]

Low Kv motor with a small high speed prop.

[Gary Manuel]

I'll go for prop not tightened onto the shaft.

[Frank Skilbeck]

OK, some close above, the motor had run well and given plenty of power, so we were perplexed and decided to strip the motor down for inspection, it was perfect except the outrunner portion (the bit with the magnets) was slipping on the shaft! sorted out the grub screws which were difficult to remove and then re-tighten it all, and bingo back to full power. I'd never seen that before, must admit it ran a lot quieter after too.

[Dickw]

I have seen something similar with an inrunner when the shaft started turning inside the magnets. Very difficult to diagnose as it all felt OK when turning manually and only slipped under power. A lot harder to fix as the shaft was glued in, so a factory repair job.

As you say Frank, amps volts and rpm measurement can be very useful at times like this.

Dick