BigTb17

I recently purchased a Hyperion outrunner and I was setting it up to install it in a Mini Slinger. I was going to use a Great Planes SS25 ESC I had lying around. The motor is brand new and this is the first time I ran it. I installed a 4.5x4 APC prop, plugged in a 750 mAh 3s lipo and started throttling it up. Everything was fine untill around half throttle when the motor started making an odd glitching sort of noise and the amperage spiked super high and the motor started heating up quickly. It almost sounded like it was cutting out and turning back on very rapidly. The battery voltage was fine, and the servos weren't glitching or jittering at all and response to throttle inputs remained solid (not a radio issue).

I decided to remove the prop and see what happened with no load. The same thing happened, but this time it happened before half throttle and still (despite no load) the amperage spiked to around 15 amps and the motor started getting hot. It seemed RPM related, not so much throttle position related. It seems like a possible timing issue, but there is no way to change the timing on the SS25, so I don't know if there are any other options.

I tried a different motor on the SS25, same battery, same Tx and Rx, and it seemed to work fine (no load). I then tried the motor I was having issues with on an E-flite 20 amp ESC and it also worked fine (load and no load). It's just that one motor with the SS25.

I haven't used the SS25 in a while and would probably lean on placing the blame there, but it seemed to work ok with a different motor. I'm just wondering it anybody has similar experience/issues or if someone knows of any timing incompatibilities with this ESC or motor. The motor is a Hyperion Z1709-06 (2100kv) 12 magnet, 9 pole.

Dr Kiwi

It is the motor. Are you sure you haven't got mount screws which are too long - shorting out the windings. No motor should ever draw 15A no-load... no matter what ESC timing you have!

BigTb17

Thanks for the reply. I usually check screw length before mounting any motor, but it's an easy thing to overlook. I have actually double checked the screws though, and they aren't even close to the windings. Also, the motor (without removing the screws or changing anything), works fine with an E-flite 20 Amp speed control. It was drawing around 10 amps at full throttle with the 4.5x4 APC prop, and was smooth at all RPMs and throttle settings. I switched back and forth between the ESCs a couple times to help eliminate possible intermittant connection issues, etc. and found the same result each time.

On the SS25 ESC it is smooth at low RPM and draws typical amperages (with and without the prop). The issue happens when the RPM starts to climb (it happens at a higher throttle setting when the prop is mounted, so it definitely seems RPM related). The motor starts stuttering really bad and jerking back and forth and the amperage jumps up. It seems like maybe not so much a motor timing setting, but rather the ESC's switching speed seems to not be able to keep up. It seems like the ESC is pulsing too soon and the motor tries to spin backwards for a split second, causing the RPM to drop drastically (and the amperage to spike), at which point it starts working properly (due to the RPM reduction) and the speed goes back up and it happens again. This happens very rapidly, causing the motor to shake back and forth. It almost sounds like it is rapidly bouncing off a rev limiter. I don't know if any of that makes sense, that is just the best way I can think of to explain what is happening [&:].

It's not a super critical issue to get the motor working on the SS25, I can always just buy another 20 amp E-flite, or swap the one I have between models. I was just curious if anyone else had a similar experience with the SS25, or any ESC for that matter.

Dr Kiwi

I've only tried an SS25 once and was not impressed... but it didn't do the weird stuff yours is doing!

BigTb17

Yeah, that's why it was "laying around" and not in a model. My biggest issue with it is the low voltage cutoff. It automatically set the cutoff at 0.67 times battery voltage when you plug the battery in. This is a problem with partially charged batteries, but it is also too low even with a fully charged battery.