Ive been struggling with my most recent build (as I have been with all of my previous builds lol). No one said it was easy!
I am using an Alien 80100 thanks to the post from @Mat. I followed the waterproofing steps outlined in that thread. Started out with a hobbyking 150A ESC submerged in dielectric oil that was circulated through a heat exchanger (an artifact from a previous build with a 6480 outrunner). The motor would spin up out of the water and behaved just fine. I went for my first test ride and once under load, almost immediately the motor failed. I pulled the board out of the water and when I gave it throttle the motor would just spin slowly for a few seconds before shutting off. All while sort of shuttering and chugging.
Thinking I may have blown the ESC since this larger motor pulls more current than probably safe for a 150A ESC, I purchased a 400A Flier Boat ESC. I hooked up the motor to the Flier and I get the exact same behavior. If I hook up another brushless motor to the ESC (my TP power inrunner for example) it seems to run just fine leading me to think it is a motor-related issue. I have tried playing with timing settings on the ESC with no improvement. Also, the motor spins freely/ normally by hand.
I next tested the motor with a multimeter. Resistance across all the windings is the same (0.6, 0.6 and 0.5 ohms). Ive read this isnt a very good test and that an LC meter is the better way to go, just dont have one. Interestingly, I also tested the resistance between the motor leads and the aluminum base plate of the motor. When I do this I measure a resistance of 3.4 Kohms. Pretty sure this indicates an abnormal short? There should be infinite resistance between any of the leads and the stator mount of the motor correct? If this is bad, do you think 3.4Kohms is low enough resistance to cause an issue? Furthermore, if so, any good ideas for how to find and fix this short?
I am absolutely dying to get out on the water with this thing! This motor issue has been super frustrating so any advice would be very very appreciated! Thanks for the help!
Just in case : have you cut the motor wire or solder plugs?
If there is not a good contact on each wires on each motor phase , amps cannot get through and under load it will not work
Thanks guys. I’ll try the timing thing again and put it the 25 degrees like you suggested. I think I tried it yesterday with no luck though but maybe I didn’t try 25 degrees exactly.
That was a good suggestion about the weak connection. I did extend the motor wires and solder bullet connectors onto the extensions. To test to see if this was the problem I cut the extensions off right back to the motor leads and then attached the leads directly to the esc. Still get the same behavior. No change.
Anyone else have any ideas? Thanks for all the help and suggestions!
So I tried setting timing to 25 degrees… no luck. I also took the motor apart to see if I could find and shorts or noticeable damage. I did see one of the leads had chaffed through the heat shrink tubing I put on there. I put new heat shrink over it and tested it again. Still no luck. Same chugging behavior and then shuts off after a few seconds until the throttle is released.
Im wondering if the windings got damaged somehow. They are now buried under epoxy so it’s hard to see if there might be a short. The motor was running fine after I first waterproofed it. It wasnt until my first test run in water that the issue developed. I imagine either the water or more likely, the added current from running under load is what triggered the issue. Any ideas? Id hate to have to buy a whole new motor after spending $180 on this one and getting zero use out of it. I imagine it would be difficult to rewind after all the epoxy I buried the windings in. I imagine rewinding a motor is no easy task to begin with.
Did you remove the isolation of each wire properly before soldering? How did you do it?
It is very important, that the paint on the wires is removed to get good contact to each single wire.
3,5kOhm should be fine and no Problem. 0,6Ohm also sounds plausible.
Maybe you can post a pic of your solder joint?
Yes , as I said , took me a long time to get to the cooper of each wires , one by one, before soldering ( tried everything and finished by using sand paper)
Before buying a new motor I will do that, unsolder , sand each wires on each phases …
just to triple check after your reply, i soldered on new bullet connectors to the motor. I first stripped the heat shrink off the motor lead, burnt off the varnish from the copper wires using a torch. Cleaned with sandpaper, covered with flux then tinned the ends with solder. Then fluxed and tinned the ends of bullet connectors (xt150) filling the cups on the end of the connectors with solder and the submerging the motor leads right into the molten cup of solder. I cant imagine these connections are good enough. As for the leads going into the ESC, the solder joints look solid and are able to spin up other motors just fine.
You cannot measure the phase to phase resistance with such ohm or LC meter. You need a power supply with constant current of more than 2 Amps measured and stabilized and a good voltage meter with mV resolution. Than you can make a Kelvin Measurement with the probes on the lead and mounted independent from the current source. A VESC can measure this as well. 140mOhm for this motor is too much, 14mOhm or 0.014Ohm is more realistic.
Another test you can do is to spin the motor by another motor, drill or lathe at minimum 1000RPM with open leads. A short circuit in the winding will cause high losses.
And yes, a 3.4kOhm resistance from lead to stator is a bad sign. Please show a detailed picture of the stator, so we can help you to find the root cause.
if I remember correctly, i’m getting something in the GOhm range too between the body and the winding when the motor is dry, it drops quite a bit when i plunge in salt water… i can’t remember the values …
3.4kOhm seems on the low side though… it might depend on the multi-meter though…
Just to be absolutely certain it was not a bad connection i wired the motor directly to the esc by twisting leads together tightly. Still no improvement…
I also tried disconnecting the leads one at a time and testing it with the thinking that if one of the connections were bad, then as I tried unplugging each lead, the motor would not behave any differently when I got to the bad lead vs. when all three were plugged in. The motor behaved and sounded totally different with only two of the three leads connected and it behaved like this as I tried running off each different pair of leads. With only two leads (no matter which pair) the motor would not even try to spin but would rather just studder.
As I mentioned before, When I plug in my TP power inrunner motor to this ESC it runs smooth as silk. further pointing towards a motor issue. I wonder if I managed to fry something when testing in water or possibly knicked a motor winding during reassembly or waterproofing (following a set of instructions i found on Mat’s post)?
Anyone know what other tests I could try or what type of damage would cause such behavior???
I finally got it to turn over using 30degrees of timing, 50% start power (it was set to auto), 8khz pwm. Not sure which one of those, in particular got it going but it started spinning. It started rough then sped up quickly. Even at full speed it did not sound quite right. probably 3 seconds into it spinning it started smoking pretty badly. I let it run wide open for a few seconds after I saw smoke (either because I was so excited that it was finally spinning or because I was so angry that it was smoking). I stopped it and as soon as it was cool enough to handle I took it apart. I was hoping that I would be able to feel specifically where it got hot so I could locate the short but the entire thing was super hot. Surprisingly, I did not notice any visible damage. No burnt spots, no melted wires or epoxy, nothing out of the ordinary. There was one small area that had some white residue (likely from the smoke).
All of this would indicate some type of short right? Perhaps the windings were shorted somewhere beneath the outer windings so any damage would be buried and not visible? Somewhere underneath the white spot. What else could cause the motor to smoke?
Looks like ill be buying yet another motor from Alien. (This will be my 5th!) I may take a stab at rewinding this one as well if i can figure out how to unbury the windings from all the epoxy I put on there.
I have burned up 2 of those motors and removed the wire from both. I know what not to do. Don’t soak the winding’s in Acetone for about a day, the epoxy or super glue they use will turn turn gooey. With a lot of effort you will be able to remove a tangled mess of wire. Unfortunately the Acetone will also soften the green powder coat that is painted on the stater iron plates. The plates will begin to separate at the ends. When the plates separate, the ends are sharp. They can nick the wire insulation when you rewind it. Also if your planning on counting the wraps so you can wind the motor the same as it was, you will wont be able to tell one wrap from the others. I suggest weighing the wire and calculating the number of wraps.
