medusa 36-60-2000 too hot?
 

I just got done testing my new 8ight conversion with an MMM and medusa 36-60-2000 on 4s (2, 2sSMC 6000mah 28c). My gearing is 15/48. I just messed around in my parking garage, nailing the throttle, just trying to test out the system. However, my temps were hitting 180 for the motor, 115 for the esc, and 80 for the batteries after about 10 minutes of running. Ambient temp was probably around 75 or so.

This seems too high for this motor, especially after doing some research and finding that the majority of people running this setup have no problems. Could I be over-geared? I hear that 13 or 14t pinions are usually the way to go, but I wouldn't expect that high of temps with a 15t. From what I can tell, there is nothing binding and everything else seems to be in working order. I am planning on racing and don't really want to lose much top end by drastically undergearing my buggy.

Would the RCM heatsink help out a lot, or is that just a bandaid fix? Could I have a bad motor?

Thanks for the help!

Update:

Well, I figured out that my spur isn't a 48.. it's actually a 45. So, I believe that I am overgeared. I ordered a medusa heatsink (RCMs were out of stock.. bummer) and a smaller pinion (13t). hopefully, this cures some of my woes.

That should cure your heat issues. If not, could be one of the wire leads coming out of the endbell. Depending how old your motor is, the wires can fray and cause shorts which can cause overheating as well.

What tires are you running?

You can try that, but I would say to gear up actually. You are not carrying much of a load on the esc or batts, so loading the motor up more often makes those components warmer but can often cool the motor down. Try the 13 since its coming, but if you continue to have probs try going the other way.

Crimefighters.



The wires do look a bit frayed (got the motor used), but they don't seem to be shorting.

Finnster, that is an interesting idea. I never thought of gearing up. I only have a little experience, but does aren't the temps I reported for the batteries and esc normal? I am not understanding why gearing up would be better for temps. From what I have read around the forums, 45/15 gearing is a little high from what people are reporting.

When the motor temps are wayy higher then the esc/battery temps then that can be a sign you are undergeared.

The reason I ask about tires is because the tires affect gearing quite a bit. You must be running buggy crimefighters? If your tires are too small, big, or heavy they could cause temperature problems. Even if you're running MT tires they could balloon more causing a higher overall gear ratio.

As a primer


Could be your driving, could be the terrain, too light CD fluid, maybe tires, etc. Either way, do what works for you. If the motor is lightly loaded the efficiency can drop, so you waste more power as heat (even if total power is less.) Could be a number of these things. Something to keep in mind.

UPDATE:

Sorry it took me a long time to get back, but I have been keeping pretty busy.

Anyways, to make a long story short: my motor is dead. I think it must have been the frayed wires or just an old motor (used). I was using it in my 8ight, and I had added a Medusa heatsink in the hopes of reducing the temp. However, after about 5 minutes of medium to hard bashing (about 75-80 degree ambient temps), I started to get really bad cogging with a top speed of less than 10mph and maybe 15% power. I stopped running and checked the motor temps 190! I can't remember the esc, battery, but they were within the norm.

After stopping, I checked the motor and noticed grayish black material falling out of it. There was a good sized cylindrical chunk that fell out as well. I also believe one of my magnets came loose. Anyone know is this motor is toast? Anything I can do?


I have pictures, but they are at home. I can post them later. Thanks

Call Medusa and see what they say. Might not be under warranty since was used after all, but they might offer a reduced repair price...

Sounds to me like the motor got too hot one time and it demagnatized the rotor. It then turned the windings into a big short which just got really hot and further destroyed the motor. Am I right?