MM temps in Traxxas Slash

[Robert]

I'm running the MM5700 in the new traxxas slash. I have a 15t pinion and the stock spur. I belive it's an 86 48pitch. My temps are about 170 With some light bashing in the dirt and a few speed runs on pavement. I was running a 7 cell gp3300. This seems to hot for me. I want to run a 3s lipo but now I'm scared I'm just going to fry the ESC. Does this seem right or do I have an issue with the new ESC? I've seen several posts with people running lower temps than I and I certainly didn't bash it hard yet. Is the 3s going to make it even hotter? Should I get a fan? I was really expecting more from this system.

[BrianG]

3s will make it hotter unless you gear down to lighten the motor load. I would have thought that any of the MM motors would be too small for something that is fairly large. If going to 3s and gearing down doesn't help, you might want to consider getting an L size motor. 3s on either an 8L or 9L should be fine. The 9L would be better if you think you might go to 4s in the future.

Also, use an external BEC on 3s...

[MetalMan]

3s Lipo would be better suited to the 4600 than the 5700, I think. Is that temp you mentioned on the ESC or motor?

[Robert]

Temps on both were the same. I sold off my BL emaxx due to constant temp issues. I really want this one to work. I'll drop the pinion to a 14 and see what happens. I was hoping to keep some top end. I can understand the motor being to small, will that impact temps on the ESC?

[BrianG]

Yes, a motor that is too small can definitely cause ESC temps to go up. It's all about matching the motor/ESC/battery for the application.

[Robert]

That's acceptable news. If I go with a cheap feigao do you think temps on the ESC will still be high or should I just bite the bullet and get the neu?

[BrianG]

A properly selected Feigaos will still get warm after a while, but not nearly as bad and/or as quick as a motor that is too small.

[Robert]

I dropped to a 14 pinion and temps are better.I don't have access to GPS or radar so I couldn't tell top speed but it seemed faster? I have a 13, I'm trying that one tomorrow and will report back. It's alot more fun when you don't have to watch the temps. I'm glad I didn't get the 7700. I'm going to assume that the 4600 would be the better choice for this vehicle.




skellyo, how are your temps running the sidewinder?

[MetalMan]

How is (are) your battery(s)? If it is faster when gearing with a smaller pinion that tells me your batteries can't keep up.

[skellyo]

My motor was around 165F after 30 minutes of running in 90F ambient air. The ESC was around 105F. This is geared 18:86 for a top speed around 32-33mph on 2S Lipo. This is also running primarily through the short grass in the vid I posted in the other thread.

[BrianG]

Or the high current (from overloading) is causing a big drop in kv. It does make sense that voltage will drop too...

[Robert]

Batteries are older and have been well loved. I don't mean babied. I mean well used. I did get an occasional cog. I figured that was the batteries having a hiccup. Yes it did seem quicker with the smaller pinion. If the batteries are on their last leg would it run hot with the larger pinion?

It was about 90 here today also. My ESC was much hotter than yours.

[BrianG]

Tired batteries would get pretty warm and would drop more voltage under load.

I would also check airflow to the esc. I noticed a significant temp drop on my mm in my maxx when i turned it sideways so the air can flow thru the fins and not just the face of one fin. + the body on the slash is much bigger than a regular stadium truck so it might be impeding(spelling) airflow.

[Robert]

Tomorrow I'll drop in the 13 tooth and see what happens. Perhaps it's the ESC. I don't get the arming tones. I figured that was because the caps were holding the current but it also doesn't appear to enter programming mode normaly. In fact I haven't been able to set it to the remote aside from the first time. When I hold full throttle and turn it on I get a solid red light. Let go and I get a green. I don't know what to think.