Esc seems to be overheating...suggestions

[JWExperience]

Hi all, brand new to crawlers and so far I enjoyed building my scx10 ii. I tried to keep it a budget build since I wasn’t sure if I would like this crawling stuff. I picked up a opened kit for $200 and installed a sensored esc/motor that I found for cheap on eBay. The motor is a 3900kv Novak which is higher than I wanted kv but it was $30 and the esc is a 120amp Hobbywing Quicrun which I got for 50$. I had a futaba servo which is on the weaker side but it was unused in my parts bin until I get a better servo. I’ve also been running 3s with stock driveline and gearing.
The problem is that I run for a 3-5 minutes and the esc shuts down. If I turn it off and back on, it runs again for a minute then shuts down. The steering still works, just no motor. The esc is warm/hot to touch but not burning hot.
I was thinking of installing a bec but don’t want to start throwing money at it without asking more experienced people. I changed the lvc from 3.4-3.0 volts with no change.
Thanks for any input!


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[Crawler Cads]

The 10bl120 retails for around that so was it a new ESC?
You need to buy a program card/box for it as they don't ship with one on that series and it'll need programming.

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[JWExperience]

It was a new esc and I programmed it using the red button on the switch unless there’s more parameters that I can’t address using the manual method. I added some drag brake, lowered “punch”, set lvc at 3.4 then back to 3.0 volts.


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[Ninomaniac]

Set lvc back to highest, your batteries will be grateful.
ESCs don't like crawling speeds, they're most efficient at WOT. However a 120A ESC shouldn't thermal shutdown in a couple of minutes... does it run smooth? No cogging?

Your ESC has a linear 3A BEC, which may be fine for 2s use, but 3s may be causing problems making it shut down.

Weird.

[2mtech]

Do you have a 2s battery you could try running it with to see if you still have the issue?

[Ninomaniac]

Or try running 3s back and forth with no servo

[Natedog]

Originally Posted by JWExperience

... installed a sensored esc/motor that I found for cheap on eBay. The motor is a 3900kv Novak which is higher than I wanted kv but it was $30 and the esc is a 120amp Hobbywing Quicrun which I got for 50$. I had a futaba servo which is on the weaker side but it was unused in my parts bin until I get a better servo. I’ve also been running 3s with stock driveline and gearing.
The problem is that I run for a 3-5 minutes and the esc shuts down. If I turn it off and back on, it runs again for a minute then shuts down. The steering still works, just no motor. The esc is warm/hot to touch but not burning hot.

What pinion and spur gears? Probably over geared if it's stock gearing for that kv motor. I prefer brushed motors for crawling, cheaper, less finicky, usually better low speed control. Hobbywing WP1080 esc, Traxxas 550Titan 21T motor, 3s lipo and gear as needed. I usually run a separate BEC too.

[QuesoDelDiablo]

I'm saying gearing.

3900Kv is HUGE in a crawler/trail rig, I run 2200 and that still feels a little too quick on 3S.

With taht high of Kv and running stock gearing, I think you may be pushing the motor/esc too hard.

Try dropping down to an 11-12T pinion.

Could be an issue with running 3S as well - every Novak motor I've encountered (admittedly that's not a huge number) was specified to 2S only.

[Rekreant]

Sounds like a faulty ESC. I run my HW1080 in 95+ degree heat and it doesnt thermal shut down, thats on 3s with stock gearing.

[JWExperience]

I’m thinking of ordering a 11 tooth pinion and bec. The motor runs perfectly smooth until the esc shuts down. It’s a sensored setup so I can creep along pretty slow as is but if I start crawling and climbing I’ll prob need the 11t anyways to have better control. I’ll prob also play with the expo on my remote to ease into the throttle.
I only have 3s batteries at this point and am thinking that this combined with the lack of a bec may be why it’s heating up. I’ve had 1/10 4x4 sct trucks with lower rated esc’s on 3s and not had any issues so I’m surprised that this one can’t handle this. 2s batteries would prob be better. Thanks for the responses.


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[Natedog]

Pass on 2s....run 3s it's just better and more fun.

Yes, buy 11T pinion and BEC, get a Holmes Hobbies RX Bypass harness while you're at it.
https://holmeshobbies.com/electronic...s-adapter.html

[Stormin2u]

Natedog's council was spot on. if gearing your rig down doesn't cool your ESC you might consider a brushed motor. For scale crawling most like a 20T-35T brushed motor. I've run 20T/3s in my scale trucks for years and my ESCs never get hotter than nicely warmed, just saying.

[Rekreant]

If you are inclined or already own a soldering iron Id say you can do it yourself and save the 7$+shipping of a bypass.

[JWExperience]

Either way I have to solder the power wires to the batt leads correct? Adapter or no.
I appreciate the responses guys and I’ll order those parts up Natedog. Thank you!


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[dacaur]

My money is on the battery....

If neither the motor or the ESC are hot, I would suspect the BEC cant handle the strain, however, a BEC overloading would generally not leave you with steering but no motor... Normally losing motor but keeping steering is a bad battery. You didn't mention what battery you are using, mah, C rating and age...
If you have your system overgeared a bit on a crawler, your motor and esc can probably handle it, even if its a bit higher gearing than is "ideal", but a marginal battery might not be able to handle the extra amps...

[mewalsh100]

As the mantra goes...GEAR DOWN, VOLT UP!

[Natedog]

Originally Posted by Rekreant

If you are inclined or already own a soldering iron Id say you can do it yourself and save the 7$+shipping of a bypass.

Yes you can, but HH harness is nice, premade and inexpensive.

Originally Posted by JWExperience

Either way I have to solder the power wires to the batt leads correct? Adapter or no.
I appreciate the responses guys and I’ll order those parts up Natedog. Thank you!

You either solder lead wires with jst plug to esc power wires and install jst plug on bec with good crimping tool, do all my truck same way, that way everything plug in and is easily interchangeable.

Originally Posted by mewalsh100

As the mantra goes...GEAR DOWN, VOLT UP!

X2

[JWExperience]

Ok thanks for the tip on the adapter. The battery is a brand new 3s 5200 with 35c. It has two cycles.


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