Am I Wrong Thinking A Higher Amp ESC Will Solve My Issue?

[bigbristv]

I have a Senton Mega converted to a BLX and first went with a 3650 3900kv motor with a 60a esc combo which I still have but later put in a road car.

So I went up to a 3660 4200kv motor with an 80a esc.

I was having very little to no issues with the first combo but I couldn't wheelie or hit 50mph.

The second combo stripped the mega pinion and rear diff so I switched up to the BLX setup for those items which changed gearing.

So now I was having more frequent thermal limp mode sessions so I decided to get a 120a esc. Burned it up, like desoldered batt connectors, purple smoke and all.

Replaced it with the same esc and I'm thinking it's going thermal (blinking light) but it hasn't measured over 100 degrees after a run and while blinking.

This led me to look at the mfg stated parameters for their escs and found between the 60a, 80a, 120a, 150a, each one recommends less than 4000kv, 3000kv, 2000kv etc. respectively.

I have a 3500kv motor coming tomorrow and was going to order a different brand 120a esc but should I just stick with the 60a? The recommended kv is around 3500-4000 for that one.

Sorry for the long read but I just want to run on 3s (5200mah 80c) and be able to wheelie on demand and run hard without having to keep waiting for the thermal shutdown to subside.

What do I do?

 

[BarnFabRC]

Could it be that you’re hitting a voltage cut and not a thermal cut?

 

[Greywolf74]

I have a Senton Mega converted to a BLX and first went with a 3650 3900kv motor with a 60a esc combo which I still have but later put in a road car.

So I went up to a 3660 4200kv motor with an 80a esc.

I was having very little to no issues with the first combo but I couldn't wheelie or hit 50mph.

The second combo stripped the mega pinion and rear diff so I switched up to the BLX setup for those items which changed gearing.

So now I was having more frequent thermal limp mode sessions so I decided to get a 120a esc. Burned it up, like desoldered batt connectors, purple smoke and all.

Replaced it with the same esc and I'm thinking it's going thermal (blinking light) but it hasn't measured over 100 degrees after a run and while blinking.

This led me to look at the mfg stated parameters for their escs and found between the 60a, 80a, 120a, 150a, each one recommends less than 4000kv, 3000kv, 2000kv etc. respectively.

I have a 3500kv motor coming tomorrow and was going to order a different brand 120a esc but should I just stick with the 60a? The recommended kv is around 3500-4000 for that one.

Sorry for the long read but I just want to run on 3s (5200mah 80c) and be able to wheelie on demand and run hard without having to keep waiting for the thermal shutdown to subside.

What do I do?

We need more info. What brand ESCs (80A & 120A) and motor are they? You said you switched to the BLX set up, Does that mean they are Spektrum brand or did you just meant you went brushless with it like the BLX rigs? Were the ESC and motor brand new or used? What was the original 60A ESC you were using? What gearing are you using? What is the stock gearing? Do you have oversized tires on it? Have you changed any of the stock ESC settings when you switched?

A 120A ESC of any decent brand should not be hitting thermals with a 550 can motor on it. There would have to be other forces at play for that to happen. The first thing that pop to mind is gearing or something related to gearing. The second would be if you had some sort of restriction in your driveline somewhere like seized or partially seized bearings in a transmission or a diff, that sort of thing.

The gearing thing sticks out to me because you said the gearing changed. if you changed the gearing and went with a much higher gear ratio (say 2:1 rather than 4:1) than the original set up then this could potentially cause a 120A ESC to meltdown.

Also that BarnRC asked about being sure it was a thermal error code as opposed to some other error code is a valid question too because no ESC should be hitting thermal throttle if the ESC is only hitting 100F.

Last but not least, The fact that your running 200Kv higher than recommended specs in and of itself probably isnt a significant issue but if coupled with improper gearing could be lending to the problem you're experiencing.

 

[bigbristv]

We need more info. What brand ESCs (80A & 120A) and motor are they? You said you switched to the BLX set up, Does that mean they are Spektrum brand or did you just meant you went brushless with it like the BLX rigs? Were the ESC and motor brand new or used? What was the original 60A ESC you were using? What gearing are you using? What is the stock gearing? Do you have oversized tires on it? Have you changed any of the stock ESC settings when you switched?

A 120A ESC of any decent brand should not be hitting thermals with a 550 can motor on it. There would have to be other forces at play for that to happen. The first thing that pop to mind is gearing or something related to gearing. The second would be if you had some sort of restriction in your driveline somewhere like seized or partially seized bearings in a transmission or a diff, that sort of thing.

The gearing thing sticks out to me because you said the gearing changed. if you changed the gearing and went with a much higher gear ratio (say 2:1 rather than 4:1) than the original set up then this could potentially cause a 120A ESC to meltdown.

Also that BarnRC asked about being sure it was a thermal error code as opposed to some other error code is a valid question too because no ESC should be hitting thermal throttle if the ESC is only hitting 100F.

Last but not least, The fact that your running 200Kv higher than recommended specs in and of itself probably isnt a significant issue but if coupled with improper gearing could be lending to the problem you're experiencing.

See, this is why I went ahead and posted this here, these are the kinds of questions that let me know I came to the right place.

Ok, so the driveline is not restricted, the rig is free rolling, etc. The "BLX" upgrade consists of everything from those models sans [Spektrum] electronics.

I measured temps at the battery leads directly where they exit the esc with a touch (meat) thermometer.

Gearing is the stock BLX gearing so the switch was essentially going from 91t spur x 17, then 23t pinion (ran fine on 3s with 60a esc, a little better with 80a esc) to 57t spur x 20t pinion (cogs bad on startup w/ 60a esc even with punch set to max, and a bit w/80a esc whose fan was intermittent so I think that's why it would go thermal). Those escs were the Gool/Surpass ones.

The third esc, 120a looked different but still one of those El cheapo ones and the first burned up after a few days of hard driving. Was not programmed (by me). I say that because the replacement I received needed to be programmed (reset) in order to work. I increased LVC threshold after it went limp mode which is why I assume thermal, plus the rapid blinking light.

I just woke up and thinking about the recs from the mfr I think what might be happening is they assume that if I want a higher amp esc I must want to run higher voltage with a bigger motor and lower kv.

Where I become a Dummy (or where these "cheap" electronics fails come into place) from that perspective is me wanting to run a [relatively] high kv motor in an inappropriately sized motor.

I came across a guy doing research on this (I think his name is Ryan) that on his channel goes full geek squad with the math and explains it excellently, the conclusion being these companies just recommend a motor/esc/servo etc. based on your intended application in lieu of having you have to do calcs.

I like the strength of the Gool/Surpass fans and performance so I'm going to try one of their 120a esc to see if this works. If not I will cave and get something from a more "reputable" brand.

 

[WickedFog]

So you went from a 5.35:1 to a 2.85:1 gear ratio. That is a huge difference that will generate a lot more heat in your motor and ESC.

You will want to take the ESC temp with an infrared temp gun, and aim it at the main body of the ESC. That is were the heat generating components of the ESC are located. The temps will be cooler at the solder contacts for the battery/motor, unless you have a bad solder joint there and are getting a bottleneck in the current right there. Generally, if you can't put your finger on top of the ESC and hold it there, you're too hot. But get a temp gun off Amazon. They are cheap.

Another possibility - I've owned a couple GoolRC ESC's and they were pure garbage. Buy a Hobbywing or Castle ESC. Just sayin.

 

[bigbristv]

So you went from a 5.35:1 to a 2.85:1 gear ratio. That is a huge difference that will generate a lot more heat in your motor and ESC.

You will want to take the ESC temp with an infrared temp gun, and aim it at the main body of the ESC. That is were the heat generating components of the ESC are located. The temps will be cooler at the solder contacts for the battery/motor, unless you have a bad solder joint there and are getting a bottleneck in the current right there. Generally, if you can't put your finger on top of the ESC and hold it there, you're too hot. But get a temp gun off Amazon. They are cheap.

Another possibility - I've owned a couple GoolRC ESC's and they were pure garbage. Buy a Hobbywing or Castle ESC. Just sayin.

Yeah, just went up for a quick run and it worked well for a few minutes (saw all of 11mph, short bursts with wheelies) then dead for 3 minutes. Flashing light and temp 91 deg. Motor not hot at all. Turned the LVC off to rule that out.

I measured at the leads because those desoldered on the other (same type/brand) esc that melted.

Gonna chalk this up to crap, try another 120a and then go unbranded from there if needed and report back.

Thanks for your help.

 

[WickedFog]

Yeah, just went up for a quick run and it worked well for a few minutes (saw all of 11mph, short bursts with wheelies) then dead for 3 minutes. Flashing light and temp 91 deg. Motor not hot at all. Turned the LVC off to rule that out.

I measured at the leads because those desoldered on the other (same type/brand) esc that melted.

My guess is your ESC overheated and went up in smoke due to the crazy gear ratio you are running. It likely got so hot it desoldered the cables.

Again, it was likely hotter at the main body of the ESC, unless you had bad solder connections causing heat to build in the wires.

And again... get a temp gun and check your temps correctly. ESC, motor, and battery. Or you can just keep buying a new ESC every time you want to run it

 

[bigbristv]

My guess is your ESC overheated and went up in smoke due to the crazy gear ratio you are running. It likely got so hot it desoldered the cables.

Again, it was likely hotter at the main body of the ESC, unless you had bad solder connections causing heat to build in the wires.

And again... get a temp gun and check your temps correctly. ESC, motor, and battery. Or you can just keep buying a new ESC every time you want to run it

The gear ratio I'm running is the stock BLX stuff so I wouldn't call it crazy. Also, I do run an alarm on my batteries. Stock BLX runs 100a esc x 3200kv 3660 motor BTW. Maybe the Spektrum electronics are better than the Gool stuff.

And I know for a fact it isn't getting hot enough to cause thermal issues, maybe the wires on the one I smoked had a soldering issue because it should have done the whole thermal cutoff like it's replacement is doing now, just too soon.

Anyway, if the 120a Gool (I find those fans run much stronger than the current type I have now) I'm about to order works well with the 4200kv and 3500kv motors, good.

If not I'll try the HW MAX10 SC and see how that does.

 

[WickedFog]

What all is different from the Mega to the BLX besides the pinion and spur? There are other things that determine the final drive ratio. Are the tires the same diameter from the Mega to the BLX? Are the differential ring and pinion gears the same?

 

[ahr43]

bigbris, what is the battery pack voltage at the end of one of these ESC burn-downs and solder melt sessions?

That will be a good indicator of the load the system is under. 'AC'

 

[Greywolf74]

The gear ratio I'm running is the stock BLX stuff so I wouldn't call it crazy. Also, I do run an alarm on my batteries. Stock BLX runs 100a esc x 3200kv 3660 motor BTW. Maybe the Spektrum electronics are better than the Gool stuff.

And I know for a fact it isn't getting hot enough to cause thermal issues, maybe the wires on the one I smoked had a soldering issue because it should have done the whole thermal cutoff like it's replacement is doing now, just too soon.

Anyway, if the 120a Gool (I find those fans run much stronger than the current type I have now) I'm about to order works well with the 4200kv and 3500kv motors, good.

If not I'll try the HW MAX10 SC and see how that does.

WF is correct. First thing you need to do is get an IR temp gun and every minute or two pull the RC up to you and check the temp at the main body of the ESC below the cooling fins on the top and while you're at it check your motor temps too. ESC really shouldnt go over 150-160F-ish and the motor shouldnt go over 170F.

Second thing Id do it look up what the flashing LED error code on the ESC actually means.

Lastly, if it really is going in to thermal shutdown then you need to increase the size of the spur and/or decrease the size of the pinion. I can see that gearing on a 4200Kv motor running 3S being a problem.

Also you appear to be contradicting yourself because you make the statement "And I know for a fact it isn't getting hot enough to cause thermal issues" but you also repeatedly stated that the ESC is going in to thermal shutdown. If its not overheating it wouldnt be going in to thermal shutdown.

bigbris, what is the battery pack voltage at the end of one of these ESC burn-downs and solder melt sessions?

That will be a good indicator of the load the system is under. 'AC'

He wouldnt know sicne he doesn't have a proper IR temp gun.

 

[WickedFog]

If you wanna go cheap on the electronics, go to jennysrc.com and just grab the BLX system from the Senton. Kind of late to be asking this, but do you have the 2wd or 4wd Senton?

 

[bigbristv]

What all is different from the Mega to the BLX besides the pinion and spur? There are other things that determine the final drive ratio. Are the tires the same diameter from the Mega to the BLX? Are the differential ring and pinion gears the same?

I'm sorry, I assumed all knew the differences between the models- I also posted this on the Arrma forum.

The Only essential difference between the MEGA & BLX models is the former runs 48p 0.8 mod gearing (spur & pinion) and the latter 32. Stock Mega runs 91t spur with a 17t pinion on a brushed system. BLX runs 57t spur with a 20t pinion on a brushless system.

At first when I converted from brushed to brushless I kept the higher gearing and when I shredded it, moved to the stock BLX gearing.

bigbris, what is the battery pack voltage at the end of one of these ESC burn-downs and solder melt sessions?

That will be a good indicator of the load the system is under. 'AC'

The voltage at the end of the runs is about the same as it has always been after a run, nominal decrease as per the checker. Thanks AC!

WF is correct. First thing you need to do is get an IR temp gun and every minute or two pull the RC up to you and check the temp at the main body of the ESC below the cooling fins on the top and while you're at it check your motor temps too. ESC really shouldnt go over 150-160F-ish and the motor shouldnt go over 170F.

Second thing Id do it look up what the flashing LED error code on the ESC actually means.

Lastly, if it really is going in to thermal shutdown then you need to increase the size of the spur and/or decrease the size of the pinion. I can see that gearing on a 4200Kv motor running 3S being a problem.

Also you appear to be contradicting yourself because you make the statement "And I know for a fact it isn't getting hot enough to cause thermal issues" but you also repeatedly stated that the ESC is going in to thermal shutdown. If its not overheating it wouldnt be going in to thermal shutdown.


He wouldnt know sicne he doesn't have a proper IR temp gun.

I don't think it going to invest in a temp gun, thanks. What I'm seeing is not normal and apparently can be chalked up to bad electronics which is why I'm going up a notch after all of this. This way I'll be able to get telemetry moreso than what the cheap stuff provides.

When I stated the thermal stuff, it was because that's the way that particular esc behaves in that situation and I have ruled out the low voltage theory. Plus it's late brother melted and desoldered the batt wires.

If you wanna go cheap on the electronics, go to jennysrc.com and just grab the BLX system from the Senton. Kind of late to be asking this, but do you have the 2wd or 4wd Senton?

It's the 4x4 and Jenny's was an option but I wanted a bit more than stock. Going HW now.

It may sound silly since I soldered tiny wires to add LED lights to both of my BLX bodies but I did all of this because I didn't want to move away from the deans connectors my batteries have.

Oh well, learning experience at its best

 

[WickedFog]

You NEED a temp gun in this hobby. They are like $9 and up on Amazon.

 

[DavidB1126]

Got my temp gun from harbor freight, 15 bucks. Nice durable one. I use it every time after a session or race on the track.
https://www.harborfreight.com/121-infrared-laser-thermometer-63985.html
24 bucks now tho
I like to keep my motors below 180 ish. ESCs under 120.

 

[Grizz03]

FWIW: Deans connectors are only rated at 60amps.
I've seen many similar issues from undersized wires, connectors and bad solder joints.

 

[bigbristv]

FWIW: Deans connectors are only rated at 60amps.
I've seen many similar issues from undersized wires, connectors and bad solder joints.

That's what I was afraid of, doing a bad soldering job on higher level electronics.

I've just done the calculations and I had $212.79 in 2 different cheap esc motor combos and their respective programming cards. Didn't realize how quickly it adds up especially when your piecing things together.

Decided to go with the HOBBYWING Quicrun 10BL120 G2 & 3660SL G2 Combo (QR10BL120 + 3660-3700KV SL G2 Combo) Gen2 for $85. Add a program card for $10, 5mm pinion set for $15 and I should be good to go for half of the initial layout.

Looking at it this way; at least now I know first hand to stay away from the cheap stuff, especially electronics. And to get a heat gun

And I got the experience of learning my first Arrma rig and got in the wrench time. All plusses from when I stand.

 

[WickedFog]

All that should get you going. I would suggest you go small on the pinion until you get the temp checked. It doesn't take long to fry something when electronics overheat. No time at all.

 

[bigbristv]

All that should get you going. I would suggest you go small on the pinion until you get the temp checked. It doesn't take long to fry something when electronics overheat. No time at all.

Yest this is why I'm ordering a set of pinions of differing sizes, up to 20t which I currently run. Thanks!

 

[Greywolf74]

FWIW: Deans connectors are only rated at 60amps.
I've seen many similar issues from undersized wires, connectors and bad solder joints.

FWIW: That is not true of Genuine Deans connectors.