Granite Lipo 2S Burning out Mega 550 12T Brushed Motor?

[wcndave]

My son has the Arrma granite 4x4 brushed.

Stock NiMH runs out quite quickly, so we got 2 spektrum 5000 2S LiPos.
He ran it for too long I think on first day, (as he now has 13,300 mAh instead of 3,300...) and there was a definite smell.

However it kept on running after that, and I explained that he needs to do 15 min stints, then leave to cool for 15 mins. (The temperature here is currently about -10c, yes, that's 10 below freezing)

On day 3, he ran for 15 mins, then had 20 minute break, then ran again, and after 10 mins it came to a slow stop, and won't start again.

Putting a meter on the battery terminals reveals there is 8v across it, so I can only think that the motor is gone - although I would have expected a more sudden death, or when it was overused the first time...



So, needs a new motor, and I have seen some people suggesting a better brushed motor to avoid the heat.
Then I have seen some threads on LiPo 2s just burning out motor after motor. (although they are officially supported with stock motor)
I looked at brushless, however it looks like that means new ESC, and then bearings, and gears, and diffs, and nubs and nibs and nobs that I don't understand - this is my son's thing not mine!



So - my questions are:

Can I replace the motor with the same one, and just make sure it's not run for more than 15 mins at a time - and assume that first long run was what did it?
Can I replace the motor with a better brushed one that will stand up to the LiPo?
Can I replace with some brushless combo that won't stress it more than the current setup, hence no need to go replacing all the parts, or risking them breaking?

We have temperatures from -15C up to 40C to content with.

Many thanks in advance!

Dave

 

[RCBro80]

Sounds like the motor is toast, yes it can get quite hot... taking break between packs is definitely advisable. To be sure, did you check the voltage on the motor leads when you give it throttle? I'm not 100% sure whether this will work if the motor windings have failed open, but can't hurt to check.

If this is the V3 Granite (2020 release date), I would strongly recommend considering an upgrade to brushless (motor & ESC) which will handle the heat on 2S much better and be more future-proof for your son (because you'll be able to run on 3S as well). The V3 includes the upgraded drivetrain to make the brushless upgrade much easier and more affordable. Here is the motor and ESC that I've purchased to upgrade my son's Granite:

this motor (3300kv): https://www.banggood.com/Racerstar-...html?cur_warehouse=USA&rmmds=search&ID=511868

and this ESC: https://www.aliexpress.com/item/1005001329236932.html?spm=a2g0s.9042311.0.0.26dc4c4d5NUQ9y

Also consider www.jennysrc.com for reasonably priced components.

 

[wcndave]

Sounds like the motor is toast, yes it can get quite hot... taking break between packs is definitely advisable. To be sure, did you check the voltage on the motor leads when you give it throttle? I'm not 100% sure whether this will work if the motor windings have failed open, but can't hurt to check.

If this is the V3 Granite (2020 release date), I would strongly recommend considering an upgrade to brushless (motor & ESC) which will handle the heat on 2S much better and be more future-proof for your son (because you'll be able to run on 3S as well). The V3 includes the upgraded drivetrain to make the brushless upgrade much easier and more affordable. Here is the motor and ESC that I've purchased to upgrade my son's Granite:

this motor (3300kv): https://www.banggood.com/Racerstar-...html?cur_warehouse=USA&rmmds=search&ID=511868

and this ESC: https://www.aliexpress.com/item/1005001329236932.html?spm=a2g0s.9042311.0.0.26dc4c4d5NUQ9y

Also consider www.jennysrc.com for reasonably priced components.

Regarding voltage, yes, I get 0v when throttle closed, and 8v when open. So it seems the ESC is delivering the volts.

Re: V3, so are you saying that the V3 (which I have), already includes some upgraded parts so you _only_ need to get the motor/esc?

Re: Jenny, I am in Italy, so need to find mainland continent sellers - I can see that in US this is much easier!

Thanks

 

[RCBro80]

Re: V3, so are you saying that the V3 (which I have), already includes some upgraded parts so you _only_ need to get the motor/esc?

Yes, that's my understanding. You can compare the exploded drawings to be sure

 

[wcndave]

So I managed to get a new motor. Installed it. Everything is set to off. Plug the battery in.

Without doing anything, the ESC started smoking, smelling, and we unplugged it.

Is it possible that the ESC was burned up by too long running?
Can a bad ESC have killed the motor?

What is odd, is that before changing the motor this didn't happen, perhaps the old motor wasn't drawing any current, and the new one did?

Any thoughts before I splash out for a new ESC, just a few weeks after purchase!

 

[RCBro80]

You can always contact Horizon Hobby and request a warranty replacement, rather than buying a replacement.

My sons and I have driven the mega pretty hard and never burned it out (however one of my boys did burn up a Redcat Volcano motor when he buried it in a pile of mulch and held the throttle for too long). Use your gut, but this sounds like a valid warranty claim.

Can a bad ESC kill a motor? Maybe, although I suspect it was just heat that killed the motor. Did that motor kill the ESC or was it the heat? Who's to say.

I'm realizing that my response isn't very helpful... bottom line is heat is your enemy. If you do end up replacing everything, I'll say again that brushless may be the way to go. A properly spec'd brushless motor & ESC with proper gearing will be much more robust than a brushed setup.

 

[wcndave]

Thanks. He got the brushed one, because we weren't willing to allow him to spend so much on an Xmas present...

The problem with the warranty idea, is that it was purchased through a retailer here in Italy, so I probably have to go through them.
That is likely to be a real pain, especially as I don't speak Italian (here in my part German is the main language).

I will see if I can communicate with them - however it's almost certainly going to be less hassle to just get a replacement somewhere...

Thanks again.

 

[RCBro80]

All warranties are handled by Horizon Hobby directly. If you have the bill of sale, you can email them [email protected] or call

 

[joshual1177]

Sounds like the motor is toast, yes it can get quite hot... taking break between packs is definitely advisable. To be sure, did you check the voltage on the motor leads when you give it throttle? I'm not 100% sure whether this will work if the motor windings have failed open, but can't hurt to check.

If this is the V3 Granite (2020 release date), I would strongly recommend considering an upgrade to brushless (motor & ESC) which will handle the heat on 2S much better and be more future-proof for your son (because you'll be able to run on 3S as well). The V3 includes the upgraded drivetrain to make the brushless upgrade much easier and more affordable. Here is the motor and ESC that I've purchased to upgrade my son's Granite:

this motor (3300kv): https://www.banggood.com/Racerstar-...html?cur_warehouse=USA&rmmds=search&ID=511868

and this ESC: https://www.aliexpress.com/item/1005001329236932.html?spm=a2g0s.9042311.0.0.26dc4c4d5NUQ9y

Also consider www.jennysrc.com for reasonably priced components.

This is the same esc I bought for mine. It’s coming in the mail tomorrow. We’ll see how well it works.

 

[Sparky32]

How well does the upgrade work? Is it just a case of swapping esc and motor?.thinking of buying 2s but impact on stock motor worries me so thinking to get esc and motor in hand reasy to replace

 

[RCBro80]

My son runs the granite on 2S - no issues thus far, but the motor gets hot so I'm sure under the right conditions a failure is entirely possible.

If you have a 3rd gen (2020) Mega, the power module (motor mount & slipper assembly) have to be replaced and the aluminum wheel hexes are a good idea (and cheap enough) before upgrading to a brushless system. If you have an older Mega, the diffs and input gears also need to be replaced.

 

[joshual1177]

As long as you don’t overheat the brushed motor, 2s should be fine. That means not throwing in a battery immediately after the first one goes dead but giving the motor time to cool off. But don’t expect it to last nearly as long as a brushless setup. But, brushed motors are a fraction of the price but will add up quickly if you keep burning them up. The extra power will also overheat the esc. Which means it will keep shutting off and eventually stop working altogether. A brushless upgrade is really easy to do. Which is what I would recommend down the road.

 

[wcndave]

Hi, contacted support by email twice, no reply, tried the phone, but was "out of office hours" whenever I tried.
Just ordered the part from local hobby store instead, so ready to go.

When then one burns out - will try the upgrade, however if the brushed is really so bad that it doesn't last a week, perhaps it ought to not be sold...

We went for this model, as allowing a 13year old a €500 xmas present is just too much (we normally have a limit of 100), however this is going to end up costing quite a bit more by the end....

Thanks for all the help folks!

 

[GraniteFox]

Never had much luck with the brushed motors and esc units. They do require a good cleaning every 5-10 runs. Best bet is to go with a modest brushless system to run on 2s. There are some low cost options from hobbywing that are good units. This would be considered a low cost option and the shaft size is the same as the brushed motor so it would be a complete drop in. https://www.hobbywingdirect.com/products/ezrun-max10-combo

 

[Infantryman117]

I had the V3 granite mega and the motor started going bad after a few uses with the spektrum 2s lipos. I decided to return the truck and get the arrma big rock, by far the better decision than to try and replace the motor. I only run the big rock on the. 2s lipos and it is way faster and much more fun. You could also go with the granite blx(same price). I think you will end up spending less in the long run and have a better truck that makes you happy.

 

[FlipSide]

I went down the same road last year. After 4 burned motors on my son's Granite Mega V2 within a few months, I purchased a new Granite 3S V3.

It's kind of a catch 22 situation. Arrma has to offer such affordable cars because of the demand, but the performances and reliability are so poor that it nearly always end up with frustrated customers. It's a shame because the 3S version is amazing.

Südtirol is one of my favorite area of the world. I went there a couple of times and I can't wait to get back there...eventually!

 

[L3phturn]

How well does the upgrade work? Is it just a case of swapping esc and motor?.thinking of buying 2s but impact on stock motor worries me so thinking to get esc and motor in hand reasy to replace

Yes, on the V3 Mega trucks Arrma makes almost all of the drivetrain the same. On 2S you can simply put the Spektrum firms (or equivalent) brushless ESC and motor in place of the originals and it will work fine. If you want to run on 3S you may want the upgraded slipper clutch.

What terrain are you running on and what sizes pinion is on the truck now? The vast majority of motor failures are due to overheating, and a smaller pinion will help a great deal.

 

[HoleyDonut]

I bought a V3 Granite Mega and we've had it for only a week. On a single charge, it'll run for only 15 minutes...which is probably a good thing because the motor runs so hot. Unfortunately, after four runs (ie, about an hour of running) the first motor burned itself out. The second motor burned itself out after another three runs.
We went back to the store and asked what was going on. We never run our unit at anything over 50%, primarily due to the fact that our 8 year old kid likes to run after it as he's playing with it. Even at this, supposed, lowest setting, it still kills motors resulting in far more downtime and greatly increase operating costs. Store gave us our latest motor (this one will be the third) and advised to reach out/contact Horizon directly. Everything is stock on the unit. Nothing has been modified because we don't know anything about that. It took us two hours to change out the motor when it burned out the first time.
After contacting Horizon and explaining our situation, the representative came to the conclusion that we might need a new ESC (electronic speed controller - whatever that is) and a new motor. We will wait to see if that solves anything...but that toy is just sitting now. Less than 2hrs of actual run time.

 

[GraniteFox]

If your running in grass it may be putting too much stress on the motor and esc. None of them like running in grass Including the 3sBLX and 6s line. very short grass, dirt, and pavement are best. If you are running in medium grass you will need to go smaller on the pinion.

 

[joshual1177]

I bought a V3 Granite Mega and we've had it for only a week. On a single charge, it'll run for only 15 minutes...which is probably a good thing because the motor runs so hot. Unfortunately, after four runs (ie, about an hour of running) the first motor burned itself out. The second motor burned itself out after another three runs.
We went back to the store and asked what was going on. We never run our unit at anything over 50%, primarily due to the fact that our 8 year old kid likes to run after it as he's playing with it. Even at this, supposed, lowest setting, it still kills motors resulting in far more downtime and greatly increase operating costs. Store gave us our latest motor (this one will be the third) and advised to reach out/contact Horizon directly. Everything is stock on the unit. Nothing has been modified because we don't know anything about that. It took us two hours to change out the motor when it burned out the first time.
After contacting Horizon and explaining our situation, the representative came to the conclusion that we might need a new ESC (electronic speed controller - whatever that is) and a new motor. We will wait to see if that solves anything...but that toy is just sitting now. Less than 2hrs of actual run time.

You can get a brushless motor and ESC for less than $100 that with last a much longer time than the stock brushed motor and esc.