Brand new Mamba Micro X caught on fire after 5 minutes.

[Ace.]

Hey guys, just got finished buttoning up a build this morning, and within 5 minutes the things on fire. :lmao:

Specs are:
Mamba Micro X esc (supposedly crawler edition :?: Brand new from AMain hobbies)
Castle 10amp Bec (brand new)
Holmes Hobbies Revolver V2 Snubnose 2500kv. (Brand new)
ProTek Graphene Plus LiHV 4500mah 3s 120c battery.
I was just testing the crawling speed on my concrete basement floor luckily.

This is actually the second Micro X I've had burn up connected to a revolver motor, the first was an 1800kv and I just threw everything away and chalked it up to buying used :roll:

This ever happen to anyone else? I'm trying to make this build as light as I can, right now with battery my weight is 4lbs 13.6oz.

Any insight would be welcome thanks!!!

 

[Topher Builds]

Man that’s roughl! Sorry to hear it.

The micro x in my Sherpa barely gets warm, which is a heavier rig with a revolver. I run it with lihv batteries as well.

For it to go up that quick I’d think there has to be something else going on here. No idea what that is though. Battery connector soldering clean? What rig and what are you geared at?

 

[TheLetterJ]

What's your final drive ratio and tire height? I ran a MicroX in an 8lb+ car with a standard size 1800kv Revolver on 3s with 6" tall tires for a year or so without issue. The key being that it was geared 65:1 so it didn't have to work too hard. It's now in a 6.5lb car with 5.75" tires and a 2700kv Puller Pro Stubby and runs significantly warmer than the previous setup, but the fdr is taller at ~48:1.

Did it take out your servo or receiver too? What voltage is your bec at, and did you remove the positive wire from the esc's rx connector? Just trying to brainstorm other possibilities like backfeeding too much voltage from the bec to the rx on top of the internal bec's voltage might have done some damage? Totally just spitballing ideas.

 

[Ace.]

Man that’s roughl! Sorry to hear it.

The micro x in my Sherpa barely gets warm, which is a heavier rig with a revolver. I run it with lihv batteries as well.

For it to go up that quick I’d think there has to be something else going on here. No idea what that is though. Battery connector soldering clean? What rig and what are you geared at?

Yes battery connection clean, axial capra with ax10/scx10 3 gear transmission, 9t pinion, I believe 57t spur (I'll have to open the case and look I know I went bigger just can't remember) I literally gutted everything from the cage, it's naked right now, everything else is stock axle gearing, the RTR Spektrum servo, I have a savox 2230 sitting here waiting, just wanted to get it tested.

 

[Ace.]

What's your final drive ratio and tire height? I ran a MicroX in an 8lb+ car with a standard size 1800kv Revolver on 3s with 6" tall tires for a year or so without issue. The key being that it was geared 65:1 so it didn't have to work too hard. It's now in a 6.5lb car with 5.75" tires and a 2700kv Puller Pro Stubby and runs significantly warmer than the previous setup, but the fdr is taller at ~48:1.

Did it take out your servo or receiver too? What voltage is your bec at, and did you remove the positive wire from the esc's rx connector? Just trying to brainstorm other possibilities like backfeeding too much voltage from the bec to the rx on top of the internal bec's voltage might have done some damage? Totally just spitballing ideas.

Not sure on final drive ratio, it's an ax10/scx10 3 gear trans, 9t/57t (I think it's 57t, gotta look again) capra stock axle gearing, tires are sitting at 5.25" right now, rc4wd bully comps.

I don't know if it took anything else out yet, I haven't gotten the chance to dig into it, positive wire was pulled from esc connection and I put a piece of shrink tube over it. Bec was at 7.4. thanks for the brainstorming lol, this is my first brushless setup, so I'm still learning.

 

[TheLetterJ]

Well you're definitely geared low enough, that comes out to 118.56:1! That said, were you running at/near full throttle when she blew? Your esc basically thinks that 2500kv 14pole is the same as an 8750kv 4pole, maybe the rapid switching just generated too much heat?

My MambaX (standard, not micro) happily runs the 1800kv on 4s, but shuts down if I give it much over 1/2 throttle on 6s. I'm no good at explaining it, but it doesn't have so much to do with the voltage as it does the amount of electrical pulses it's capable of sending in a given time... 2500kv x 14 poles x 11.1v might just be beyond the "turn" limit of the micro x?

 

[Ace.]

Well you're definitely geared low enough, that comes out to 118.56:1! That said, were you running at/near full throttle when she blew? Your esc basically thinks that 2500kv 14pole is the same as an 8750kv 4pole, maybe the rapid switching just generated too much heat?

My MambaX (standard, not micro) happily runs the 1800kv on 4s, but shuts down if I give it much over 1/2 throttle on 6s. I'm no good at explaining it, but it doesn't have so much to do with the voltage as it does the amount of electrical pulses it's capable of sending in a given time... 2500kv x 14 poles x 11.1v might just be beyond the "turn" limit of the micro x?

That makes complete sense, should I volt down to the 1800k I have sitting here with a spare brand new micro x, and buy the Mamba x or sidewinder 4 for the 2500?

Thanks again for the help!!

 

[TheLetterJ]

I know from experience that the micro x will run a 14 pole, 1800kv Revolver on 3s. I did find some more of the terms I was searching for, each ESC has an "electrical rpm" limit, you can find your setup's e-rpm by multiplying kv by pairs of poles (4 pole has 2 pairs, 14 pole has 7 pairs, etc) multiplied by voltage. So your 2500kv, 14 pole (7 pairs) and 3s battery 11.1 nominal/12.6v max) would have an e-rpm of 388,500/441,000. The same setup but with 1800kv would be 139,860/158,760 which is considerably lower.

The problem is that I still can't find the e-rpm limit of the Mamba X, Micro X, or SW4 to see where these setups fall. @johnrobholmes or @robert@castle might be able to chime in to help answer that?

 

[Ace.]

I know from experience that the micro x will run a 14 pole, 1800kv Revolver on 3s. I did find some more of the terms I was searching for, each ESC has an "electrical rpm" limit, you can find your setup's e-rpm by multiplying kv by pairs of poles (4 pole has 2 pairs, 14 pole has 7 pairs, etc) multiplied by voltage. So your 2500kv, 14 pole (7 pairs) and 3s battery 11.1 nominal/12.6v max) would have an e-rpm of 388,500/441,000. The same setup but with 1800kv would be 139,860/158,760 which is considerably lower.

The problem is that I still can't find the e-rpm limit of the Mamba X, Micro X, or SW4 to see where these setups fall. @johnrobholmes or @robert@castle might be able to chime in to help answer that?

I really appreciate all your help sir, I just got home from work and dug into the rig, I rigged up my spare micro x just to get power to everything, rx, servo, and motor seem to be fine, pulled transmission case off to see if anything was binding, and also look at spur gear number, it's a 57t, everything in the transmission and axles moves smooth and free (just trying to find a binding situation in the drivetrain if there was one)

 

[Cincygoon65]

I had the same setup 2500kv snubnose revolver, micro-x, on 3s. It was in an enduro, with stock gearing that weighed 4.6lbs, and it smoked the micro x on its 2nd outing. Nothing got hot, it was on a flat gravel parking lot when it happened. It had only been powered up for about 5 min. Castle replaced the esc under warranty, i sent it in and they sent out a replacement.

Sent from my SM-N960U using Tapatalk

 

[Lashlee]

Mine was in a Capra when it lost it's mind. It'll be on the way back to Castle on Monday.