New Max8 caught on fire today…

[Lil Dylan]

My 3 month old max8 gen 2 just caught on fire today and scared the poop out of me. When the hell did RC cars become so dangerous? Lippos blowing up on the internet. People's ESCs catching fire. The thing caught on fire 2 ft from my kid but didn't hurt him.
The motor stopped working yesterday so I thought maybe the recalibration screwed up. Recalibrated the throttle and motor was barely moving and just poof; caught fire in my room. If you ever see the esc lights start to go crazy back off.

Anybody know why this happens?

 

[RCbuzz]

Oh no .. I think another user reported fire with the Max8.. I sure hope this was a fluke, please let us know how Hobbywing responds.

The problem with FET's is if they short the LIPO has such a high current capability it is bound to end badly.

Edit, here was that thread: https://www.arrmaforum.com/threads/...-replacement-reported-in-amazon-review.57561/

 

[RCbuzz]

What gearing were you running? Looks like an 18tooth pinion (doesn't seem too crazy) and below it is a huge pinion sitting there?

 

[Lil Dylan]

What gearing were you running? Looks like an 18tooth pinion (doesn't seem too crazy) and below it is a huge pinion sitting there?

It's a 16t. The other pinion was from my son putting an extra pinion there. He likes to pretend to work on the car by putting spare parts all around. The car hasn't been abused or overheated. He mostly drives it at 7% WOT and that's how it was driven last before it blew up. I mainly drive the talion lately.

 

[RedOctobyr]

First off, I'm sorry to hear about the fire, and I'm glad no one was hurt!

I am not an electrical engineer, and this is based on helicopter ESC discussions from like 10 years ago. But I remember people suggesting that you didn't want your throttle percentage to be too-low, because especially if the ESC didn't do freewheeling (?), the large amount of switching the current on & off (by the ESC) could make the ESC run hotter.

Like, you wanted your motor selection, cell count, and gearing, to put you around, say, 70% throttle, for your selected headspeed, on the helicopter. But that's better than like 30% throttle. I only mention this if you're running extremely-low throttle, like 7%, I wonder if it's possible for that to produce some sort of unexpected consequence, like actually making some portion of the ESC run hotter than we might anticipate.

I don't mean to imply anything along the lines of "victim blaming"! And I'm not an EE. It just seemed like maybe this is worth adding to the discussion. Could you maybe use lower cell-count LiPos, for instance, to allow using more throttle % while your son is playing? Hopefully others can chime in on this. If I'm mis-remembering, or if this is no longer a concern, I'm happy to learn! And hopefully Hobbywing can provide some insight.

 

[Lil Dylan]

First off, I'm sorry to hear about the fire, and I'm glad no one was hurt!

I am not an electrical engineer, and this is based on helicopter ESC discussions from like 10 years ago. But I remember people suggesting that you didn't want your throttle percentage to be too-low, because especially if the ESC didn't do freewheeling (?), the large amount of switching the current on & off (by the ESC) could make the ESC run hotter.

Like, you wanted your motor selection, cell count, and gearing, to put you around, say, 70% throttle, for your selected headspeed, on the helicopter. But that's better than like 30% throttle. I only mention this if you're running extremely-low throttle, like 7%, I wonder if it's possible for that to produce some sort of unexpected consequence, like actually making some portion of the ESC run hotter than we might anticipate.

I don't mean to imply anything along the lines of "victim blaming"! And I'm not an EE. It just seemed like maybe this is worth adding to the discussion. Could you maybe use lower cell-count LiPos, for instance, to allow using more throttle % while your son is playing? Hopefully others can chime in on this. If I'm mis-remembering, or if this is no longer a concern, I'm happy to learn! And hopefully Hobbywing can provide some insight.

These are good pints and definitely something to think about. However, I don't know if I would buy that the low WOT could be the culprit. When he drives the car he drives it about 15-20 ft then goes and runs to look at it and pretend he's wrenching on it etc. Therefore, a lot of the time it's just sitting there idle with the fan running. Also, I looked through my data logs via the hobbywing app and there wasn't a single event over the last few months where the esc temps got "hot". Highest temp was 131. I know for sure that not all the logs are getting captured because the last 5 logs were of the Talion and that's not correct. So, it's possible on this specific day he overheated the esc and I have no way to disprove that. I've only owned the cars since December so all the bashing we've done has been in the winter and on this day it was 45 degrees. Just hard to believe it overheated.

In the future I will get him a smaller 2s battery and let him run it. I never thought of that so thanks.

 

[RedOctobyr]

Cool, then like you said, overheating seems like it would be unlikely. Sorry, it was just something that came to mind. I'm glad it wasn't worse, at least!

 

[Lil Dylan]

Cool, then like you said, overheating seems like it would be unlikely. Sorry, it was just something that came to mind. I'm glad it wasn't worse, at least!

It's all good. Thanks for the suggestions. I'll report back on what Hobbywing says.

 

[kspitters]

Super sorry about the fire, awesome what you’re doing for your kid.