Lit my sons motor on fire

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Yiggityyamz

RCNT Rookie
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17
After watching a few people messing around with these wltoys 12428 on YouTube and modding them I decided to screw around and see what the stock esc and gears could handle.
Wellll.....turns out going from a 1500mAh 2 cell LiIo to a 4000mAh 40C lipo was a bit more than I planned haha the car rode fine at first but it had so much power that it spun the drive shaft right off. Superglued that back on for a temp fix to keep us going since the hex screws that held it on snapped right out of their threads. After about 20 mins of hard/high speed bashing you could smell plastic in the air and within a minute or 2 more the car had a plume of smoke coming out. Motor was so hot I couldn't believe the mounts weren't melting the plastic undercarriage. Whoops. Good news is, battery was still at about half charge or more so these things are going to last forever vs the stock battery that gives you about 10 mins.
Wondering if the style of driving we use it for, paired with the excess power of the new battery is just too much for a brushed crawler set up. Thinking ill probably throw a nice brushless motor+esc+reciever in there but I've also seen some brushed engine upgrades that may be able to handle it.
What do you guys think, brushed or brushless for jumps, bumps and general high speed off road bashing?

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Side note, just ordered some fpv drone gear for myself! After having so much fun with his rc car I think I need an rc of every type. Man this is gonna be an expensive hobby 😅
 

Yiggityyamz

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Does that esc even have a lipo mode? Never run lipos on an esc that doesn't have one or isn't set to one :D
Lol probably not. I really just did it because I planned on upgrading everything piece by piece anyway to turn this little $50 rc into a perfect basher but i figured the esc would burn up before the engine 😂 esc seems fine and engines working currently but I know after smoke it doesn't have long. crazy fun tho. Pulls the thing into a full wheelies even in grass
 

olds97_lss

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You can get a cheap lipo alarm for $5 that plugs into the balance plug. It sets off shrieking beeps once any cell gets down to the voltage you set it at. Might be worth the $5 if you want to keep running lipo's on a non lipo esc.
 

D3MON

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i thought that those came with a small lipo pack, dont have any clue what kind of LVC (if it even does) it has though.
 

Yiggityyamz

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You can get a cheap lipo alarm for $5 that plugs into the balance plug.
this esc has a low battery cutoff but since it didn't ship with a LiPo I just picked up 2 of those little battery checker/alarms for 3 bucks including shipping haha thanks for the suggestion! I'll probably perma-mount one inside the car and have one in my battery bag to check individual cell voltages.
 

Yiggityyamz

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i thought that those came with a small lipo pack, dont have any clue what kind of LVC (if it even does) it has though.
It comes with a 1500mah 7.4v LiIo pack and a low voltage cutoff that shuts the car down and flashes all leds when the batt is drained. I'll attach of pic of the stock LiIo next to the monster lipo I modified the chassis to accept. You can still balance charge them as a 2s lipo to get correct voltage settings on most chargers but it may overcharge it slightly. Haven't seen any damage or performance issues with the pack from doing it yet. I've gone back to using the original stock pack until I can upgrade the cars components and it's still running fine even after the smoke fiasco.
I believe it handles the power of the 2s lipo just fine but that little brushed engine gets too hot to touch after just burning through the stock 1500mah pack so the 4000mah lipos just kept it running so long the engine couldn't cool fast enough to keep up. I'd try adding a heatsink but I feel like it's a moot point if I'm going to be building it into a brushless basher.
 

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HPIguy

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Without knowing the nominal individual cell voltage on that LiLo pack it's hard to be certain. But, as they're both 7.4v packs, and given that the battery will only dish out what the ESC asks for (which is is driven by the demand from the motor), it's highly unlikely that it was simply too much current that caused your issue. What's much more likely is that you put in a battery that much larger and heavier than the stock pack, without re-gearing to account for the extra weight. That pack is 3-4 times larger, and no idea how much heavier. It would be the equivalent of taking a 1:1 rig rated at 2500lbs hauling capacity, and trying to haul 7500-10000lbs, if we ignored structural load capacity and focused simply on the driveline.
 

olds97_lss

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Without knowing the nominal individual cell voltage on that LiLo pack it's hard to be certain. But, as they're both 7.4v packs, and given that the battery will only dish out what the ESC asks for (which is is driven by the demand from the motor), it's highly unlikely that it was simply too much current that caused your issue. What's much more likely is that you put in a battery that much larger and heavier than the stock pack, without re-gearing to account for the extra weight. That pack is 3-4 times larger, and no idea how much heavier. It would be the equivalent of taking a 1:1 rig rated at 2500lbs hauling capacity, and trying to haul 7500-10000lbs, if we ignored structural load capacity and focused simply on the driveline.
I had similar issues with my stampede when I went from a 7200mah 2S to 7200mah 3S. The big pack changed handling and drove temps up a bit. I have it geared as low as I can fit, I think, but it's still fast on 3S. I had to adjust springs and oil weights to compensate for the larger pack though as it was too soft. Still trying to sort it out as it lands weird a lot and bounces. May have went too heavy on oil... not sure yet.
 

HPIguy

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I had similar issues with my stampede when I went from a 7200mah 2S to 7200mah 3S. The big pack changed handling and drove temps up a bit. I have it geared as low as I can fit, I think, but it's still fast on 3S. I had to adjust springs and oil weights to compensate for the larger pack though as it was too soft. Still trying to sort it out as it lands weird a lot and bounces. May have went too heavy on oil... not sure yet.
Yes, exactly. There's more to it than just throwing in a bigger pack and calling it done. Most of my rigs always needed re-geared just for where I ran them to keep from over heating, even on the smallest packs they'd accept. Driving style comes into play also.

If you have a way to do so, slow mo camera footage helps immensely for tuning suspension.
 

olds97_lss

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Yes, exactly. There's more to it than just throwing in a bigger pack and calling it done. Most of my rigs always needed re-geared just for where I ran them to keep from over heating, even on the smallest packs they'd accept. Driving style comes into play also.

If you have a way to do so, slow mo camera footage helps immensely for tuning suspension.
Well, I do fine with it at the skate park, which is concrete for the launch, so pretty predictable. When I run at the grass bmx track, the jumps are higher speed, still big air, but the launch is more distance/higher velocity and I tend to end up on the nose, or I land heavy on the rear with the nose high and it cartwheels for 30 feet. lol! Also, the jump faces are less predictable.

Basically, I'm just not that great of a wheel man!
 

Yiggityyamz

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What's much more likely is that you put in a battery that much larger and heavier than the stock pack, without re-gearing to account for the extra weight. That pack is 3-4 times larger, and no idea how much heavier.
original battery is 101.3 grams and bigger batt is 230.8 so there's 129.5gram difference, more than the weight of orig batt 😅 didn't think about regearing it since it's so small but I bet that's the main issue. I've bought an all metal gear upgrade to replace the plastics but they're in the same ratio. I'll probably just run the stock battery for now until I got another 80 bucks to convert it to a strong brushless with heatsinks. May just cut the deans off the 4000mah batts and solder on some xt60s for use with soldering irons and field chargers for drones.
Honestly I didn't do much research before screwing with the car, saw someone throw a 5000mah lipo in a stock config and it didn't blow it but I guess they only ran it for 5 mins or so...shoulda waited to see if the motor could actually last until the battery drained lol
 

Yiggityyamz

RCNT Rookie
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Driving style comes into play also
This is also probably an issue. I drive it pretty crazy to keep my son entertained, full throttle on straight always and jumps, hard starts on hills and in debris, etc. The motor is usually too hot to touch even after the little stock 1500mah pack. But for $50, I really can't complain. We bash the hell out of this thing without any replacement parts needed yet so if I need to spend some money to get it ripping proper I'm not too upset haha
 

olds97_lss

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The smaller/lighter the vehicle, the more drastic added weight tends to be in terms of wear/heat/breakage.

WIth a big 1/8th truck, adding half a pound is hardly noticeable. Unless your adding it all to the tires. I ran into that even with my outcast, going from stock tires to proline trenchers. They weren't much "larger" than stock, a hair taller and 1/4" wider, but they were 1oz heavier (13.4oz vs 12.5oz). Added enough strain to the motor/esc that I had to gear down a tooth.
 

Yiggityyamz

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Do you think stepping it down from from the stock 17t to a 12t would be enough or would that be too much? Found a forum where someone used the traxxas tra3942 (12t 32pitch) to make it a more controllable crawler but says it might make too slow for those trying to bash it, although I think he's also using an upgraded motor that's designed more for torque than speed.
Sorry to keep bugging ya, just haven't ever regeared something this small and you seem to actually know what you're doing.
 

olds97_lss

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I'd maybe just try dropping down 1 or 2 teeth on the pinion. Should be enough to compensate for a pack that's a bit heavier.

Make sure your getting the right motor shaft size diameter pinion. It's probably a 1/8" or 3.175mm. But it could be a 5mm.
 

Yiggityyamz

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It's says 3mm so I'd assume 3.175. I was thinking about getting a 12t-16t pack to test em all out but the 4 pack is aluminum and don't look nearly as beefy vs the machined steel of the traxxas gears so I think I may go with the 3944 14t pinion. Hopefully be a good in between and allow me to bring this motor until I can upgrade to sensorless brushless. If it's too slow well, it's only 10 bucks to try another right?😅 Lol ill probably have to upgrade my spur gear to a metal one as well as the plastic gears slowly shred over time.
 

Yiggityyamz

RCNT Rookie
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Fun fact! This model has actual beadlocks. A lot of others who reviewed this said they were fake but if you try takin the tire off without removing the face you'll tear the tire for sure. Trust me 😅
 

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