HELP! Revo Electric FIRE

I have a Novak 4.5 HV system in my Revo 3.3 conversion. running Reedy 2s 5000mah 7.4v (x2) to power the truck.

Truck had been sitting for a couple months and before I put it away I cleaned it with alcohol.

Got some new stuff for it for bashing, new large tires and body, so I charged up the lipos.

Ran it out a couple feet and maybe a little too fast because the tires came off all the rims in different places, even after sitting a day with a liberal amount of zap-a-gap to hold them on.

PROBLEM I ran it back to me so I could take care of my tire issue and it had white smoke coming out from under the body. I look through the window and a fire starts. I pull the body off and at the same time the capacitor hits the ground. It was zipped tied to the chassis out of harms way. It had burned through the zip tie and incinerated the 2 wires connecting it to the system into little balls of solder.

What happened?

Here's a picture of where it was mounted if it matters. Its red.

[Metallover]

Sounds like something shorted out. Either that or the Novak...

[JERRY2KONE]

From your description and the fact that it happened so soon after starting it up, it sounds like you had a dead short casuing a tremendous amount of heat very quickly. Either you had a bad CAP in there, or something was wired up wrong or it was touching a ground. Something shorted out for sure to cause that much heat in an instant melting the ziptie.

I've had the system for about 6 months and no problems. And it happens to be my first BL r/c. I'm just hoping I can buy just the cap from Novak and not have to drop another $250 for the system. It's weird because with a short, I should be looking for an exposed wire correct? When we built this truck we did everything possible to make sure no wires touched, deans plugs, always checking the sleeves. And not to mention my chassis is 75% Carbon Fiber. But I'll be on the phone tomorrow with Novak tech's to see what my option are to repair and prevent this from ending my day of fun.

[Krawlin]

Originally Posted by LesBur

I've had the system for about 6 months and no problems. And it happens to be my first BL r/c. I'm just hoping I can buy just the cap from Novak and not have to drop another $250 for the system. It's weird because with a short, I should be looking for an exposed wire correct? When we built this truck we did everything possible to make sure no wires touched, deans plugs, always checking the sleeves. And not to mention my chassis is 75% Carbon Fiber. But I'll be on the phone tomorrow with Novak tech's to see what my option are to repair and prevent this from ending my day of fun.

IIRC carbon fiber is a conductive material, which could be how it possibly shorted.

[BrianG]

Originally Posted by Krawlin

IIRC carbon fiber is a conductive material, which could be how it possibly shorted.

Yes it is. Actually, the resin coated top is insulative, but the actual carbin fiber layers are conductive.

[Krawlin]

Originally Posted by BrianG

Yes it is. Actually, the resin coated top is insulative, but the actual carbin fiber layers are conductive.

Oh ok.

Well, he did have it mounted on the side of that upper deck, and it doesn't seem like there is a whole lot of resin on the sides, and the heat shrink on the cap board may have worn through and touched some of the CF and caused a short.

[Metallover]

By the looks of it there's a board connected to the cap?

Anyway, I would put my money on a manufacturing defect in the board or cap. Maybe something wasn't soldered good enough. I'm sure novak can help you out...

If you get the chance, I'd swap it out to something like a MMM.

Doh! @ CF being conductive lol. Maybe I get the repair parts and put something between the CF and electronics. Any suggestions? I don't know if that will help. Or if I'm missing something that you guys do to prep your r/c's for brushless.

[JERRY2KONE]

That CAP heated up enough to melt through a ziptie in seconds. Something had to be shorted out. Look your setup over very closely. Check all of your solder points to make sure that something is not crossed over or touching that should not be. When you strap down a CAP make sure it is not touching anything metal like the chassis, tranny, shock tower, or whatever. If so, then double shrinkwrap it first. You want to elliminate any possible chance for a short of any kind. I know we all do this instinctively, but you either had a bad CAP or you missed something. It is always nice to have a second set of eyes to check things out as well. Preferably someone who knows something about the hobby or electricity in general.

[What's_nitro?]

What I want to know is: How did the capacitor lead melt in half??? It couldn't have been from over-current, because the cap itself would've popped before the lead melted and/or the other lead would be semi-melted as well. It couldn't have been from the fire, because the other lead would've melted, too. I suppose if there was an internal short in the cap that might do it, but how could the cap sustain that amount of power long enough to melt metal? Puzzling, huh?

[Metallover]

Originally Posted by What's_nitro?

What I want to know is: How did the capacitor lead melt in half??? It couldn't have been from over-current, because the cap itself would've popped before the lead melted and/or the other lead would be semi-melted as well. It couldn't have been from the fire, because the other lead would've melted, too. I suppose if there was an internal short in the cap that might do it, but how could the cap sustain that amount of power long enough to melt metal? Puzzling, huh?

I noticed that too. Im wondering if that lead was damaged or even cut and that is what caused this.

That looks similar to Tim Smith's smokey problem on his HV system. Look at the first capacitor:

[What's_nitro?]

Oh man, what a drag!

[rabosi]

Originally Posted by What's_nitro?

Oh man, what a drag!

hee hee. nice one.