MMM v3 up in flames!!!

[mtfly2000]

Well... title says it all. Gorilla Revo, 6-cell, 2200kv castle motor. I was at the track today and wanted to try out the new combo as well as the one-way from RD I just put in. Happened to forget a jumper that allows me to use just one 3 cell, figured it's rated for 6-cell so I decided to run it with both packs. about 1.5 laps and the smoke started to come out and then some brilliant white/yellow flames shot out about 4 inches tall! With a little luck I was able to remove the power before the lipos were effected. So now it's in the back room stinking it up! Castle will be getting a call Monday!

[e-mike]

i think your the first to have a v3 who caught in fire...sorry for your lost....maybe the positive and negative bullet plug had toutched the heatsink..so castle offer a good service..like you said call them .they will replace your unit for sure


im really think that the v3 is a solid esc (30hours each of my 7mmmv3)

[mtfly2000]

yeah, but the v3's don't have bullet connectors on the power leads, at least not mine and my buddies. I know, the heat sink seems like a bad idea rubbing against the bullet connectors. But after telling Bernie about having to open my v2 and pry the heat sink away from those connectors to get it to work again, he said they've bench tested them and it's fine. I'm glad they offer great service. that's one of the main reason's I own so many Castle products.

[transtalon]

Mine also fried after converting an OCM Kaos buggy on BL. I ran it didn't seem real fast at the topend. I charged the batts just to get a full charge, plug the batts connector then the smoke came out. I was waiting a long time due to the conversion and weather sub zero temps and rain. Now I am sending it back for repair. I might have to get another one so I can see how good my conversion turned up to be.

[johnrobholmes]

Were you geared for use on 3 cell lipo? What was your rollout?

[mtfly2000]

I was using the pinion they come with on a 70t spur. Mine is a Fastlane 2 speed tranny, I had it in low gear since I wasn't able to run on just 3 cell. It had a ton of power for that lap and a half. For tires that don't like to wheelie on clay, it was making it stand up on end; can't even put the hammer down on the strait-a-way. I'm a bit curious what you mean by "rollout".

[johnrobholmes]

Rollout, the final drive of the vehicle. Motor spins 30 times per 1 revolution of the tire = 30:1 rollout.

[mtfly2000]

OK. the rollout looks to be right around 28:1. of course it would seem that this "rollout" test doesn't take the tire diameter into account. I'm using the Duratrax RT-X27 tires that claim to be 5.5" OD. So it'll be a bit lower "geared" than if I were running big 'ol 40 series tires that can be around 7" OD.

[johnrobholmes]

You can also figure rollout in relation to the tire. Just figure out the circumference of the tire, then you know that it takes 28 motor rotations to travel 17.27" on 5.5" tires. We can assume no ballooning for now.

Said another way, it takes 19.44 revolutions of the motor to roll one foot.

So assuming 4v/cell under load we have 2716 feet/ minute speed. Close to 1/2 mile per minute or 30mph. Seems very reasonable gearing to me.


Running 40 series tires with 7" od we can just take that 30mph and multiply by (7"/5.5") to get 38mph. Still very reasonable.

[BrianG]

BTW: all this tedious math is what the R/C Calc site does....

[mtfly2000]

wow, you're taking me back to high school here with 2pi(r) and cross multiply divide! Even though it was pretty insane to have on a smaller track, it was pretty tame for what this system is supposed to be capable of.

[johnrobholmes]

The tedious math is the fun part!

[mtfly2000]

had a nice little talk with Thomas from Castle today. of course, another one is on the way. but he suspects my batteries were allowing ripple current since the red power wire was the first wire to unsolder itself. seems plausable. 5000mah 20c zippy's. they worked great on my v2 and Nemesis motor as just 3-cells before.

[auto2]

ripple currents? did he explain what that is or how it happened or how to prevent them?

[johnrobholmes]

Ripple current is from batteries that drop voltage under load. Causes a ripple in voltage and current. If the batteries are bad enough that the Caps can't keep up, things get hot really fast.