MMM V3 Dead Short on Lipo! - RC-Monster Forums

jhautz · 07:56 PM

So I got my V3 from castle last week as a replacement for one of the dead earlier version MMMs I sent in. I went to set it up in the truggy on Friday night. It had a MMM V2 in it so it was just a matter of unplugging the motor and battery wires from the V2 and plugging them into the V3 and then mounting it into the truggy. Simple and very nice easy swap out. I like the 6.5mm sockets for this.

Anyway, I went to plug the battery in for the first time and the instant I touched the deans plugs together WHAP!!!!! I got a HUGE spark. I mean HUGE!! it melted the ends off of the deans plug prongs. Like the power of a dead shorted lipo. If you have ever dead shorted one by accidnet you know what I mean.

At first I was like WTF did I screw up. Thinking I wired something wrong or pluged something in wrong. After cleaning my pants out... I went back over everything to see if I could find what was wrong. I couldnt find anything, so like an idiot.... I tried plugging it in again. WHAP!!! another HUGE spark. Scared the poop out of me again even though I was mostly expecting it. Well now i'm pisssed an I pull the whole thing back out of the truggy and redo all of the wiring thinking something has to be screwed up even though it was the exact same wires and all that I had just unplugged from my V2 and they worked perfectly.

After redoing the wiring again, this time I figured I wouldnt punish my poor lipo any more so I got out an old 6 cell stick pack to try plugging into the controller. And again.... HUGE sparks. This time a bit less because the 6 cell NiMH didnt pack the punch of the 5000mah 5s lipo. Well at this point I just diconnected the motor wires and pulled it back out of the truggy. I figured the thing is just screwed up and I figured it was probably already fried so with the MMM just sitting on the bench not attached to anything else I attampted to plug the 6 cell NiMH pack back in just to see what would happen. This time the spark was a little less than the previous time. So I tried it again and a little less spark. After 4 or 5 more times plugging it in I got no spark at all any more.

At this point I figured the thing was probably dead, but Id try it and see anyway, and to my surprise it fired right up. I ran it on Saturday at the track for about a pack and a half and it all ran normal with no issues.

The only thing I can guess is I got one with the heat sink dead shorted against the battery input 6.5mm sockets and when I plugged in the battery it was a dead short and after few good jolts it just burned away the heat sink aluminum like Patrik said it would on a different thread around here.

So now it seems to be working normal, but I have very little trust in it and I am now wondering what kind of long term damage the dead short did to my lipo. It didnt swell, but I know I have had a pack in the past that I accidentally shorted out for a slpit second and it didnt last nearly as long as its matching pack that was never shorted out.

I'm rather pissed about all this, and I'm not even sure that it was the heatsink causing a short, but its my only guess since I cant open it up to check anymore without voiding my waranty. And I'm certainly not going to void it on this one after what it just did to me.

Just wondering if anyone else has seen anything crazy like this. I'm gonna try and call CC tomorrow about this. I had a nuts day at work today and just coulnt get the time to do it today or I would have already called.

Dagger Thrasher · 11.10.2008, 07:56 PM

Wow...that's seriously bizarre. Sounds like a manufacturing defect...maybe a stray blob of solder? Patrick's insistent that the heatsink couldn't cause a short like this, as it would just ablate almost instantly...though CastleMike said he was also going to work with manufacturing to prevent any more touching plugs.
Castle won't have a problem with you opening up the case to take a look, as long as you're careful about it.

jhautz · 11.10.2008, 07:59 PM

Quote:

Originally Posted by Dagger Thrasher

Castle won't have a problem with you opening up the case to take a look, as long as you're careful about it.

I'm gonna wait for them to tell me that at this point.

11.10.2008, 08:03 PM

When i'll recieve mine, i'll take a multimeter and test the conductivity between the plug and heatsink

pasan · 11.14.2008, 05:00 AM

Quote:

Originally Posted by david lamontagn

When i'll recieve mine, i'll take a multimeter and test the conductivity between the plug and heatsink

Which is what he should've done after the very first spark.

11.14.2008, 10:44 AM

Quote:

Originally Posted by pasan

Which is what he should've done after the very first spark.

exact

jhautz · 11.14.2008, 01:46 PM

Quote:

Originally Posted by pasan

Which is what he should've done after the very first spark.

Hind sight being 20/20, I agree. Easy to loose you head in the heat of the moment when the panic and frustration set in. LOL

I did throw a multi meter on it after the 2nd spark, and before the repeated sparking with the 6 cell NiMH pack, but got a really wierd reading. I couldnt get it to give me a consistent measurement. It started off with a very low resistance reading at almost infinity and then over a few seconds kept going up and up to a very high number. It was strange. I also measured the resistance between the plugs on the working V2 I pulled out of the truggy and got some "dancing" numbers. Not sure why that would be, but that little test basically didnt tell me anything. so I went back to the "brute force" testing . lol

Dagger Thrasher · 11.10.2008, 08:11 PM

Quote:

Originally Posted by jhautz

I'm gonna wait for them to tell me that at this point.

Fair enough.

11.10.2008, 08:37 PM

Quote:

Originally Posted by jhautz

I'm gonna wait for them to tell me that at this point.

They said in the other thread that if you open it carefully, they will warranty it. They have had a problem with Traxxas forum members

jamming screw drivers into the ESC to open it damaging the brain board.

11.10.2008, 11:29 PM

Quote:

Originally Posted by Edumakated

They have had a problem with Traxxas forum members

jamming screw drivers into the ESC to open it damaging the brain board.

what?

are you trying to say that the members on the cough "idiot forum" cough would acually do that?? no way

11.11.2008, 12:38 AM

Quote:

Originally Posted by big greg

what?

are you trying to say that the members on the cough "idiot forum" cough would acually do that?? no way

Yeah... I find it hard to believe too.

crazyjr · 11.10.2008, 08:50 PM

I know it was said that on the motors it wouldn't hurt, because the resistance in the motor is lower that the alumnium. But the battery is a different story, Is the resistance of the whole esc low enough to redirect a dead short on the leads? From what i can see, this is the absolute worst case, But it does show that the dead short testing at castle, that the esc would survive, that is a good thing

George16 · 11.10.2008, 09:04 PM

Well, I have the same problem with the positive bullet touching the heatsink. I'm just going to run it this way and like you, I don't trust it either.

http://www.rc-monster.com/forum/showthread.php?t=16432

JerryF504 · 11.10.2008, 10:22 PM

I just got a shipping notice from Castle today. Maybe I'll connect it to the 2 Optimas in my 1:1 truck to the Monster first to make sure everything is nice and ablated before I connect a lipo to it.

BrianG · 11.10.2008, 10:47 PM

Quote:

Originally Posted by JerryF504

I just got a shipping notice from Castle today. Maybe I'll connect it to the 2 Optimas in my 1:1 truck to the Monster first to make sure everything is nice and ablated before I connect a lipo to it.