MMM Explodes into FLAMES! - Page 2 - RC-Monster Forums

Bondonutz · 07.06.2009, 08:55 PM

Quote:

Originally Posted by fastbaja5b

After reading the article from MGM regarding volt spikes and braking, this makes sense....

Where can I find this article or can you post it please ?

fastbaja5b · 07.06.2009, 09:08 PM

Quote:

Originally Posted by Bondonutz

Where can I find this article or can you post it please ?

http://www.rc-monster.com/forum/showthread.php?t=21973

There's the thread on it.

My question is, if you run say a converted Revo and use mechanical brakes as opposed to motor brakes, can that go part of the way to eliminate this issue?

07.06.2009, 09:18 PM

what about the fact that he was at 30% braking; or does that not change the amperage spikes?

fastbaja5b · 07.06.2009, 09:22 PM

..another valid question, could the larger tyres have compounded the problem?

Sammus · 09:36 PM

lol...yeah they designed the MMM to be run without brakes

I don't think theyd be much use that way...

Probably doesn't help that he was running a V2 - what firmware version was it?

Bondonutz · 07.06.2009, 09:36 PM

Where the hell is JPOPROCK ?
We need more info !

Tire size and weight a issue ?
If gearing and recomended voltage is used, possibly but I don't think so.

jpoprock · 07.06.2009, 10:52 PM

SERIES. SERIES! My mistake. I even went back and changed it from series to parallel after my proof reading my post before sending it! HA! Man.. what a tool. Sorry.

You know... it did cross my mind that the tires might be a touch big. But my Badlands weren't extremely far from it, but smaller yes. They gripped like mad too. Too much for certain things. I don't do a lot of high speed driving. Just medium speed bashing around the yard. So, I hadn't been really driving it around all that fast this day. 20min of it tops to be exact, and my very first time ever w/ these stupid tires!

I'll have to think about my gearing because I can't remember. I think it might be 54/20. And given my temps were always good w/ the Badlands... I didn't think a thing about the tire switch. I realize that 54/20 is pushing it a bit for med speed bashing (i.e. not speed runs), but w/ that 1515 2.5d can always doing well before, and at WOT from time to time, it just didn't occur to me that the Moabs would cause a fire! I figured it would get bit hotter, but not to the point of failure!

Gosh... I sure hope this wasn't a serious oversight on my end. I'm sick about it already. Do you think that 25C is too low, or ok in this case?

W/ the Moabs, what gearing would you suggest?

j

jpoprock · 11:04 PM

The reason I was running 30% braking... was because I wasn't ever able to just "kiss the brakes" in the air to correct anything. A "kiss" resulted in an immediate FLOP on to the lid. They were at 50% when that was happening. So, reading the Castle Link explanation of it all, I thought that 30% of the strongest setting meant I'd be scaling full power braking back by 70%. And if 50% was still sending the truck on to it's lid...30% might be just right. No? Cuz on literally ALL my other veh's, a tap of the brake is always enuff to correct certain things. But a "tap" on my ERBE was like a whole new ballgame. I could never understand it either. It's my first MMM experience. So please pardon me when I display extraordinary ignorance to certain things! Also, I was CERTAIN this was a V3, not V2, and only a few months old. Is there some way to know for sure? Cuz I was sure it was V3, but could be wrong. When you say firmware... are you speaking of the Castle Link Firmware? If not, than I'm not sure. I was up to date as far as CL was concerned. Like... 1.20 or something like that. My MMM is a bit under the weather... so I can't check. LOL!

Man... that fire was the rottenest smell EVER too. My truck still smells like it, my Explorer, etc. Horrible smell that lingers! The ESC is already in the mail back to CC.

So... do I need to weight these tires then and report back? I'll say this much... they certainly are bigger, but they aren't all that heavy really.

BrianG · 07.06.2009, 11:05 PM

The instant brakes thing sounds like one of two possibilities:

1: The ESC was not properly calibrated to the ESC, so it saw any brake action as WOB (wide open brake).

2: The ESC was somehow running in reverse when you applied forward throttle. I know that brakes in reverse are more touchy. This would be caused by having the servo reversing setting on the radio set wrong. You'd have to set it the other way and recalibrate the ESC to the radio again. I don't know if it's even possible to have the ESC arm if the throttle is reversed, but something to look into.

Sammus · 07.06.2009, 11:15 PM

AFAIK V3 ESCs have the battery wires soldered directly to the board, not sockets on the ESC on the battery side.

BrianG · 07.06.2009, 11:20 PM

Both my V3's have socketed battery and motor leads. According to a previous post by Patrick (I think), it's the luck of the draw; some V3's are like what I have, some are like what you have.

Snipin_Willy · 07.06.2009, 11:30 PM

My CRT.5 did the same thing with the breaks, even on the surface: tapping them locked up the wheels. You'll want to check the settings in the castle link and make sure you have forward w/ reverse lockout as the setting. If you're using it as just with reverse then I think the brakes lock as soon as you touch them (boat setting???). I'm not really sure if this is the problem, but it fixed my crt.5 brakes with the MM

fastbaja5b · 07.06.2009, 11:33 PM

Quote:

Originally Posted by Sammus

AFAIK V3 ESCs have the battery wires soldered directly to the board, not sockets on the ESC on the battery side.

Some of the earlier V3's had sockets on the battery leads as well.

Sammus · 11:35 PM

Quote:

Originally Posted by BrianG

Both my V3's have socketed battery and motor leads. According to a previous post by Patrick (I think), it's the luck of the draw; some V3's are like what I have, some are like what you have.

Yeah, now that you mention it I seem to recall that the V3's with sockets are older V3s, but the later revised PCBs all have hardwired battery plugs.

Sounds like a problem with the brake setting though, I hadn't realised the lockup thing.

What remote were you using? I was pretty stupid for overlooking this, but I had forgot to calibrate my futaba tx, and it was doing the locking up thing.

Turned out that from the ESCs perspective, I was driving around in reverse (at 50%) and hitting the brakes on the tx was just sending the esc into full throttle forward. Certainly not a good idea. Make sure you reverse the throttle channel on futaba Tx, then recalibrate ESC.

Unsullied_Spy · 07.07.2009, 07:15 AM

20/54 with those massive and heavy tires is probably part of it. You said the motor never got too hot though, so that makes me doubt the gearing a bit (if the motor is getting hot it's pulling enough amperage that the ESC is most likely getting hot as well.)

Looks to me like a FET couldn't handle it and it blew, Castle will definitely take care of you on this. I really hope they can get different FETs or maybe find a distributor that has better QC, it seems that they aren't quite up to snuff. Sure the failure rate is low but still too many are going IMO.