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-   -   Oh #%@!! What did I do to my SMC Lipos? (https://www.rc-monster.com/forum/showthread.php?t=22376)

fastbaja5b 07.19.2009 10:37 PM

I hear ya buddy! First we get the "4s is not enough for a heavy truck" but if we use 5 or 6s we have an MGM article saying the ESC is potentially at risk due to ripple current on brakes.

lincpimp 07.19.2009 10:56 PM

Well, I have run alot of 4s setups, with many different escs and batteries and motors. My experience is that 4s setups run hotter, and just do not have the punch/voltage reserve that a 5s setup does. Now 6s with a lower kv motor is even better.

I really do not care what some mgm manual says, or how many people successfully run 4s setups in heavy vehicles. Just cause it works does not mean it is optimum or the best that can be done. I have run enough combos to know what works. If you have the option to run higher voltage do it. You will not be disappointed.

fastbaja5b 07.19.2009 11:03 PM

I don't doubt that, and if I felt the MMM was up to running a 5s/6s set up reliably I probably would.

But I don't think it is, the failure rate on 5/6s as against the failure rate on 4s is simply far too high!

_paralyzed_ 07.19.2009 11:08 PM

6s geared for 60 will be at the limit and potentially break stuff.

6s geared for 45 will run cool and reliably.

4s is too little IMO for monster trucks.

As far as batteries puffing and parts breaking, that's just part of the hobby. If your going to beat on a truck its going to break and have failures. Nothing is invincible no matter how much money you throw at it.

fastbaja5b 07.19.2009 11:10 PM

Quote:

Originally Posted by _paralyzed_ (Post 305824)
6s geared for 60 will be at the limit and potentially break stuff.

6s geared for 45 will run cool and reliably.

4s is too little IMO for monster trucks.

As far as batteries puffing and parts breaking, that's just part of the hobby. If your going to beat on a truck its going to break and have failures. Nothing is invincible no matter how much money you throw at it.

I disagree, just read how many MMM's have s#at themselves on 5s/6s whether it be geared for 45mph or 60mph

Are we just making excuses for lemons?

zeropointbug 07.19.2009 11:24 PM

Quote:

Originally Posted by fastbaja5b (Post 305821)
I don't doubt that, and if I felt the MMM was up to running a 5s/6s set up reliably I probably would.

But I don't think it is, the failure rate on 5/6s as against the failure rate on 4s is simply far too high!

What do you mean the failure rate is too high? For which cell range?

Like Linc said, the higher the voltage the better, I would be running a 45 volt setup (as 45 volts is around the limit for break-down through your outer skin layer) if there were the appropriate ESC available to the market.

aqwut 07.19.2009 11:26 PM

Gotta disagree... 3S and 4S is enough for monster trucks... Had LST run 3S 5000mAh and 7XL on Mamba Max esc.. it did fine... Those packs must not be performing @ 28C... Right now, Temporary, I have 4S running my 1/5th scale and 2280, just for fun....
http://www.youtube.com/watch?v=dV51RnoBrGc

Finnster 07.19.2009 11:29 PM

I'm w/ Pimp and Wheels. I always prefer to run higher voltage and not overpower the system. Its easier on the components and you get lower temps w/ more voltage and higher eff. Hell I run 4S in my CRT.5 :)

I've had my v2 MMM running for over a year no probs on 5S. My fan never comes on and the 2.5D motor gets at most 160 after 30min or so of constant track driving. Bashing stays even cooler. 6S would be fine assuming to keep reasonable power levels. 60 in a Savage is a bit much IMO, esp if doing hard driving.


I didn't see the part where the lipos were damaged earlier. I've done that accidentally, and its usually the beginning of the end. This grass thrashing may have just been too much for wounded batts. Ideally I would run the Sav with 5S/1Y or even 6S and a 2.5D or 3D. Else gear down a bit w/ the 4S/1Y or change driving until you have all the bugs worked out.

lincpimp 07.19.2009 11:32 PM

Quote:

Originally Posted by fastbaja5b (Post 305821)
I don't doubt that, and if I felt the MMM was up to running a 5s/6s set up reliably I probably would.

But I don't think it is, the failure rate on 5/6s as against the failure rate on 4s is simply far too high!

Hmm, only one out of 5 I have had died on 4s. The other have ran fine on 5 and 6s. And the dead one was a bec failure, I even did the BG mod to it and it works fine with an external bec.

As far as failures go, are you considering just fet failures, or the bec failures as well? I do not consider the bec failures, as that was a component problem, not a design issue. And it has been rectified.

fastbaja5b 07.19.2009 11:40 PM

I am talking about FET failures on MMM speedies running 5 or 6s resulting in failures such as this:

http://i212.photobucket.com/albums/c...m/P1040529.jpg

http://i212.photobucket.com/albums/c...RBE-MMM_08.jpg

http://i212.photobucket.com/albums/c...m/DSCF0864.jpg

http://i212.photobucket.com/albums/c...1237421114.jpg

_paralyzed_ 07.19.2009 11:53 PM

too many people have an "it's just supposed to work" attitude. This is the extreme side of the r/c hobby and you'd think that the hundreds of dollars people spend on this hobby would give them a clue that these aren't "just toys". They modify them and change them and have no real knowledge of what they are doing, rather they're slapping together parts like a lego set, and then expect to drive it off a building at 75mph and think it shouldn't break. shit happens, things break, and sometimes it's nobody's fault.


[end rant]

aqwut 07.20.2009 12:12 AM

Quote:

Originally Posted by _paralyzed_ (Post 305845)
too many people have an "it's just supposed to work" attitude. This is the extreme side of the r/c hobby and you'd think that the hundreds of dollars people spend on this hobby would give them a clue that these aren't "just toys". They modify them and change them and have no real knowledge of what they are doing, rather they're slapping together parts like a lego set, and then expect to drive it off a building at 75mph and think it shouldn't break. shit happens, things break, and sometimes it's nobody's fault.


[end rant]

You're right... That's why everyone should come to RC-Monster and ask questions before they setup.... :mdr:

zeropointbug 07.20.2009 12:17 AM

Quote:

Originally Posted by aqwut (Post 305850)
You're right... That's why everyone should come to RC-Monster and ask questions before they setup.... :mdr:

Even then, it still happens....

Freezebyte 07.20.2009 12:17 AM

Quote:

Originally Posted by _paralyzed_ (Post 305845)
too many people have an "it's just supposed to work" attitude. This is the extreme side of the r/c hobby and you'd think that the hundreds of dollars people spend on this hobby would give them a clue that these aren't "just toys". They modify them and change them and have no real knowledge of what they are doing, rather they're slapping together parts like a lego set, and then expect to drive it off a building at 75mph and think it shouldn't break. shit happens, things break, and sometimes it's nobody's fault.


[end rant]

Starting to feel I shoulda just bought a fucking Traxxas Stampede VXL as now im so upset and dissapointed im thinking about giving up again on the hobby like my Revo 3.3 did to me two years ago, more work and fustration then fun.

Wild YFZ 450 07.20.2009 12:26 AM

Quote:

Originally Posted by Freezebyte (Post 305853)
Starting to feel I shoulda just bought a fucking Traxxas Stampede VXL as now im so upset and dissapointed im thinking about giving up again on the hobby like my Revo 3.3 did to me two years ago, more work and fustration then fun.

Woah, Take it easy there beefcake, Whats the problem, Your lipos coudln't take the amps everything was pulling from being in the grass. Like everybody said get a HIGHER VOLTAGE setup..


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