Oh #%@!! What did I do to my SMC Lipos?
 

Ok, I think I just seriously bit the weenie on this one. I just finally got done upgrade my Savage Flux with a new Spektrum DX 2.0 with some Proline Badlands and Velocity dish wheels. I programmed the DX 2.0 as per the usually HPI way and made sure the EPA's were at 125% for throttle and brake, as I was told this would not hurt the motor or the ESC. The throttle only had 10 clicks for trim. I kept the gearing stock at 20/44.

I"m using SMC Sport Max 6000mAh 28C hardcased batteries which have been awesome batteries up until this point. I've been using a Triton 2EQ with balancer at each and every charge and iv'e had the LVC set from 3.0v to 3.2v using the Castle link.

Today was my first day running the new truck and I kept it simple and was just running it in average grass height at a variety of speeds testing out the new tires and rebuilt shocks. I kept checking the temps and I didn't feel the motor, ESC or batteries were getting dangerously hot.
It was working good for around 15 or so minutes when I noticed it started to loose power pretty quickly, more then it used to.

So I shut it down and brought it inside and I about had a cardiac arrest when I took out the batteries that were very warm to the touch and had damn nearly puffed out of the hard pack casings!!

http://i100.photobucket.com/albums/m...x/pufflipo.jpg

I immediatly put them outside to cool off and hopefully not explode, so I haven't taken a voltage reading on the charger but the LVC was set at 3.1v and it didn't kick in at any point, I just noticed a loss in power sooner then I expected.

Anyone please give me incite or suggestions on what the hell went wrong here? I'm pissed that just ruined $190 worth of batteries and I don't know how or why!

http://i100.photobucket.com/albums/m...x/newsetup.jpg

EDIT: Added photo of voltage test results for both Lipos

http://i100.photobucket.com/albums/m...Flux/lipo1.jpg

http://i100.photobucket.com/albums/m...Flux/lipo2.jpg

http://i100.photobucket.com/albums/m...settings-1.jpg

Well, looks like one or more cells in that pack puffed. Most likely due to the the grass putting addl load on them and they could not keep up. Given their specs they should be able to handle a 168 amps cont, but we all know that the specs are sometimes a bit exaggerated. Plus I have no idea what cells are in there, so you may have just got a defective cell, it happens.

4s setups in heavy monster trucks are just not a good idea. I have stressed higher rated packs that those smcs in a revo on 4s, so I can imagine the savage was pushing them pretty hard. The grass was probably just enough to send them over the edge.

Time for some hyperion g3 packs! Go up to 5s, and gear down to a 17t pinion for the same overall speed. 5s seems to be the sweet spot for the MMM/2200 setup anyway. I ran my lst with the mmm/2200 on 4900 5s rhino lipos (70 dollar pack, 20c rated) and it did fine with badlands, geared for 40mph. Not a light truck by any means, and those batteries had no issues keeping up.

Going up in voltage will reduce the amp draw, provided you lower gearing for the same overall top speed.

Might have been the new wheels, in addition to the grass. Are the new wheels bigger/heavier then the old ones?

did it roll freely after the new wheels were on? I always "kick" my r/c's before I run to make sure they roll nice. Any drivetrain binding puts serious load on the equipment.

About same size, but weight less then the other ones.

Yeah, it rolls fine

Theres no way the grass would have put that much strain, considering that i've run the truck with the same batteries on the stock tires with no such issues.

I'd rather not deal with trying to modify/run a 5S pack on a Flux, its not specced for that type of wiring/Lipo.

Just use a 2s and 3s pack in a series to make 5s. A hyperion 5000mah G3 vx 2s and 3s lipo.

Not to point out the obvious, but the lipo did puff. They only puff if they go way under voltage and have a large load placed on them, or they are over stressed past their capabilities.

And running in grass places more load than almost anything else (save maybe deep wet sand or mud).

As ML said, use a 3s and a 2s. Heavy trucks need more voltage dude, not talking out of my ass here (even though it would be cool if I could do that).

Jim Carey did that on that one movie. :lol:

I did that once on a dare.. was funny for a bit, then just made my tongue taste funny.

Grass is the worst you can put a pack thru. Lots of people think speed runs are really hard on batts, but they are relatively light duty unless the gearing is v. v. tall.
Hard to imagine it got fragged that easy, then again could be the way you drive it or a bad pack. Eagletrees are invaluable things, as are temp guns. Hot lipos are over worked lipos and soon to be dead lipos. Sry.

"Let me ass you a question!" I remember that, good stuff!

have you metered the packs to see what the voltage is now. Maybe something went wacky with the lvc and it just drained them too far.

I'm afraid to do anything with them in their current state

Then throw them out, and Go buy a Hyperion 5s setup....

They will be fine to hook a volt meter up to and check the voltage. There's all kind of puffed ones setting around here!

No, im sending them back to SMC once I hear from them tomorroo

Added voltage readings

I'd def check them if you are planning to send them back, if they get them and they are showing 2 or 3 volts, I'd say you wasted your money on shipping them to them.

It most certainly is. Its speced for 4 THROUGH 6s, that means 4,5 or 6. You've just seen everybody pair their lipos and choose 4 or 6s.

You're into it this far, go up to 6s and reduce your gearing for the same top speed as your 4s setup, everything will run cooler and happier.

I know from running nitros how quick the little engines overheated running in grass, so I mostly avoid grass runs with my electrics. Good Luck!

I hate to say it, but it might just be the packs are crap, not just yours but all of them. My LHS has seen several sets of these packs do the exact same thing. Packs will be working fine, then one run they will randomly lose power and puff. My guess is that it's not necessarily your setup, but the cell chemistry SMC is using may be unstable.

Yeah, I have seen those SMC and other brands like it in hard cases just poof, more than usual. A guy that is sponsored at my local track says he is sponsored by SMC and of course says 'they are the best batteries'... I think to myself, boy how much did they pay you to say that?

If you want get some tough ass batteries, go for the Hyperion G3 packs, more than top notch performance, and very decent prices.

I put an eagletree up not that long ago showing that an lvc of 3.2 on the MMM still allows the pack to get under 6v under load. I have reset my LVC to 3.4 v / cell.

This graph shows pack voltage with a 3.2v/cell lipo cut off, it still drops below under load.

http://i212.photobucket.com/albums/c...rols/flux1.jpg

It may not kill the battery the 1st, 2nd or even 20th time but it all contributes until one time you reach the point of no return and it's puffin time!

why are you sending them back? Its not there fault.... Running in grass puts a HUGE strain on everything and obviously the batteries couldn't take it.. Theres no reason to blame a company for ur mistake..

I would try to get some sort of refund or comp. It is hard running, but if they are rated that high, they should not have puffed like that. I dumped an A123 pack (4S 4600 mah equiv) in 7 mins in the grass and they were rock solid.

FWIW, they are only rated 28C, that doesn't say burst or constant. Obviously not constant w. your experience...

$85 for a 2S pack is pretty pricey. For the money you spent, you could get a Neu pack and be sure of the spec (or hyperion or whatever...) or go cheap and get Zips for way less. Pretty disappointing really.

I thought SMC was a "good" brand of Lipos

I wish you experts would give a list as to what is and isn't a "good" brand.

Hmmmm.............10 week old Lipos. But you posted noticing some slight puffing after only having them 4 weeks?

http://www.rc-monster.com/forum/showthread.php?t=21373

I would say they've been on their way down for awhile now.

If your fan wasn't kicking in, IMO, you couldn't have been pushing the amp draw that hard.

My MMM fan cycles quite often really on 4S.

Thats just the thing, I was sitting in the grass driving it and I had the truck come up to me several times to check on it and I never heard the fan kick on once.

It is possible that the first episode caused some damage which slowly increased until this.


My MMM fan cycles a fair bit on 4s as well. It is possible that if your fan didn't kick in at all as you say, maybe the speedy wasn't getting the amps it needed from the pack, the pack gets overdischarged due to prior damage and then this.

If you really want details, here are some photos of the grassy area I was driving on when this occured. Sure as hell don't look like it would cause my batteries to fry like that but then again, anythings possible at this point I guess.

http://i100.photobucket.com/albums/m...Flux/area1.jpg

http://i100.photobucket.com/albums/m...Flux/area2.jpg

http://i100.photobucket.com/albums/m...Flux/area3.jpg

http://i100.photobucket.com/albums/m...ux/area4-1.jpg

How dare you run an offroad truck offroad!

WTF< now people are telling me 4S isn't good enough for these trucks?! At first it was 6S was to much and breaks shit and now its 4S isnt' enough!! This is really getting old. The electrical tape was their to prevent the battery trays from damaging the wires after I clipped them FYI.

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.

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.

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!

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?

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.

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

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.

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.

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