Quote:
Originally Posted by fastbaja5b
Unless people have missed the umpteen eagletree graphs I have posted, nothing wrong with his set up at all, stock set up, Savage Flux 4s Lipo, max amp spike is 120 Amps that I have seen on my set up which is pretty much identical. I run 5000mah 30C packs and mine don't puff. Instead of helping we have a bunch of know alls preaching higher voltage, get better packs etc etc yet when he was toying with what packs to buy, people with the same attitude were asserting SMC is a "good brand"
No wonder he feels disenchanted with the hobby right now.
My guess is when the lipos first puffed a bit as you stated some damage may have been done, and it's cascaded from there, as my testing has shown, a 3.2v/cell lipo cut off on the MMM is insufficient and doesn't stop the packs dropping below that under amp load, just another shortfall of a problem plagued ESC.
Query it with SMC, up your LVC to 3.5v/cell and remember that there are some people who just like to bombard you with you should and you shouldn't do's on forums, human nature.
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Kind of like you... That last statement does not really hold much water dude.
I for one would never recommend smc packs, and have not. General consensus is that an enerland cell pack will have the least mfg defects and early deaths. So they are the best bet right now due to them being well proven. I have handles countless puffed lipos, and have seen the least amount of defective cells come from enerland.
The packs puffed for some reason, either being overdrawn, or the voltage pulled too low and then pulled very hard. I think they have been marginal the whole time he has been running them, and they finally gave it up.
I have run countless motors with the MMM in various vehicles and set my lvc to 3.2v per cell. No issues at all, not one, ever. I even ran a completely dead fp 4500 30c 6s lipo (by accident) in the muggy for a few minutes and wondered why the damn thing was stuttering so bad, figured the lipo was cold. It was the lvc kicking in, but the pack was good enough to provide enough juice to pop the voltage back up to rearm the MMM. Put 4700mah back in that pack, no puffing, and no loss of performance since. The MMM lvc works fine, if your cells can't handle the load and dip below the lvc while you are running you have bigger problem, like your cells are not up to the task. Plus the eagletree sampling rate is pretty high, and I am sure the MMM has some amount of flexibility in its measuring.
Plus the 3v per cell thing has a fair amount of saftery window, you can discharge a lipo down to 2v, and unless it was a very high load the cell will charge up fine.
Bottom line is that your graphs may say that he only needs 120 amps, but who is to say the smc lipo ratings are close at all. They puffed, and it does not seem like user error or the fault of the MMM. The tall grass loaded the motor, it asked for more and the lipos failed, not the first time this has happened.
If you are hitting the lvc before the pack is almost empty, then you need a better lipo with a higher rating, no way around that logic.