Uh oh, did I ruin my SMC Lipo's?

Here is something else to remember.....
If you increase your LVC from 3.0/cell to 3.2/cell it will decrease your runtime (which inturn will reduce the mAh you put back into the cell).
I don't know if a loss of 5-10 minutes runtime is the appropriate runtime loss, but some runtime loss should be expected. Keep running at 3.2 for a several charges and see if it hold steady (runtime as well as mAh replaced). If it hold about steady you should be fine...


But then again my opinions seem to be a bit off lately, so I might be way off base.

[TexasSP]

I would say that is a fair trial there. If it's consistent at 3.2v cutoff for 8-10 charges I would say everything is okay. But if you loose 100mah or more across the 8-10 charge cycles keeping the lvc the same at 3.2v then you are over stressing your packs.

[zeropointbug]

Linc, I know lipo's are not like A123's for cycle life, but you get more than 100 cycles out of them don't you?

Another example... say if you DID get 100 cycles from 80% DOD, then you can expect somewhere around 150 cycles at 60% DOD. And if you are really crazy about total calender minutes out of your pack, you can always use 10% DOD and get something like 2000 cycles from it.

Also, charging rate has alot to do with it as well, same with operating temp (big time)... so the newer cells that run cooler and can handle 5C charging are definitely going to last a good deal... if kept to running your typical load along with 1C charging.

[lincpimp]

Originally Posted by zeropointbug

Linc, I know lipo's are not like A123's for cycle life, but you get more than 100 cycles out of them don't you?

Yep, I figure you can get at least 150 cycles, but even at 100 cycles the cost savings over nitro is massive.

Well this is the email I got back from Bryan at SMC when I asked him about this


Bryce,

For starters, I would def. raise the cutoff on the ESC. I feel safe with mine set from the factory. I don't have the castle software to change mine, but when the truck goes into LV mode, the packs are coming out of the truck reading around 6.60 to 6.70 per each pack. As for the puffy packs...If you let them cool down and wait a while they "should" shrink back to their normal size. If they do not, there is damage done beyond repair. If you would like, you can send them in for us to test if you do indeed feel they are damaged or you no longer get maximum power and runtime from them. I know it doesn't help but we do have a 50% off the MAP price for warranty of a defective pack. $42.75 per pack for a replacement is still not cheap, but it does help a little if the consumer makes a mistake, intentionally or not. Please let me know if you would like us to check out the packs and keep me informed on the swelling issue. Did they go back down or are they staying puffed up?

Thanks,

Bryan @ SMC


Its really hard to tell if packs are puffed or not now, if not near impossible. So i'm just gonna keep running and keeping an eye on them and take this as a important Lipo lesson learned. Changed the LVC to 3.2v. Damn that Castle link is godsend for these kinda things.

[zeropointbug]

Thanks Linc, what external LVC should I use? I could also just do it by minutes of runtime and then just shut it down. But to be safe, lvc might be in order.