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

[zeropointbug]

Yes, 80% is a critical point in lithium polymer/Li Ion cells, the cycle life is drastically reduced after that point. In fact, the less DOD (depth of discharge) you go, the longer they will last. Exponentially.

[lincpimp]

Originally Posted by zeropointbug

Yes, 80% is a critical point in lithium polymer/Li Ion cells, the cycle life is drastically reduced after that point. In fact, the less DOD (depth of discharge) you go, the longer they will last. Exponentially.

Thanks, ZPB! I had the DOD term on the tip of my brain, just could not think of it! I do remember reading this somewhere, and the guy had posted graphs and all kinds of other info too.

Look at it this way, if you buy a zippy lipo for 80 bucks and get 100 cycles out of it, cost is 80 cents to run it for 30-40 mins. So that is 1/2 cent a minute. Not sure what the charging will do to you electric bill, but it cannot be much?

Take nitro costing 30 bucks a gallon, and the average tanks size is 5oz and yields about 8mins runtime. So that would be 25 tanks per gallon, 1.2 dollars a tank, so about 15 cents a minute.

At 14 cents a minute difference a 200 dollar charger is covered in 1400 minutes, about half of what I posted a zippy should last. So you could buy a new charger every 50 cycles and still not have spent as much as you would have on nitro fuel for the equivalent runtime.

Not sure if that is right, seems very good for lipo... Maybe I got something wrong, although the math is pretty simple.

Big difference, huh... And if you get past 100 cycles the difference is even more.

[Finnster]

Originally Posted by lincpimp

Thanks, ZPB! I had the DOD term on the tip of my brain, just could not think of it! I do remember reading this somewhere, and the guy had posted graphs and all kinds of other info too.

Look at it this way, if you buy a zippy lipo for 80 bucks and get 100 cycles out of it, cost is 80 cents to run it for 30-40 mins. So that is 1/2 cent a minute. Not sure what the charging will do to you electric bill, but it cannot be much?

Take nitro costing 30 bucks a gallon, and the average tanks size is 5oz and yields about 8mins runtime. So that would be 25 tanks per gallon, 1.2 dollars a tank, so about 15 cents a minute.

At 14 cents a minute difference a 200 dollar charger is covered in 1400 minutes, about half of what I posted a zippy should last. So you could buy a new charger every 50 cycles and still not have spent as much as you would have on nitro fuel for the equivalent runtime.

Not sure if that is right, seems very good for lipo... Maybe I got something wrong, although the math is pretty simple.

Big difference, huh... And if you get past 100 cycles the difference is even more.

I know I can blow out $5 of nitro pretty easy if I take the Sav out during lunchtime. Frickin truck eats more expensively than I do.

OTOH, the downside to BL is usage, if you don't run the truck very often, natural decay of the batts eats up lifespan w/o use. Unfort there are a few lipos I have for trucks I barely run anymore (little free time w/ 2 little kids now) so those batts are basically rotting away. Least nitro is a pay as you go. This is what's holding back the BL conv for the sav at this point. ~$150
for a motor and ~$200 for a couple sets of batts buys quite alot of fuel, esp at my current burn rate (1.5gal YTD.)


As far as LVC goes, I set @ 3.2 IIRC, but as soon as the batts feel a little drop in I power I kill it. Rarely hit the lvc this way. So far so good on lifespan (2-3 yrs on batts, who the F knows how many cycles that was)

[zeropointbug]

Yeah, agreed with the usage aspect... but on the same hand, the "calender life" of lipo's is at least 6 years (if maintained). A123's are 10+ years calender. So after all, it shouldn't come into play in RC, as you would most likely replace the battery before that time anyways... you know.

[zeropointbug]

BTW, does the Quark 125 have a 3.2v/cell cutoff? thanks.

[lincpimp]

Originally Posted by zeropointbug

BTW, does the Quark 125 have a 3.2v/cell cutoff? thanks.

Nope, highest is 3v per cell.