I have never tried using 10C multi rotor packs myself and have heard from old-timers on this forum that they offer weak performance. I use 5000mah 60C batteries at 10s even with these, I experience some voltage sag when climbing hills. At 130lbs, you might be ok with 10C packs but I can’t say for sure.
I may go for a lower capacity so I can get something that says it is 20-30C, just to be safe than sorry. Cheaper that way too. Thanks for the reply!
Aren’t LiPos 3.7 volts per cell? So how can you only go to 3.6? Or does charging them put them over that 3.7v so 3.7v is resting?
Lipos and Li-ions are 4.2v per cell when fully charged. The voltage drops as they deplete. 3.8v is storage voltage.
Check out Zippy flightmax 8000mah 30C
If you search around here or on manufacturers websites or in their datasheet on the various batteries you can see the voltage over the discharge for the particular cell chemistry you’re working with. Most Lithium Polymer variety of hobby RC batteries have like @Namasaki said 4.2V when fully charged and somewhere around 3.6V when fully depleted (depends on the specifics of the chemistry in the electrolyte, the anode, the cathode, and the arrangement/size of things, but general rule of thumb those numbers are correct for run of the mill RC LiPo bricks).
If you look at the discharge curves for the cells you’ll see the rate of the power being dropped out of the battery depends on the amperage… meaning if you pull 10A for 1hr you’d drain more Amp-hours out of a battery than if you were drawing 5A for 2 hrs. In theory those would be equivalent but in reality the higher drain on the battery means you end up reducing the voltage more quickly than if you have a lower current draw. With all the lithium based stuff I’ve seen they have the same general characteristics to the curve though, quick drop off from 4.2 to around 3.9 then levels off to a somewhat linear voltage depletion until you hit somewhere between 3.6 and 3.3V at which point you hit a cliff and the voltage drops to near 0 pretty quickly. If you ever have a cell go over that cliff it essentially means replacing the pack (unless you are going to do somewhat dangerous surgery on your pack and have the right solder and flux around… basically not worth it).
All batteries have slightly different curves but they will look something akin to below.
I would like to add one observation if I may, It did seem to me that when I compared 25C 5ah Lipos in a 12s configuration to 60C 5ah Lipos in a 10s configuration that the the 60C Lipos have a slower and more linear drop from 4.2v than the 25C Lipos. I am convinced that when using Lipos, the higher the C rating the better off you are. It’s probably safe to say that drawing 30a from a 60C Lipo is like drawing 10a from a 20C Lipo Or 5a from a 10C Lipo in terms of voltage sag.
Good to know. And thanks @wafflejock for the chart, that makes a lot more sense now
Personally im using 4x Zippy Compact 5Ah 3S Lipos for a 6S2P and they have been working very well. Personally I dont discharge past 3.7V though I have had a LiPo I accidentally took down to 2.6V a cell and brought pack without any noticeable difference in capacity, though time will tell because im sure it affected the IR of the cells. However I use to have 2x Turnigy 30-40C 5Ah 3S Lipos in series and eventually they started bulging and I replaced them with the Zippy ones when I re built my board.
Also @Shiven please for the love of god dont use one of those “100 circuit breakers” they are TERRIBLE I use to use one and it was the worst part of my board! Either use a XT90 key loop, or a MOSFET switch. Also you dont need to use XT90 connectors XT60 are more then plenty as well as much cheaper.
I also tried to use one of those automotive breaker switches on my first 12s board and it did not hold up either. The arcing between the contact points wore them out pretty fast…
I remember I was using it for a while and over time it started falling apart, a pin here and there then the entire top lid, kept fixing it. Then one day I went off a little curb and it hit the ground, it literally exploded it was hilarious, also sucked cause my board was no worky. Also the arcing was a problem had to clean the contacts once or twice though I was also only 6S and had a car ESC, nothing compared to 12S and a VESC capacitor bank.
believe me the spark at 12s is pretty intimidating. My points not only got burned up but the spring bar got weak from heating up and I started loosing connection while riding.
I see, but did yours explode? I DIDN’T THINK SO, TOPPED!
you got me there LoL
No breaker switch, got it! Is there anywhere I can find a MOSFET switch for the vesc?
Yeah there’s a bunch of people who sell them, including me though I’m out of stock ATM. Torque boards sells one for $60 which is a bit pricy but there’s others to @goldenHusky husky sells his switch you can ask him about it or just search on this forum “Vedder anti spark switch” or “MOSFET switch” should return plenty of results.
Just use an antispark loop… I don’t get the “huge benefit” of one plug over two and don’t think BMS is typically a good idea ( unless you’re making a consumer board) more crap on the board is just more crap that will eventually shake apart or break in some other way. If you make your own battery pack and need to put leads on their anyway it makes some sense to me but for lipos I don’t get it. Been riding with the same batteries for over a year and no corrosion of the leads ( I spray everything with corrosionx though and keep the balance leads mostly tucked into the battery enclosure)
True. I was looking for a more elegeant solution and was planning on using this switch, but a loop would be cheaper.
cannot recommend these enough!! I run a 10S system with 2x5S 8ah FlightMax’s and they run awesome!