Here’s a good example on how to mitigate voltage sag and under performance on a li-ion battery
Budget: $300
Options: 60 NCR18650GA, 44 Sony VTC6. (I get the 500+ discount since we buy a ton of batteries for work.)
Possible configuration:
10S6P GA with max continuous draw of 60A
11S4P VTC6 with max continuous draw of 120A or temp cutoff of 80c
1KW load assumed.
1000/36v nominal / 6p = 4.62A/cell
Now I can use Henrik’s website (Lygte) to find my actual nominal voltage at this power setting.
At 5A continuous, nominal voltage is closer to 3.48V
1000/(34.8*6) = 4.79A/cell
So now we have nominal voltage and current draw for a continuous 1000W.
At this power setting, the cells have 3.2Ah of capacity. So total energy can be measured by:
3.48v3.2Ah60cells = 668Wh.
So I should be able to run roughly 40minutes at a constant 1000W. Which in reality is more like 35 (based on experience)
Same process can be done for the VTC6.
1000W/(39.64) = 6.31A
@7A: nominal v= 3.58, capacity = 2.9Ah
1000W/(39.384) = 6.34A so we’re being a little conservative by using the 7A curve.
Total energy = 3.582.940 = 415Wh
Runtime @1000W: 25minutes.
So if you constantly pulled 1000W then the 10S6P would be the way to go as it has 50% more endurance.
Here’s the upside to the VTC6s though. Your max power draw is capped at 2000W pulling 10A/cell with the GAs. Using VTC6, your max power draw is capped at 3000W pulling 20A/cell. In other words 50% more power.
So if you need endurance, 10S6P GA cells
If you want power 11S4P VTC6s.
You can most likely pull more power from both cells for short periods of time, but it’ll most likely harm the life of your pack, (300 cycles, 80% capacity)
The same trade study can be done with LiPos and I would have done an example but I dont have data in front of me rn.
Cheers!