Hello people!
I searched through the forum and didn’t find an identical question or the answers i was looking for so here goes.
I have been looking at batteries, the last part of my build and have a question regarding the discharge current. How much is recommended? I see some batteries having 40A and some going 100A+
I am rocking dual 6374 motors capable of handling 3500w each, i will of course not reach this number but with a 40A discharge i would get roughly 1500w from a 10s.
What are you riding? Are there any general recommendations for the amperage?
EDIT: Just to clarify, my goal for the most part is range and not top speed. Acceleration is nice and have a lot of torque is always a plus.
Always go much higher than you need. Remember, the closer to the max discharge of a battery, the more the voltage sags, and the worse performance you will get, at least during that peak during acceleration.
If I build a 200a board, I want my battery to be capable of multiple times that. Which is why I run a battery rated for over 600a. Then, I get almost no voltage sag, which keeps my watts high, since watts are what really matters, and watts = amps * voltage. So as voltage drops even a little, your wattage can drop a lot quickly.
But I’m also crazy, so don’t use my numbers as guidance. Also, look at the discharge curve and what amp per cell would be best. Li-ion cells drop voltage quickly under 10a or higher loads. So you lose a lot of performance quickly. I know many still run them at 20a per cell, but it fells like weak sauce compared to running twice the cells so you only pull 10a per cell.
The standard 15A from a 30Q would give me like 60-65A in a 12s4p or 5p which is where i’m currently looking. So have much more than i can use i definitely wont be able to do. And the least output i can choose is around the 40A output on a 10s4p so that’s kinda my range.
Zippy lipos. 12s 25ah custom pack. I never run more than 200a, but at that, I have seen almost 10k watts to the motors, launching you 0-30mph in 1.9 seconds.
Lipos are always the best battery if power is your goal. But life span and danger are reasons to avoid lipos for daily commuters.
gotta love how i can do the same on 10s4p on old OG raptor Hubs on 30Q’s… the 1.8-.1.9 seconds is a real rush, but indeed not effeciant till after that inital burst
LiFePO4 cells generally have about 70% of the energy density vs li-ion. So as a rule of thumb you’ll want 1.5x the batteries worth of LiFePO4 to get the same range. The good thing is you can get 2,000 to 4,000 cycles or more if you’re nice to them.
As for how many amps your batteries can handle, never go by the C ratings unless they’ve been tested and verified.
3,400mah (3.4AH) * 30C = 102 amps. Multiply that by 3.8v (nominal) and you get 388 watts. Now how long do you think that tiny little 18650 will last when its pumping out 388 watts?
I suggest you dont try that at home, but if you do make sure to wear safety equipment and RECORD* your experiment.
The tough part is where you said premade packs. They’re going to be so rare that anyone who is selling them will jack up the price.
But if you’re up to the task, I have seen Liitokala 3.2v 7,000mah cylindrical cells for as low as $8 a piece that already have nickel strips spot welded to them.
That way you could wire up your own packs without worrying about your soldering iron heating up your cells and shortening their lifespan.
So these cells you have linked, could i hand solder together the nickel strips without causing damage to the cells? or does it still need to be spot-welded together?
Eeek! The only LiFePO4 skateboard pack I found so far is $275 from DHgate. $10 per cell and they’re 26650s. At least its got a BMS already installed, but theres no telling if its a quality BMS or one of those Battery Murdering Systems.
I meant that a smaller schlong could mean you need to build more powerful vehicles that are bigger and stronger than other vehicles, as compensation for the weak member.
