Reading the history of the board thanks to @fessyfoo extensive documentation + time & effort
It had only ever pulled about 12kw and a 20s4p sits right above it as far as power output.
20s4p 13lbs
12.999W Nominal
15,120W Max
20s6p 20lbs
72v 19,440W Nominal
84v 22,680W Max
Current setup x5 HRB 4s Lipos 8.45lbs
I’m thinking a 20s4p makes more sense… idk.
The only reason why I would do a 20s6p would be to future proof it for a 4wd setup / more capacity for more riding time.
Have you counted in voltage sag? My 21s4p p42a @180a can do about 13.5kW at 100% but even just a couple short laps in that’s realistically 13kW.
Not sure how many battery amps you run, in my 4WD setup I want to increase my current 180A to something around 250A. 4P P45B wouldn’t be comfortable pushing that much, although you might get away with it if you don’t mind a ton of voltage sag. I don’t recommend it though. 6P would be fairly comfortable doing that.
Although keep in mind 13kW already is a lot. Not many people actually pull that much.
If you want to keep it 4P for that kind of power then you’d need one of the new tabless cells.
50A per cell would be the reasonable max, 60A pushing it, sag is gonna be really significant, but probably doable given how short the pulses are while accelerating at these power levels. But you’d need to run low cutoffs and would notice a drop in power more when the battery gets lower.
I’d recommend 5P if you want to futureproof for 4WD. Just because you have the current, doesn’t mean you get the same power out. If you don’t overstress the cell you’ll have less sag and therefore more power, even at the same current. I don’t think that extra 3lbs would make much difference in handling.
You can connect lipos to a bms exactly like liion cells, letting you charge your board without having to pull them out. I’ve got a zBMS in Ankle Wreacher atm, very happy with it.
But respect the desire to build a battery for the sake of it! That’s dope.
All solid reasons. Dealing with lipos can be a chore. Once I got my system down and built a charger capable of charging 6 9500mah lipos at 1C all on their own channel that helped a ton.
Ive gone back and forth a few times on if I want a li ion pack when these die but I actually really like being able to easily remove the lipos and store them separate from the board. The hot swappability is nice too.
@dskate Yeah I think another reason why is because it’s currently a 20s1p and think most of the lipo peeps run a 12s2p so I feel like my board dies preemptively maybe I just have fomo about track time.
When I was out at I2S OC I ran mine down way faster than normal (first time on the extra wides) and was bummed. Kevin let me use his board to get like another 100 laps in. His SS is li ion and had gobs of range compared. Wasn’t pushing as hard on an unfamiliar board of course but it was awesome to get the extra time. But dang, that board was HEAVY compared. Went to pick it up and was like wtf? Didnt realize it wasn’t lipo before I picked it up
i will say that i’ve never had my board flip in a crash because of how heavy the pack was (18/7) and once i got the right bushing setup, i wasn’t having to muscle the board around corners
5p was ok if not a bit stretched with p45’s on my board for 14kw at 16s in 4wd config. Final drive makes a huge difference, that was geared to 85km/hr. With short track gearing around 60 top speed same settings most I saw was 11kw. And that pack was easily more than the outrunners could handle
