Hello. I am in the planning phase of building my first efoil, and I need some help deciding on battery pack.
I’m considering buying 50 pcs Lii-70A 32700 LiFePO4 cells and build a 16S3P pack myself. The cells a rated at 30A continuously and this guy tested then with a full discharge at 30A in free air. I am not sure if this corresponds to 80-100A continuously (limited by VESC) when enclosed in a waterproof pack. The total energy corresponds to 1.5kWh.
My build will also consist of a Flipsky 65161 motor(not sure about the kv, and propeller yet) and 75200 VESC
Will this be enough power to push me out of the water to get foiling? (I’m 72kg + equipment)
How long ride time can I expect from a pack this size? (I know there are many factors to this )
Should I worry about overheating the nickel strips connecting the batteries?
Just note that the energy density of any lifepo4 battery is lower than the other lithium variants.
137wh/kg for this one vs 230wh/kg for molicel p42. Your battery pack will be close to double the weight, probably double size also (but i didn’t compare that.)
That weight difference is substantial in a board already about 25-30kg and i would not use these cells for an efoil.
+++ efoil battery max voltage new member warning +++
16s lit a red light then I remembered that 16s for LiFEPo represent the same max voltage as 14s in LiION and is under the 60v estimated safety limit for efoil. Cell Vmax for LiFePo is lower than that of LiIon:
LiFePO : 16 x 3.65 = 58.4V
LiIon: 14 x 4.2 = 58.8V
And you need to consider discharge energy as well. A 5Ah Lifepo might not provide the same energy as an equivalent LiIon, even if their nominal Wh ratings are the same. Lifepo just doesn’t want to discharge fast that efficiently. Energy is wasted to heat due to the internal resistance.
We all have our priorities but i’m pretty sure your muscles don’t care about percents. Efoils are bulky and awkward to haul around yourself, lift into the car etc. I just got back from an evening efoil drive, i have gone out a few times per week for two years now. Believe me, once weight is above 20kgs and it’s bulky then every kilo counts, also when riding.
Another thing to consider is that the LiFePO charge cycle number is two to three times bigger than for Lii. This divides the price of the LFP battery by the same factor.
yes, i agree in that, but i think it’s also wise to consider the balanced lifelength of the board. I guess over the year most efoilers get out maybe 1-2 time per week max, then 2000 weeks life of the battery is 38years. By then the battery will have died from old age, the motor is long since kaput and the joints and ligaments in your body have turned to mush. Probably there’s better technology out there also. So for most efoils, not ridden as rentals and such, it’s probably OK with the normal 500 or so cycles.
Any battery purchased after Jan 1, 2022 will have a 2-year warranty . This is determined by the date the end customer purchased the battery. All Lift products now have a 2-year warranty.
or 300 charge cycles, that’s 150 weeks = three years if two charges per week.
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