Has anyone built or thinking of building an 18650 pack for this paramotor? If so what did you build and how is it performing?
I’ve been researching this for a while now and have come up with these numbers using either Sony VTC6 or Samsung 30Q cells, which have 3000mah capacity and 15A continuous current, 30a peak.
A 13Sx23P pack would have the following specs
Normal voltage of 48.1V, fully charged voltage of 54.6v, fully discharged at 3.0V per cell = 39v
69AH total Capacity
23p x 15A = 345amp discharge at constant discharge, since the system maxes out at 300A this would be the following… 300A/23P = 13A per cell at full power. If the system only uses 150A when in cruise then this would be 6.5A per cell, very healthy numbers for Li Ion cells.
299 cells = 46grams per cell = 13754grams (30lbs)
Additional weight of connectors/wiring estimated to be .03lbs per cell = 9lbs = 30+9= 39lbs for battery pack.
Bonka battery packs = 5.6lbs per battery. 8x5.6lbs = 44.8lbs for an 88AH pack.
The bonkas seem to be slightly lighter per AH when you add in the connectors/wiring for LiION pack. But LI ION is a safer pack to fly with, and most likely will last 2-3x longer then LiPo packs. From experience with 6S batteries on hexacopter they only seem to last a couple years until they start to puff up. Taking Li ion pack 39lbs/69AH= .56lbs/AH, bonkas 44.8lbs/88AH = .5lbs/ah
Cost, Li ion pack will cost more up front but since they last longer the cost is less in the end. My findings for Li Ion pack with Samsung 30Q batteries would be $2.90 per cell from alibaba seller x 299 = $870, shipping $200 = $1070. Plus connection cost, BMS this price will vary greatly depending on how you chose to connect batteries together, ie spot weld or Vruzend type connectors.
I’m still researching BMS’s and if they are even needed. Some people say definitely, other say not at all. My thought is that it would be better to use a BMS only for charging the pack and not for discharge, there are a couple BMS on alibaba that can discharge up to 300A but my worry is that this is just another failure point in the pack, might be better to directly discharge off the pack instead of going through a controller to do it. Using a BMS only for recharging the pack will save some weight and reduce cost.