Not sure if this belongs in Esk8 electronics or Mechanics category, but I am speccing out my next build which will use a Trampa MTB-572 deck and I am trying to figure out the maximum size case I can fit between the bindings.
I have already ordered 150 Samsung 30Q cells and I would love to fit at least 100 in whatever battery box I end up using, preferably 120 in a 10S12P configuration. I looked around the Pelican case website and found the 1300 case which looks like it will definitely let me fit 120 cells inside on the bottom half, leaving the rest open for BMS and 2-4 VESC6.
The question I have for you all that have a similar trampa deck is whether or not the top of the case is going to rub onto my legs while I am riding. It looks like it will fit between the bindings but given the possible angle of my legs, I don’t want to be annoyed with it hitting me.
My feeling is it’s more so he can do 200 amp con discharge… This is the problem with 18650’s. They have too low of a discharge for high amp situations.
You both are right - I want to never worry about range, ever, so that I can do long trips while mashing the accelerator. As well, all terrain wheels killing efficiency, plus 4 VESCs is not going to be easy on something like a 10s4p.
The seconday purpose for this battery pack in the longboard is to power a 36V inverter for backup power.
If my calculations are correct, I should be able to pull minimum 5000 watt continuous through 4 VESCs resulting in me probably falling backwards as my board shoots forward from under me
VESC 6 to get the aluminum casing. I have yet to figure out any special cooling but have ideas such as
leaving them out in the open with airflow
airflow channel with filtered/mesh entrance, possibly a fan, leading to heatsinks on each of the VESC
After watching Ben’s video about the continuous current capacity on the VESC 6, it looks like each can handle 45 Amps after more than a minute of working hard at more amps than that, so that gives me 4*45 = 180 motor amps.
180 motor amps * (conservative) average voltage of 3.5V = 6300 W VESC power handling.
10P Samsung 30Q -> 10 * 15A rated amps from battery = 150A -> 150A * 35V = 5250W from battery at slightly less than nominal voltage (to account for sag).
Min of those two is still around 5kW. If I can fit 12P instead of 10P than the battery’s rated current jumps to 12P * 15A = 180A, bringing it in line with the 4x VESC6 current capacity.
Yes, the I^2R losses do really come into play here. I’ll do more research on how I want to connect the batteries together, including the resistivity of multiple nickel strips on top of each other. Nothing else has been ordered yet and I’m not going to do this 3/4-assed like my last build heh
and also learn of current flows, because in parallel connections current does not divide equally and every 90Âş corners and etc cause some serious problems.
Yup. Ideally each battery in each parallel strip will have an equal resistance path to move to the next parallel strip, and the lower the resistance for each one, the better. That’s another opportunity for research/calculation/simulation to try to come up with the best solution.
I would love to avoid a connection system that has each P group connected from the same end, giving the single cell in each P group closest to the connection much more stress due to the lower resistance connection between it vs the ones at the end of the P group in such a configuration
Yeah, I am trying to be conservative in my usage of each part of the drivetrain, and with the acceleration and continuous power I would like, it seems the best way to do that is to spread the stress over a large battery and 4 separate ESC/motor sections.
Then you step into high current world, you can forget simple stuff, my parallel connection board for LiPos will consist or literal copper bus bars, and load switcher of BMS Mosfet’s will sit literally on 5mm copper plates instead of PCB
