If you ordered a FocBox from me, I have some news

Hey, sorry for derailing the thread even more.

What do you think the greatest benefit is of the DieBie that you’re gonna include it as part of your future builds?

I would even recommend first start with simple 2wd setup… After several hundreds of kilometers than your legs will be able to handle torque then you can start think about 4wd and high current setups, I am still strugling with starting even with throttle mapping and full weight on front leg.

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Is there anyway for the output power to be more evenly distributed? The power out tab on the spark switch is just one wire isn’t it? So from that one wire, if I split that into two (one for the front drives, and the other for the rear) and instead of splitting each of those additional wires again for each VESC I could have both negative wires from the VESC’s connected and set in an xt90 and the positives connected and connected to the other terminal in the xt90, that way there’s much less places in the wiring where things could get made uneven…?

60a motor limit + 60a bat limit vs 60a bat limit only:

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Are these real data or just calculated?

No worries, I’d prefer being told when I’m wrong, lol otherwise I’d keep making the same mistakes :smile:

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calculated…

you can start with the ground speed and wheel diameter to get the wheel rpm,

next use the wheel rpm times the gear reduction (wheel teeth / motor teeth = gear reduction) to get the motor rpm.

next use motor rpm / motor kv to get the back emf v,

then use ((pack v * duty %) - bemf v) / winding resistance = motor current

then 60 / (2 * pi * kv) for motor torque in newton meters per motor amp

then motor current times the torque per motor amp for motor torque

multiply the motor torque times the gear reduction for wheel torque

vehicle thrust comes from relationship between the wheel torque and wheel diameter-- (wheel torque in newton meters * 1000mm) / ((1/2) * wheel diameter in mm) = vehicle thrust in newtons per motor

then you can get the mechanical watts from motor torque in newton meters times motor angular velocity in rad/sec

electical wattage is (pack v * duty %) * motor current = electrical watts

battery current is electrical watts divided by pack voltage

you can calculate the ohmic heating from motor current * motor current * winding resistance = wattage copper loss & ohmic motor heating

wind drag force in newtons is (1÷2) * 1.225 kg/m^3 fluid density of air * estimated frontal area in m^2 * (velocity in meters per second * velocity in meters per second) * estimated drag coefficient = wind drag force in newtons

wind drag power/wattage is wind drag force in newtons * meters per second = wind drag power/wattage

ignored is iron loss, esc loss, battery loss, drivetrain loss, and rolling resistance.

I can tell you one thing is calculated and another then u apply 100A to motor on 8" pneumatic wheels and 20kg board lifts up like its nothing… I am running modified VESC firmware which limits current for low speed as throttle mapping didn’t helped. I am getting kicked off the deck all the time without it.

P.S. I am not using bindings so thats why mostly :smiley: (I mean wheels can lift me ±100kg total without even starting to move)

what’s the kv and gear reduction?

170kv 5:1 big ass tooth geared drivetrain not belts :wink:

looks like about 125lbs peak thrust and 34mph top speed…

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