I used the current and resistance of the battery to calculate power loss in battery. So the power loss in the batteries are correct.
Where I was lazy and I’ll admit it, I never actually calculated the correct cell drop and so on the conservative side gave 3.6 (12S) and 3.8 (10S) as the cell voltages.
In reality the correct cell voltages are 3.72 and 3.77 respectively. The 12S still wins…
I tried calculating, there’s some weird math going on, is this all from theory or from measured values?
If measured then i’d be interested to see how you replicate the exact same conditions to get up on foil, and the curves you get the voltage and current data from.
The current values are real world max values at takeoff and during powered up carving.
Batteries all start at full voltage. Technique used is the same, pull trigger, throttle curves all the same and only stand up once the board has shot out the hole and on the plane. It’s by far the most efficient way to get up as weight distribution is optimised.
From the real world current you can then calculate the rest of the power losses through battery etc and total power used etc…
I would like to use some calculator that could help us compare, given the same prop and motor, different voltages, also giving the motor phase current, as that is a killer of esc and phase wires on overloaded setups.
I think the root cause is the current data. Something in data is mixed from different sources. Either battery voltage was not the same, prop not the same or conditions not the same. You could upload the logs to clarify, pretty sure there’ll be something there.
Na, its just the rounding on the voltage drop on the for 10S pack… If I remove the rounding then it adds the extra 2.666667W that you see at Pbatt effective:
What i mean is that the theoretic voltage we defined at 4.2V and the current of 60/80A probably don’t match and therefore the results get skewed. Or there was a different load somehow
Reason i think this is that to perform the same task with the same motor and prop would require the same mechanical power, logically since the load is the same (drag at lift speed)
Where would the 340w, 13% efficiency loss then be? It’s not likely in the motor losses (resistance, eddy currents, friction) since the motor has to perform same task.
That leaves two basic options, losses inside the esc or losses from worse motor control.
Inside the esc and it’s resistance losses? It is too large, 340W is a huge heating in relation to the currents and resistance in the esc.
Motor control? It’s only 20% more voltage, switching frequency is the same. To actually be a loss means the applied current needs to reach the coils at the wrong time vs the rotor position or are spiking out of control. Spiking would be more likely at higher voltages, right? (=advantage 10s system)
You require the same thrust at the prop at different battery sizes in order to achieve
board plane speed or foil stall speed. But with different voltages that comes at different battery power.
eg…
Say I was to ride using the same power of 3018kw in both systems. That means with all the voltage drops etc I see the following (with a 3D printed prop I have assumed a lower efficiency):
The noload rpm will be higher on 12s but loaded rpm can’t be calculated and used like you propose since the motor might not be capable of reaching a higher rpm. This is due to the need for increased torque, current and power at higher rpm. Scaling down from a higher rpm is equivalent of reducing the duty cycle and that is already accounted for in the difference in battery current.
Looking forward to some data on the behaviour. With logs!
Hello, in order to get more info and understand more props things I got ecalc membership, allows to check for partial throttle. 8S3P at 72% duty cycle/Trottle 2600RPM is exactly equivalent to 12S2P at 48% duty cycle and 2600 RPM. same efficiency from the motor. 12S allows much higher max power.
phase currents are not calculated by the tool.
My Maytech hand controller stopped communicating with the Maytech VESC. After reading some posts, I know other ones are better. But, is there a way to fix my problem with this one? It’s been working great until yesterday.
It started losing signal occasionally.Then it would just go without any trigger–even with the controller off! I held the board on its side until it finally stopped. I finished off the battery without anything else crazy and came home. I hooked it up to the computer, and the controller side of the ESC is not working right. I tried resetting it but now it does nothing when I pull the trigger. I reset the firmware, the motor, and the controller. No go. I’ve attached some pictures.
