Hi, I’ve recently finalized my bill of materials and was wondering if anyone could help me understand the electronics assembly part. I’m specifically concerned with the high voltage and current ratings of the ESC and motor, but I’ve seen a few people mention that they don’t run at their full capacity. Is this true?
I’m planning on getting these parts
Battery (2 wired in series)
I will end up with a 44.4 volt battery capable of 20 amp hours. The ESC is rated at 14 to 75 volts at 200 amps continuous, or 300 amps maximum. The motor has a range of 25 to 84 volts with a peak current of 200 amps.
The amp rating for the ESC and motor seem high, so I wanted to confirm I won’t actually have that much current in the ESC and motor. Lastly, how should I identify the size breaker I should use between the battery and the ESC? Is it simply multiplying the battery’s C rating by its Ah to get the amperage of the breaker, and using the battery’s rated voltage for the breaker as well?
All information is appreciated!
Depends on your setup, wing, board volume weight, propeller and conditions. These components fit together and max current for takeoff will be somewhere between 70 and 120A battery current. The max current of the vesc is the motor current which will be roughly 1.5 times battery current. Have a look at metr logs, people shared in this forum, there you can see these values. For the breaker better just use a fuse (200A) and anti spark plugs to connect the batteries. If you use a fuse switch or relay, don’t switch it on under load, you need an anti spark circuit to preload the caps of the vesc before you close it, otherwise it won’t last long.
Fuse: IMAXX MDP200: KFZ-Sicherung, midiOTO, 200 A, 58 V, violett bei reichelt elektronik
IMAXX HMD1: KFZ-Sicherungshalter, midiOTO, 200 A, 58 V, Schraubanschluss bei reichelt elektronik
As currents are high, most people use AWG8 cables. For connectors, AS150 or other high current connectors should be used.
Thank you for the help. I’d just like to restate what you said to confirm everything. I will connect my battery to the ESC using AS150 anti-spark connectors, and run the positive wire through a 200 amp fuse (or circuit breaker, but probably fuse). Should I connect the positive end or negative end of the battery first? What does it mean to preload the caps of the vesc? Does that mean I am completing the circuit by connecting the anti-spark connectors on a battery? Also, if I were to get a circuit breaker instead of a fuse, I would need to ensure I reset the fuse before connecting the battery, right? (are there anti-spark fuses?)
Thank you for all the help.
Preload means connect it through a resistor so the the caps get charged at a lower current over a couple of seconds. If you connect the vesc to + over a 500 ohm resistor, a 2000 uF cap will be fully loaded after 5s with 50V battery voltage, see here: https://www.allaboutcircuits.com/tools/capacitor-Charge-and-time-constant-calculator/
An anti spark connector does the same thing (faster).
So if you use a fuse with a switch, close it and then connect the vesc with the anti spark connector afterwards. If you use separate connectors for + and - like as150, the as resistor is only in one connector, normally +, connect this connector last.
Thank you so much for the help. I have one last question, if you don’t mind. You mentioned a 200 amp fuse, but I don’t see anything about voltage. I believe I can just go a little higher than the voltage of my battery, right? So for a 44 volt battery, I could get a 48 volt breaker?
Yes if the fuse voltage is rated higher than your battery voltage it is ok, the one I use is rated 58V. The rating is because in case the fuse brakes, it needs to be able to extinguish the arc to interrupt the current.