For a project I'm using 4 12V, 35AH lead acid batteries in series which powers a 400W, 48V bldc motor. The maximum current the motor would draw from the battery set is 12A. enter image description here

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How should I choose the type and rating of wires that connects the 4 batteries in series?

How should I choose the type and rating of wires that connect the battery to the motor unit?( I haven't arrived at the length of these wires yet)

I also have to provide a kill switch for the circuit. How do I choose that?

This is how the motor control unit is : enter image description here


1st find out the DCR of the motor coil and plan on support these currents at max voltage. Then choose switches with much lower resistance than this for low heat loss. Normally starting current max is 8x rated max current! +/- 25% depending on motor and controller design.

Brushless DC motor problems at high velocities

  • \$\begingroup\$ Thanks. Any idea on the connecting wires? \$\endgroup\$ – asr Sep 19 '17 at 4:56
  • \$\begingroup\$ yes of course , use Ohm's Law for voltage drop and wire heating based on 100A surges during acceleration from start and consider welding cables.. Look at golf cart design. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Sep 19 '17 at 14:16
  • \$\begingroup\$ for short distances smaller AWG is ok, like here ebay.ca/itm/… \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Sep 19 '17 at 14:26

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