Battery Wire Gauge
 

Wanting to wire up my new touring car setup with 13.5t motor this weekend. After reading up on other topics etc. decided to go with 14 gauge for the motor and was just going to use the wire that came with the esc for the battery but they aren't long enough as my lipos don't have wires as they have inboard connections. Will 14 gauge be ok for 2s lipo? The wires that came with the esc are 12 gauge and the wires that came with the battery (that are on another car) are also 12 gauge.

You could probably get away with 14 but I wouldn't recommend it. If the esc/motor were to draw excessive amps it could cause problems, even melt or catch wires on fire. Again, amps are the issue here, it really depends how hard you are running your motor, timing/boost, and gearing that will alter how many amps you're drawing at a time. If its all you have and you're in a pinch you could test it and pull the car off early to feel the wire temps.

If 14awg is suitable for wiring the motor, why would it not be suitable for wiring the battery? They will experience similar current levels.

The motor wires only carry current for 2/3 of each revolution due to commutation. The battery wires carry current during the entire revolution.

But I agree that 14AWG should be safe for the battery with a 13.5T.

Exactly, brushless motors are 3 phase motors, hence 3 wires. 2 of 3 are being cycled to turn the rotor which allows them to cool and not carry constant amperage like the battery wires.

Keep an eye on things until you can get proper 12awg

Some additional perspective might be useful in deciding on wire size.

For a Roar Spec 13.5 the four strands in the winding (2 of 21 and 2 of 23) taken together is approximately equivalent to 16 Ga wire. So you are not going to overheat 14 Ga wire that is in the air with the current the 16 Ga wire in the motor can survive.

While I'm not disagreeing with you, 2/3 duty cycle is still the same order of magnitude. I believe we're in agreement that if current levels are enough to overcome the wire rating at the battery end, it's still going to be pushing the limits at the motor end. For that reason I wouldn't recommend using a lower rated motor wire than the battery wire.

With high amp drawing motors such as 4.5T I would agree with you that minimum 12AWG is required, but you can most certainly use 14AWG wire for 13.5T or 10.5T with no problems at all. Ive been running 14AWG wires on my 10.5T with full boost and turbo all year and my car have not spontaneously combust just yet *knocks on wood*

Ended up going into local store today and picking up a metre of 12 gauge.
Thanks for the replies.

I'd always recommend using heavier wire when possible on the battery and motor.

The ratio of resistance between 12AWG and 14AWG is very close to 2/3. So if one were looking to obtain a similar temperature rise on the battery and motor wires, then 12AWG on the battery and 14AWG on the motor would do the trick.

14 will be just fine.