2/0 AWG max current?

[n1866878]

Hey,

I was just wondering. I'm planning on using 2/0 AWG (70mm2) wire for my electric system to carrying 100A continious and 300A for 30 seconds and I'm planning on using a 400A fuse.

I just want to make sure the wire won't melt before causing the fuse to blow. Is 2/0 AWG adequete for this job?

 

[Alan B]

What temperature rated insulation are you using? What cable type?

What battery is delivering 300A?

You might be better off having one thread for your build description and all your questions, instead of scattering this all across the forum. Context is important, and it is lost this way.

 

[n1866878]

https://www.ebay.com/itm/70mm2-Black-Red-485-A-Amps-Flexible-PVC-Battery-Welding-Cable-FREE-LUG-PER-METRE/192371163817

We're using a bunch of 18650 cells.

 

[Punx0r]

00 AWG is going to be completely overkill - it's good for nearly 300A continuous: http://www.powerstream.com/Wire_Size.htm ("chassis wiring" is the closest to a vehicle/ebike application).

Personally I'd be looking at something like 4 AWG and I'm sure there's more than a few people who would use 8 AWG...

 

[n1866878]

I actually need it for another project too, so that's why we were going for it.

 

[Punx0r]

Ok, well the fusing current for 00 AWG is approx 2700A, so you should be very much ok with a 300 or 400A fuse in the circuit...

http://www.powerstream.com/wire-fusing-currents.htm

 

[n1866878]

Thanks for the reply. This may be a stupid question but.. Here i go anyways.
If the motor is designed to run at 100A continious and 300A for 300A for 30 seconds, will using a 400A fuse not mean that if something goes wrong(motor draws more current for some reason?) a current of up to 400A could go to the motor without blowing the fuse. Wouldn't that damage the motor?

 

[Punx0r]

As touched on in the other thread the fuse is really intended to prevent fire in case of a short circuit, not to protect the motor.

Motors take brief overloads very well and depending on what your controller will permit, very high surges can be quite normal. E.g. When accelerating from a standstill.

The limitation of a motor is heat, so it needs a combination of cooling and restricting how much current you give it. It's not practical to do this with a fuse. Controller current limiting can be used, but it's a blunt instrument, unnecessarily restricting motor in some circumstances while still making it possible to cook it in others. A temperature sensor in the motor and either using automatic thermal rollback via the controller or a cycle analyst is much better. Or have a temperature gauge and do it manually with your foot. Or better yet, size the motor for the application so you never exceed its capabilities!