Welding cable size question
 

Hello everyone. A friend of mine has some used welding cable he is willing to sell me at a good price. I am going to use it on my ev project and initially using 72 volt system. He said that it is standard welding cable, but not sure if it is 1/0 or 2/0 cable. Do any of you see any problems with using this cable if it turns out to be 1/0 cable? (his cable is over 100' long now)

Thanks

0 and 00 cable will stand up to some serious amperage.... how much current are you planning on pushing?

Voltage Drop and Cable Size Calculator

The larger the cable size the less voltage drop you will see and the less energy you will waste in the cable.
But there is no way to say what size cable is idea for your vehicle because we don't know the vehicle, the controller or even the batteries!

2/0 should be good for 500+ amps and lead acid golf cart batteries tend to top out at 500 amp peek, but you'd never want to sustain that, of course if your battery pack is split up and you have a few batteries in front and a few in back and a few hidden in some other corner then you could end up with some long wire runs and those you'd want to be larger then what you use for interconnects between batteries, but you also need to look at the total amount of electrical cable that you are using in your battery string.

For most smaller passenger cars I'd say that 1/0 is just fine, you might notice a difference while climbing hills or accelerating.

Well I'm not sure about the current, but I am going to use an open revolt controller, and the batteries are large truck 12 volt batteries grouped together for 72v in the trunk area. I figure approximately 12 feet run to the controller under the hood. My car is a 1983 760 Volvo. I have an electric motor out of a Caterpillar forklift 36/48 volt.

Well if you are getting 100' of cable and you only need to make a 12' run you could always double or triple up on the cable run if you don't think the single run of 1/0 would cut it.

I guess I didn't make my previous post clear, my friend is only going to sell me 40' of cable. two sections of approx 20' (or less) One for Positive, one for negative. Just to clear things up. Thanks Slow S10! Good idea!

Good enough for lead
 

Listing a few assumptions, mostly repeated from the other posts:
- Worst case is that the batteries are connected to the controller with bus bar, and that the cables from the controller to the motor are 20 feet long so the 1/0 motor cables see 500A for the longest time
- 500 amps peak (that's all the ReVolt will put out, right?) on 20 feet of 1/0 is about 2.5V of voltage drop, just over 3%
- The lead batteries won't supply that amount of current for long, so the cables won't be dangerously overheating. They may get warm to the touch!

I would have no concerns with the wire size if it were my project.