2 vs 4 gauge cable

[sleepyluke]

Figured this question was better on its own. I know there a re a couple of threads that talk about this in a few places of varrying age. I am currently not looking to build a monster cart, but looking to swap cables and motor and possibly controller. I am not looking for a 35 mph cart, but would like it to keep speed when climbing hills, climb hills with 2 people that it currntly stops woth 2, but will make it with one kind of thing. I don't care about burn outs, but would not mind throwing a little gravel.... I am still an overgrown redneck 4 year old after all!!

When plaing with Ohms law calculations, I seem to find that there really is minimal loss when swapping cables (even from 6 gauge down to 2), but also understand the better flow and keeping cooler and wire ratings go into that as well (artery idea/theory). My assumption is if 4 is better than stock, why not just go ahead and swap to the 2 gauge wire? I am cheap, but the cost for upgrading is minimal if you do it once, and don't want to and probably won't do it to 4 gauge and then to 2 gauge.

If my calculations are correct, with 36 volts and 300 amps and 24 feet of cable, power loss with 6 gauge wire is 1.06 volts, 117 watts, or 1.09%.

Same parameters, 2 gauge - loss is .23 volts, 14.51 watts, and .13%.

Now when looking at then against each other, of course the 2 gauge wins, but even with the 6 gauge, you are getting 99% power to the motor, and I can gain or lsoe enough weight in a weekend for 1%.

Strictly numbers wise, it sitll makes sense, but not as much as I thought. Does it come down to the basic ratings of the cable?

Thanks for reading through my rambling and helping all of us out

[scottyb]

No wonder they call you sleepyLuke, it sounds like you have been loosing sleep over this 1%
The controller design engineers say 4 g is good for 400a and smaller controls. 2g is needed for 500a and bigger controls.
If you run on 48v you use less amperage so 4g can work for a 500a on 48v, The costs are not great in material and everything including the lugs are heavier which means greater amperage delivery and a longer useful life. You are saving money doing it yourself. Spend some of that on larger conductor, you won't be regretting it..... and you'll sleep better

[sleepyluke]

Honestly I do think about stuff too much but this one is more of I know enough to be dangerous but not enough to get it done right!

[scottyb]

I think all of the golf cart engineers and motor builders agree that 2g is enough for most builds... some swear it is more than needed....