Correct sizing for Battery cables

Avondale · Jul 7, 2016

My old C I/H 574 (circa 1972), has had wiring work done by previous owner(s). I have the wiring dia but do not see the correct cable sizing for the main battery cables, (both +ve and -ve). In fact, my machine has two different size cables. The +ve is 0.549 with insulation and 0.483 on the bare strands. The -ve is 0.503 with insulation and 0.307 on the bare strands. I am not sure if this is what was original or if what was available. Can anyone offer up an informed opinion on what the correct AWG size should be for this 52HP Diesel?

Thank You in advance for any help provided.

LD1 · Jul 7, 2016

Sounds like 4/0 wire on your positive and either 1/0 or 1 GA on the ground. Your number for diameter is right between those two.

Should be heavy enough. I have never seen any real hard and fast rule for bat cable sizing. Because it is such an intermittent load. Ampacitys of wire are based on how hot they can get without toasting the insulation. Which is why insulation type, and weather the wire is in open air, stuffed into a conduit, etc all effect the rating.

Your battery is probably capable of 800-1000 amps. But you don't need wire rated to that for such short duration.

Most cars use small 6ga wire. Trucks maybe 2-4 GA.

But In General, no such thing as going too big. I rewired my backhoe with 3/0 welder cable.

JerryK · Jul 7, 2016

Put big enough wire on it and you won't have to use loaded tires or wheel weights...... [[

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George2615 · Jul 7, 2016

I'm not familiar with your 574. Does it have a 6 or 12 Volt electrical system.
6V systems usually have heavier gauge cables than 12V systems.
If it was a 6V system converted to 12V the heavier cables will be fine.
If it is a 6V system with smaller diameter cables they may have been replaced by the prev. owner with smaller diameter cable used on 12V systems and not be large enough to handle the current.
I have an antique truck that came with a 6V system and your cable sizes are very similar to mine (.540 w/ins, .480 bare).
My ground cable is flat braided and not round. Whether you have a 6 or 12V system the size you have should be fine unless there is corrosion of the copper under the insulating jacket. I have seen cables that look good but when the jacket insulation was cut back the wire was corroded.
If in doubt you can buy cable at your local welding supply house and install new ends.