Battery cables 6v vs 12 v Measure the diameter of the cable. This little chart shows the outer diameter (including the insulation) of typical battery cable sizes. This is NOT the diameter of the wire, but the OD of the cable. Battery Cable OD (including insulation) Gauge Outside Diameter 6 .272" 4 .350" 2 .410" 1 .460" 1/0 .510" 2/0 .570" 3/0 .640" 4/0 .699" NOTE: Depending on what "spec" of cable it is, the insulation thickness can vary so these numbers will change. Its just a guide. Using the uninsulated wire diameter is better for wire size ID. This PDF file shows different SAE types: http://prestolitewire.com/filebin/PSA-212007r1%20BatteryCables.pdf You can see that different OD is given for the same gauge cable depending on the insulation type its got. Un-insulated wire diameters are: 0000 (4/0) 0.4600 000 (3/0) 0.4096 00 (2/0) 0.3648 0 (1/0) 0.3249 1 0.2893 2 0.2576 3 0.2294 4 0.2043 6 0.1620 Usually, 12V battery cables are 4 gauge. You would want no smaller than 2 gauge and probably 0 gauge for 6V since the current is 2x in a 6v system compared to 12v. SDC#36133 Jeff Hopman, ND