Hello everyone...this is just the second time I've posted a question...so here goes...what gauge do you use for a battery cable if the battery is 10 ft from the starter...a'32 Victoria with the battery inside in the rear. AND, how long should the negative battery cable be?...I've read the neg cable should be as long as the positive...why?...thanks for your time on this...Jim
I use a 4ga in my T and it's about 3' from the battery. For 10', I'd run a 2ga. I think the further, the thicker.
With my trunk mount battery I use #2 copper from the battery positive to the starter (about a 10 foot run), #2 copper from the battery negative to the frame at the rear of the car (2-3 foot run), # 2 copper from the front frame to the engine block (2 foot run). I also have a smaller woven ground strap from the body to the frame. Car starts like it has two batteries, quick and easy and no charging issues. Larger diameter cables can handle more current so the further away the battery is the larger the cable needed. I use the chassis as a ground path so no need for a full length ground cable.
yes, the thicker the better for longer than normal runs. i like to use welding cable because of the finer strands. as for neg. needing to be as long as pos? i've never heard of that one. my ground cable are about 18" long to the frame in the trunk, then in the front frame to block with another shorty. i solder the joints, and then use industrial heat shrink tubing.
Ask these guys their recommendation - they make and sell custom cables for a living.... I bet they say their heaviest gage 4/0......... They have made several cables for me..... excellent workmanship and service..... Use the vlotage drop calculator on their site - you will see right away why you want 4/0.... http://shop.genuinedealz.com/ http://www.ebay.com/itm/Inverter-Ba..._Accessories_Gear&hash=item45f1e7a5c8&vxp=mtr
The negative battery cable doesn't have to be the same length, but it should be the same size (gauge). I ran a smaller size ground from the engine to the frame on my 50 Chevy and couldn't figure out why it didn't want to turn over very good. By accident, I touched the smaller wire. It was very hot. It was at that time I had my DUH moment, realizing I should have used the same size wire. Change wire, start easy. Live and learn!
yes , the thicker the better...i usually use 2 gauge for the ground cable i rum it right to the engine block,not the frame. then two ground straps from that same spot on the block..one to the body and the other to the frame
I think the important limit is voltage drop in the cable(s) when BIG amps are needed for starting, especially starting in cold weather. More normal circuits with possible constant load may be limited by long term temperature rise of the wire itself. This link to a Car Craft article lists a typical starter circuit drop or 0.1 > 0.2 volts when cranking. http://www.carcraft.com/howto/116_0507_top_10_electrical_fixes/viewall.html Here's a cable sizing calculator based on amps. http://www.colemanair.us/vp_asp/Scripts/Articles/TheBasicsAndBeyond5_WireSize.htm ( I put in 200 amps, 10 feet one way, and 2% voltage drop which would be 0.24 drop in a 12 v application - it says Use a wire size of 4/0 AWG to prevent a voltage drop of more than 0.24 Volts (2%)). I've seen 20 below here in Massachusetts, so I usually put on the biggest pre-made cables I can buy for front mounted batteries. If I could get a nice low voltage drop when cranking using short ground cables connected to the frame I wouldn't buy a full length ground cable.
2/0 is more than adequate to handle up to 250 amps under 14" according to the guidelines that I have used for years. In actuality even 1/0 will do the job providing it isn't some real high compression motor with starting issues. As for the ground, as with any cable, the shorter the better (less resistance) and use the same diameter.
The Jalopy Journal
