TheSamba.com :: View topic - 6Volt Battery cable vs. 12Volt battery cable

Fri Apr 20, 2018 8:34 am

A little unknown fact about battery cables is that there is a size difference between 6volt and 12 volt cables. 12 volt cables are smaller in diameter due to the fact that electricity is more efficient at higher voltages, and therefore less cable surface area is needed to transmit the same.about of power (Watts).

Because of this, you can run a 6 volt cable on a 12 volt system, but you won't be able to run a 12 volt cable on a 6 volt system without experiencing sluggish starting problems, especially when warm or hot.

Most people aren't aware of this difference, and will gladly sell you a 12 volt cable for a 6 volt application.

So with all that being said, I have a few questions.

1. What is the proper Gage size for a 6 volt vw starter cable?

2. What company sells a 6 volt starter cable in the correct size?

Thanks! - wheelie pete

Fri Apr 20, 2018 9:15 am

Yes half the volts = twice the current.

The correct wire gauge is shown on the wiring diagrams.

From the 1962 wiring diagram, the wire gauge between battery + terminal and solenoid terminal 30 is 25 square millimeters.

You can find online converters to convert square millimeters to American Wire Gauge (AWG). 25 sq. mm converts to roughly 3 AWG. 4 AWG is a little bit smaller than 25 sq. mm so to be conservative you'd want to go for the larger wire size in AWG, which would be 3.

Fri Apr 20, 2018 9:57 am

sjbartnik wrote:
You can find online converters to convert square millimeters to American Wire Gauge (AWG). 25 sq. mm converts to roughly 3 AWG.

At the very bottom of each wiring chart web page is a conversion chart and other good to know about info.

Fri Apr 20, 2018 9:58 am

Well, color me one of the uninformed. I'm now going to be changing my cables. Thank you for the info.

Fri Apr 20, 2018 10:09 am

I make my own out of #4 welding cable. Far more conductive than any $20 cable from a FLAPS

brad

Fri Apr 20, 2018 12:18 pm

Battery cables are at least 50% oversized, so you wont see any difference using a 12V cable on 6V

Fri Apr 20, 2018 12:29 pm

I had our Heavy truck repair shop make me ones out of 2 ga cable. I also ran an extra one from the Batt - right to a starter bolt. I cranks Awesome Now!!!
Roger

Fri Apr 20, 2018 12:44 pm

I'm using the positive cable from WW for my 6V system (1964 Beetle).

The thing I couldn't figure out when pulling it through the pan grommet is why in the world the grommet I.D. is so small. I ended up tearing the very end of the grommet off. It is definitely sealed, although it doesn't look as good now.

Fri Apr 20, 2018 2:02 pm

Thanks for the replies!

The 66 bug diagram (6 volt)- the starter cable specified is 25. (66-69 Bentley)

The 72 bug diagram (12 volt) - the starter cable specified is 25. (70-79 Bentley)

The Karmann Ghia diagram (66-69 Bentley) (12 volt) - the starter cable specified is 35.

The Karmann Ghia diagram (70-79 Bentley) (12 volt), the starter cable specified is 25.

I don't know why there is a discrepancy between the 12 volt ghia cables, unless the 35 is left over from the 6 volt ghia. I just do not know. However, I believe the ghia has a longer run than a bug, so a bigger cable makes sense.

4 gage = 21.2 mm^2

3 gage = 26.7mm^2

2 gage is 33.6mm^2

1 gage is 42.4mm^2

Sjbartnik covered it earlier, you really want 3 gage or bigger for 6 volt, and perhaps 2 gage for an early 6volt ghia. It appears you want 3 gage for 12 volt also.

I checked with Wolfsburg West this a.m., and asked them about the gage on the their "6V" starter cable, and they stated 4 gage. That is definitely the wrong size.

Hope this helps!

Fri Apr 20, 2018 3:53 pm

In that case, I’ll be following along to source the correct size cable for 6V Beetle.

Fri Apr 20, 2018 7:52 pm

Bigger is better in this case. I worked on a 37 Chevy with 4 gauge auto parts store cables, and it had extreme difficulty turning over when hot. A fellow enthusiast up the road with pre-50 chevys suggested to make cables out of 1/0 welding cable, and it would turn over like a modern car. After getting the cables made, it spun over three times the speed of the 4 gauge cable. Do you need 1/0 cables for a Beetle, probably not. I would look into 2-4 gauge welding wire though.

Fri Apr 20, 2018 8:40 pm

Not only is thw size important, but also the size of the conductive strands inside the cable. Cheaper cabkes have fewer strands per given cable size. This is what makes welding cable such a good conductor. . On my buggy the battery sits over the front beam. I have #4 welding cable from the battery going to the + terminal on the starter AND another one on the top starter bolt. I use a very small 320cca battery and i can strart my high compression engine even when hot.

brad

Sat Apr 21, 2018 6:05 am

I see people discussing getting cables made. Is there a company out there that does this or is this something that is typically available locally?

Sat Apr 21, 2018 6:33 am

Go to your local Heavy truck repair place.
Just measure them & tell them what you want on the ends. I had my + cable made red & the - is black. Measure the size of the bolt you want the other end to go on & tell them.
The place that done mine soldered everything together & covered the ends with shrink wrap. I used 2 ga from our local heavy truck repair place & ran the - right to the bolt for the starter. I also had them make a short piece to go from the trans to the body They made them while I waited. Took like 15 mins. . Hope this helps.

Roger

Sat Apr 21, 2018 8:35 am

Sharp64 wrote: I see people discussing getting cables made. Is there a company out there that does this or is this something that is typically available locally?

Weld supply stores may be a good source for cables. they maybe able to crimp the end you need for you

Bug On!

Sun Apr 22, 2018 7:49 am

Yeah, heavy truck places, welding supply stores, and shops specializing in batteries should be able to fix you up. There are various listings for 5-10 ft. lengths of welding cable in black/red on eBay, and Summit Racing has various crimpable, and solderable battery/eyelet terminals for the ends for the diy.

Mon Apr 23, 2018 7:01 pm

This implies a necessary change to the braided ground strap (wire) as well.

Hmmm.

Mon Apr 23, 2018 7:55 pm

Did anyone mention that with higher voltage, lower current is needed for equivalent electrical function. So 12V systems are OK with thinner wires....