Electrical wire confusion

[pmccarthy]

I want to rewire my truck project and decided that 10-gauge wire was what I needed for 6 volts. 10 gauge is somewhere between 2.6 and 3.2 mm diameter depending on which reference you believe. Found some at my local auto supplier but it seemed too thin, much too thin. Further investigation reveals that auto wire sold in small reels in auto suppliers is labelled according to the outside diameter of the plastic insulation. Go figure! Luckily I didn't buy it.

Edited January 25, 2023 by pmccarthy

[onetrack]

Why wire the truck for 6 volts? Most people rewire old vehicles for 12 volts - you get better starting, better lighting, and a more-readily available range of parts.

[pmccarthy]

Because it is a restoration and because I have a good generator. But it is not an easy decision.

[ClintonB]

No 6 B and S cable was 16mm2 when I started using for caravan fridges. Now 14.59mm2 and the lugs have gone down in gauge of copper tube wall thickness, now $400 crimpers I bought 16 years ago don’t crimp up tight and I have to go down 1 setting to lock ends on, then they end up with wings on side. Always go up a size now rather than down and there is less chance of overheating of copper/or failure to carry load. 

[facthunter]

Not so easy with some of the setups to change from the original . The biggest change is from generator to an alternator to get the charge at lower revs but many are gear driven and everything's made of nice cast iron that's already lasted for nearly 100 years.. No  replacement will do that. Put relays on you lights High beam at least.   Nev 

[onetrack]

It's not that hard to dig up a 12V generator so there's no real need to fit an alternator - which grates against period correctness. The old Chevy uses a belt-driven generator, so no real problems there.

 

Trying to source 6V of anything today is a PIA, and it usually costs a fortune. Having said that, I think I've got a new 6V regulator in my collection of NOS stuff.

 

The other thing is, that doubling the voltage halves the amperage, so you can use thinner wiring. But the two greatest reasons for using 12V is faster cranking and a hotter spark that is less affected by current draw.

 

Who remembers the old 6V Customlines of the early 1950's, and their piss-weak starting? - particularly when hot.

 

It was usually a case of hold your breath and hope they started, with their wheezy old starters going, "R-R-R-R .... R-R ... R-R-R-R-R-R ..... R-R .... R ..... R-R-R-R-R....."

[pmccarthy]

I had a 6v VW with a vibrator radio. Good fun at the time.

[onetrack]

When I was dozing contracting, and much, much younger - about 1967 - I had a farmer client, Herb Watkins - who was a classic "old bushie". His workshop was a bush-timber-framed shed, and his welder was a fabricated trailer-mounted rig with an old 6V Customline V8 coupled up with pulleys to a Lincoln 250 BT welder.

The brother and I broke something on the old Allis-Chalmers dozer we had back then, and Herb offered to weld it up. To give you an idea of Herbs setup, his acetylene gas supply was one big steel drum inverted inside another, and water in the bottom drum - with chunks of calcium carbide thrown into the water regularly, to generate the necessary acetylene gas!

 

So, he goes to start the old Cusso ... and in the best 6V Ford fashion, she goes, "R-R ... R-R-R ... R-R .... R .... R ... R .... R-R ........." .... and old Herb promptly gets very exasperated with its hard-starting issues. 

So he says, "I'll make ya start, ya bastard!!" .. and he whips out a pair of heavy jumper leads ... hooks them up to the nearby row of 32V lighting plant batteries .. and promptly drops the leads onto the old Ford 6V starter!!

 

Well, I tell you what - that old Ford V8 didn't know what hit it, as that starter spun at about 3 times warp speed, with a shrill screech - and the old flathead jumped into life, like nothing I've ever seen!

And I reckon old Herb had pulled that stunt more than once, too, such was his familiarity with the process.

 

The thing with 6V starters, they will still perform quite well on 12V, as long as you don't crank them for an excessive period. But you do need a 12V solenoid, the 6V solenoids can't handle 12V.

 

https://www.jalopyjournal.com/forum/threads/running-12-volts-through-a-6-volt-starter.402740/

[facthunter]

The starting problem is often because the starter drops the voltage of the system down to about 4 volts  remaining for the ignition. A special coil and a shunt  resistor thats cut out of the circuit when starter activated fixes that as long as you don't rest your arm on the resistor accidently.. because it's hot. Some vehicles like a Bull nosed Morris Cowley have the generator as a starter and always connected. In electric start Indian was available in 1914 where the starter doubled as a generator. Some later Japanese motor bikes did it also..   Nev

[spacesailor]

AND 

12 volt starters can be wire to 24 volt just for emergency starting! .

Thats two Not so full 12 volt batteries. Full  charge is almost 14 volts each .

spacesailor

[facthunter]

Starters are a very low resistance jigger and will drop the voltage of any crook battery fast and an undersized one also. CCA is what counts. Cold Cranking Amps.  This is what's happening when the starter solenoid chatters.  A fully charged 12 volt lead acid battery should register 14.2 volts on no load. Nev

[spacesailor]

My solar panels are set to 13.8 volts max charge .

spacesailor

[Old Koreelah]

10 hours ago, facthunter said:

…In electric start Indian was available in 1914 where the starter doubled as a generator. Some later Japanese motor bikes did it also..   Nev

I believe several post war French cars also combined the two. Modern Hybrid cars could surely use the ruddy great electric motor as a starter.

[onetrack]

I used to own a Magirus-Deutz Jupiter truck (air-cooled V8 diesel of 195HP) - which had an amazing setup of a 24V starter and 12V lighting and gauges!

 

Everything basically ran off 12V - but when you hit the big semi-rotary starter lever (the lever operated through about a 90° arc), this actuated a big solenoid that coupled up the two batteries, to provide 24V, just to the starter!

 

It was a surprisingly trouble-free system, despite its complexity.

[old man emu]

On 25/01/2023 at 8:25 PM, pmccarthy said:

I had a 6v VW with a vibrator radio. 

I bet that radio was stimulating.

 

[nomadpete]

Those vibrators were not popular. Some users found the high voltages produced were quite uncomfortable.

[Marty_d]

For a good laugh (and very surprisingly, based on a true story) watch the movie "Hysteria".

[onetrack]

Is it just some coincidence that the cinematography of the "Hysteria" film was done by a gent named Bobbitt??

[pmccarthy]

How would he react each time the  director called 'cut' ?

[Bruce Tuncks]

The only time my P76 car didn't start it was because the ballast resistor had failed. As Nev said, the car generally sucks the start volts down and so the coil is sized at this low voltage and not the 12 volts. Once the engine starts, the ballast resistor cuts in to protect the coil from the 12 volts.

SO, if the engine catches but stops as soon as you stop cranking, it's the ballast resistor.