6 or 12V

[YLG80]

Optima batteries are lead acid batteries like others.
The main difference is the high cranking peak current that helps a lot when the temperature goes down.(spiral technology)
But the key for all lead acid batteries is shown in that graph.
You are losing almost 20% of cranking capacity when the temperature goes below 0°, or 32°F for you guys.

This a matter of fact.
As you are calling for much more current from the 6V battery, you would have more problems with a low voltage system.
That’s the reason why we are now using 12V and the army 24V.
That is also a good reason why 6V jeep owners needs to properly maintain their vehicle.
It does not forgive if you have even little problems with the wiring, grounding or carburetor.

Yves

[DieFledermaus]

I have a 6v Optima in my '44 MB (10 years now, 11,000 miles) and never had any problems. I did a top-notch resto and used the correct cables and made sure I had very good grounds. Now, I lived in warm California and now cooler Delaware and don't drive when the temps are below 30F. Just my 2 cents.
-Mile

[AWOL43]

Thanks to all for replying so far. To be honest it hasn’t made my choice or decision any easier so far as many points mentioned are all good and as valid as another.

At the moment the GPW was 12 volt with an alternator on it. No starter was present and everything else needs to be replaced as well anyway, wiring, lights, all of it. So I have a clear choice opportunity here to go either way.
The engine will be replaced from a MB engine to a GPW overhauled GPW one.

I tend to favor the idea for a 12V that looks like a 6V as some mention. Like the 12V generator that looks like a 6V one. Where can you get these?

For who asked, I’m just north of Houston, TX.

[tamnalan]

Check with host Ron F or Brent Mullins in TX.

[YLG80]

Thanks to all for replying so far. To be honest it hasn’t made my choice or decision any easier so far as many points mentioned are all good and as valid as another.

At the moment the GPW was 12 volt with an alternator on it. No starter was present and everything else needs to be replaced as well anyway, wiring, lights, all of it. So I have a clear choice opportunity here to go either way.
The engine will be replaced from a MB engine to a GPW overhauled GPW one.

I tend to favor the idea for a 12V that looks like a 6V as some mention. Like the 12V generator that looks like a 6V one. Where can you get these?

For who asked, I’m just north of Houston, TX.

Hello,
If you have not decided yet for 6V or 12V and you have to re-wire you jeep, I would go for a 6V electrical harness.
The lower wire gauge in 6V would allow you to change your mind in the future without any problem.
Yves

[r w devon]

AWOL,

I had my 6V generator re-wound for 12V , a solid state regulator in the original unit , new 6V loom ,and other than the number of cells on the battery, everything looks absolutely correct .
A reasonably expensive option to re-wind the genny, but if getting the engine bay to look ‘correct’ is important , and you don’t want to hope your 6V will reliably charge a 12V system , then there is that option .

Richard

[Nigel]

Hello I would keep it original ,mine works all the time ,you just need a good earth and a good battery , even 12 volts go flat !
And anyway you have a starting handle which should start on first or second time.

[Bangle 99]

A “Gen-er-nator” is expensive. They’re in the $800 range. You can buy a lot of good 6v parts for $800.

What is the SN of the MB engine you’re taking out?


James Teel
Retired Police Sergeant/Bomb Tech
SFC OKARNG
Edmond, Oklahoma
MVPA 30889
'43 Willys MB/ITM jeep
‘42 SS Cars lightweight trailer
<><

[tamnalan]

Ron does not list a 12v generator (that I could find, anyway and I didn't call) but he does have, in stock, a 12v JMP regulator and a 12v starter that should fit a G503. Not cheap, but not $800. I don't think a 12v generator should be too hard to find, but it might not look correct.

My 6v system never lets me down when I pay attention. If I neglect my MB for a year as I just did then it exacts revenge, as in a stuck intake valve and a disappointing starting system. IMHO, 6v systems under regular usage will perform just fine unless it's "Whynot Minot" cold (for us USAF guys), in which case a guy then simply ties the jeep up with 'lectricity rope', as my Dad used to say. He'd stick an incandescent light bulb down near the oil pan overnight and our stock 6v cj3a would reliably start most any cold morning in the central Montana winters I grew up in.

[sjalbert]

Thanks to all for replying so far. To be honest it hasn’t made my choice or decision any easier so far as many points mentioned are all good and as valid as another.

At the moment the GPW was 12 volt with an alternator on it. No starter was present and everything else needs to be replaced as well anyway, wiring, lights, all of it. So I have a clear choice opportunity here to go either way.
The engine will be replaced from a MB engine to a GPW overhauled GPW one.

I tend to favor the idea for a 12V that looks like a 6V as some mention. Like the 12V generator that looks like a 6V one. Where can you get these?

For who asked, I’m just north of Houston, TX.

Hello,
If you have not decided yet for 6V or 12V and you have to re-wire you jeep, I would go for a 6V electrical harness.
The lower wire gauge in 6V would allow you to change your mind in the future without any problem.
Yves

Heartily concur. 6v uses a thicker wire. Cost difference is minimal.

[AWOL43]

6V harness looks like a good idea regardless. Thanks. It might just happen that the Jeep sits for longer periods as they sometimes do. I have a MB that was already 12V and always fires up. If it’s after a week or half a year or anything. So from that perspective a 12V would be good and more hassle free. Tend to still favor a 12V system that looks like a 6V. I’ll try and see if I can find the parts for that and take it from there.

For who asked the engine that comes out of the Jeep is a very early MB SN. Slat grill range. Which was surprising to find out to be in there.
It won’t be for sale. Will shelf it as a back up for my MB, which actually runs with a wartime generator motor. That runs just fine at the moment so won’t touch that for now.
Transmission is a T90 and that will be for sale as I have no need for that.

[Klaas]

When I reconditioned GPW17331 it already was 12V, only the components were not "the right ones", so I fitted a brand new 12V starter (ready available as repro), a regulator with solid state electronic internals but still in an original casing (there is info about them in another thread here: viewtopic.php?f=25&t=244474) and an original 6V generator that was converted to 12V by a local electrical auto engineering firm. Everything under the bonnet looks original except for the battery, but I am OK with that. Four years and about 4000 miles onwards still all functioning without issues. Taking the GPW out to stretch its limbs most weeks, but can be longer depending on weather.

The only other components to replace are all light bulbs and the fuel gauge (or fit a 6-12V converter inline to the gauge).
Oh and I sometimes connect a SatNav for the longer journeys...no issue with 12V.

My previous G503 in the late 70-s was 6V....nothing but trouble but age and condition of the components might have something to do with that . Much easier to get correct parts nowadays.
Go 12V for peace of mind.

[sjalbert]

...
The only other components to replace are all light bulbs and the fuel gauge (or fit a 6-12V converter inline to the gauge).
Oh and I sometimes connect a SatNav for the longer journeys...no issue with 12V.

My previous G503 in the late 70-s was 6V....nothing but trouble but age and condition of the components might have something to do with that . Much easier to get correct parts nowadays.
...

Klaas I think you meant a 12-6v converter inline to the fuel gauge. I installed a 6-12v converter in the glove box to keep my cell phone charged up when I'm using it for navigation.

Age & condition make a huge difference with electrical components. I had my generator and regulator rebuilt last spring ahead of the Santa Fe Convoy and cleaned up all of my grounds and had no electrical issues with my 6 volt system during the 10 day drive.

[Austin F]

Hello fellow Jeepers!
Now I am not at all an experienced "jeep-man", just joining and all, (hence my rank), but Greendot 319 has a good youtube video on his channel arguing for a 6v setup, and showing how it works as follows:

https://www.youtube.com/watch?v=DvHiR_2h328

He goes into the basics of wiring and all, wich you all here are probably good at (excluding me) , but I found the video to be very informative and easy to understand.

Hope this helps with decision making!

[17thAirborne]

I’m in central Oklahoma, where it gets both super cold and super hot. My jeep was 12v when I bought it. Since I’m somewhat of a purest, I converted it all back to 6v. I’ve never had a problem, other than when my repro foot start switch went bad or when my filterette was shorting out my system and draining the battery.

Here’s how your 6v system should work.

https://youtu.be/mo_5cNLqh0A



James Teel
Retired Police Sergeant/Bomb Tech
SFC OKARNG
Edmond, Oklahoma
MVPA 30889
'43 Willys MB/ITM jeep
‘42 SS Cars lightweight trailer
<><

That's a super restoration. Runs great.