Nigel Bailey Posted October 26, 2020 Report Posted October 26, 2020 Hi all, I am (very) slowly working my way through a 1948 Aussie-spec Dodge D25. It has the original 6 volt electrics, but at some point has been changed to a negative earth/ground. Why anyone would bother to do this, and yet still retain the 6 volt system, is a bit of a mystery to me. I am going to have to replace the original, 72 year old wiring loom at some point, so the decisions I need to make soon are: stay with 6 volt or change to 12 volt? Positive or Negative ground? I have read the 12V conversion link on the site, but am considering retaining the original 6 volt system(albeit with halogen bulb upgrades). If I do so however, it would seem logical to convert back to the original positive ground-so I would like to know what steps are involved in this? As always, I'm keen to hear the thoughts/collective wisdom from the Forum-I've got an open mind on the whole volts/earthing thing. Thanks! Nigel Bailey Quote
desoto1939 Posted October 26, 2020 Report Posted October 26, 2020 I have owner a 1939 Desoto for the past 32 years and still have the original positive grounded 6 volt system. I see no reason why to convert to 12v. For you basically it is changing the battery cable to be positive grounded and then polarize the generator regulator to be positive grounded. You can use standard modern wire but would suggest that you up the gage to at least 14 gage wireing Rich Hartung Quote
Frank Elder Posted October 26, 2020 Report Posted October 26, 2020 (edited) Halogen bulbs run too hot for our headlight switch.....you will go through switches like candy, LED bulbs run cooler and are brighter. I don't know where you would find LED bulbs for a 6 volt system much less positive ground, LEDS are polarity sensitive so you cannot use just any negative ground bulb. So to me if you stay 6V stock sealed beam, go with 12V if you want brighter head lights. Of course if you want brighter stock head lights ensure your generator is charging correctly and the voltage regulator is adjusted within specs.....properly polarized of course! 00 battery cables and multiple "CLEAN" grounds to the body and frame with stainless steel screws and star washers to "BITE" into the bare metal area that you have already sanded down. Dielectric grease is your friend......it is for keeping your electrical connections from becoming corroded thusly causing more resistance and dim lights, premature generator failure from overload. Good luck in your endeavor. Edited October 26, 2020 by Frank Elder Quote
Frank Elder Posted October 26, 2020 Report Posted October 26, 2020 (edited) 3 hours ago, desoto1939 said: I have owner a 1939 Desoto for the past 32 years and still have the original positive grounded 6 volt system. I see no reason why to convert to 12v. For you basically it is changing the battery cable to be positive grounded and then polarize the generator regulator to be positive grounded. You can use standard modern wire but would suggest that you up the gage to at least 14 gage wireing Rich Hartung If I am going to rewire a 6V system it will get 10 gage wire on everything, that way voltage drop is less and components receive the juice they are entitled to....... Edited October 26, 2020 by Frank Elder 1 Quote
Nigel Bailey Posted October 26, 2020 Author Report Posted October 26, 2020 Thanks for the help gentlemen! Some great tips there and a few things I wasn’t aware of. There is a vintage lighting specialist out here who does 6 volt LED’s, so more investigation beckons. Still leaning towards a properly maintained 6V/positive earth set up at this stage. Quote
Sam Buchanan Posted October 26, 2020 Report Posted October 26, 2020 (edited) If originality isn't your highest priority, but reliability is, a 6v alternator will bring your charging system up-to-date and keep your battery fully charged. A hot battery, even at idle, does wonders for your headlights. ? Here is the vendor I used for my 6v alternator, been very pleased with performance, price and support. This is a one-wire alternator, your ancient and trouble-prone regulator is eliminated. Howard Enterprises While you are at it, install new properly sized battery cables so you can get the full potential (pun?) out of your system. (My wiring as been converted to neg ground.) Edited October 26, 2020 by Sam Buchanan 1 Quote
Nigel Bailey Posted October 26, 2020 Author Report Posted October 26, 2020 Thanks Sam-I believe there are also a number of companies that make ‘generator look’ alternators that have a more traditional style. Certainly minimising the wiring is an attractive proposition. Looks like you’ve got a full flow oil filter there too. Cheers, Nigel Quote
Sam Buchanan Posted October 26, 2020 Report Posted October 26, 2020 1 hour ago, Nigel Bailey said: Thanks Sam-I believe there are also a number of companies that make ‘generator look’ alternators that have a more traditional style. Certainly minimising the wiring is an attractive proposition. Looks like you’ve got a full flow oil filter there too. Cheers, Nigel Filter is a bypass, works the same way as the filters that were originally on our engines. Here is the thread about the installation: https://p15-d24.com/topic/50622-installing-a-spin-on-bypass-oil-filter-photos/?tab=comments#comment-537063 1 Quote
kencombs Posted October 26, 2020 Report Posted October 26, 2020 In my mind the first question is: Is an original look and function the goal of the work? If yes, most of the decisions are really easy, just select parts that make that happen. But, if improved function is more in line with the ultimate goals a whole other can of worms gets opened. Better lighting? Modern radio/sound? Heater need replacing/improving? Maybe air conditioning. All of those are easier and cheaper to accomplish with 12v, negative ground. Of course it can be done other ways, but they add cost and complexity. A 12v neg system can be installed cheaply with read ily available, (even used if the budget demands) parts that can be supported in future at the corner parts place. JMHO 1 Quote
Andydodge Posted October 27, 2020 Report Posted October 27, 2020 17 hours ago, Frank Elder said: Halogen bulbs run too hot for our headlight switch.....you will go through switches like candy, LED bulbs run cooler and are brighter. I don't know where you would find LED bulbs for a 6 volt system much less positive ground, LEDS are polarity sensitive so you cannot use just any negative ground bulb. So to me if you stay 6V stock sealed beam, go with 12V if you want brighter head lights. Of course if you want brighter stock head lights ensure your generator is charging correctly and the voltage regulator is adjusted within specs.....properly polarized of course! 00 battery cables and multiple "CLEAN" grounds to the body and frame with stainless steel screws and star washers to "BITE" into the bare metal area that you have already sanded down. Dielectric grease is your friend......it is for keeping your electrical connections from becoming corroded thusly causing more resistance and dim lights, premature generator failure from overload. Good luck in your endeavor. Frank......I'm not sure what sort of headlight switch your car uses but I've run 12 volts and 100watt H4 halogen headlights thru the original 1940 Dodge headlight switch as well as using the original style floor mounted hi/lo dimmer switch since I converted everything to 12 volts in September 1973 when I installed the 318 Poly without any issue, the headlight circuit does use a relay and the car has been completely rewired and also uses a circuit breaker from a 1968 Plymouth Fury/Oz Dodge Phoenix.......andyd Quote
sidevalvepete Posted October 27, 2020 Report Posted October 27, 2020 If you are keeping the car pretty much as original then there is nothing wrong with 6 volts. It is a simple system. Just follow the original wiring diagram for your vehicle as per the shop manuals. Back in the day some manufacturers used 6 volt and some 12 volt and both were fine. It became problematic when the industry progressed to a point where a lot of the add ons like radios and air conditioning etc began to be manufactured by independent, specialized companies. It became necessary for standardization across the whole automotive industry and they all went to 12 volt neg earth. I rewired my car with a loom from Vintage Wiring Harness in Melbourne. Very well made and works fine, all 6 volt positive earth as per the original. Your choice which way you go but both ways work fine if done properly. Plenty of good help here too to get you there Quote
Nigel Bailey Posted October 27, 2020 Author Report Posted October 27, 2020 Thanks all-really appreciate it. Yep sidevalvepete, will be definitely going to Vintage Wiring Harness for the loom-good to hear you're happy with it. Cheers, Nigel Quote
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