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6v Versus 12v Electrics


likaleica

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Hi again guys

Hope I'm not guilty of posting too many questions on here - I'm a newbie 1939 Plymouth owner with quite a few issues to sort on the car!

One immediate problem is that tho the whole car has been rewired, the original two stage pull switch for the headlamps and sidelamps has failed. I can get something similar here in the UK - but rated at 12v - 24v. As my car is 6v,  is it OK to use this switch?  Is it possible to ream out the original switch knob (made of an early plastic such as Bakelite I think) to fit the larger spindle of the replacement switch - or would I be better having the new spindle lathed down to the profile of the original?

Longer term I'm wondering if it's wise to convert to 12v negative earth - as I was advised by a guy with a 36 Olds who'd done this.  He uses voltage reducers on original 6v equipment such as gauges etc. But another very experienced enthusiast I spoke to said don't do it. I'd be grateful for any advice on this too,  please. Thanks guys

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When you say the headlight switch has failed are you sure you are getting power to the switch? Have you checked it for power with a meter? Is there possibly a fuse located somewhere that has failed?

 

Using a 12 volt switch on 6 volts is not a good idea as the current draw on 6 volts is twice that of 12 volts and the internal contacts would most likely fail.

 

If you do indeed need a replacement switch contact the vendors who advertise on this forum as they may or may not be able to assist you.

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I believe I've seen headlight switches advertised by Roberts. I'm pretty sure they don't have them for all makes and models but they might have yours. Also, when I rebuilt my 49 Plymouth, I was able to disassemble the switches, clean the contacts, and make sure they were working properly. I wound up using all the original dash switches and they all work today. Also, for what it's worth, I stuck with the original 6 volt positive ground and I have no trouble whatsoever. My lights are bright and I never have any trouble starting the engine. I do use the car pretty much every day, which I think makes a difference. 

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Whether or not the new switch is acceptable depends on the current (amp) rating of the switch. If it is rated equal to, or higher than the original, it would be fine. As for 12V versus 6V it is really a matter of personal choice. I rewired my 1941 Dodge a couple of years ago for 6V but I made provisions to go 12V if I decide to. Advantage to 6V is originality but price and availability of parts are benefits of 12V in my opinion. Both work fine.

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First of all; plenty sellers offer 6V stuff, it's just matter of asking around (or google as today..)

Andy Bernbaum who do advertise on this site do have the original correct part. Plenty of seller at eBay offer replacements.

 

However, I'd begin as Don Coatney adviced testing the circuits and making sure where the problem lies.

 

I see that this is also leading to the eternal discussion 6V vs. 12V. 

In my opinion 6V is as good as 12V for these cars.

Most of the problems 6V system gets blamed are actually due to corroded contacts and failed insulation in the old car.

In my case I cannot belive how big difference in 6V cranking new and properly soldered cables made - I actually bought a new 6V battery, but after step one replacing the cables I backed off and left the new battery dry in the self waiting for time that I really will need it.

There are many exiting and useful up-grades you can do for these cars - In my opinion 6-12V conversion is not one of worth-to-do's.

Cheers,

Uncle-Pekka

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it all boils down to what are you comfortable with now and if you intend to stay content with the limited creature comforts/conveniences if you intend to use the car to a greater degree than a weekend short run..if you like it as original the 6 volt is not a question but a very limit to work within...else..upgrade for reason that include options, availability and maintainability 6 or 12 your electrical system should be kept to peak with clean connection, proper size and run lengths of wire and especially clean tight connections..also further investigation into the pro and cons is in order and a full understanding of how things work prior to work to maintain or work to upgrade.. 

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Was your car rewired with properly gauged wire to run 6 v accessories? Remember gwhat Mssr. Ohm said about voltage, resistance and current flow. 14 and 16 gauge wire common to 12 v systems will not carry the amps necessary for 6v loads without causing unwanted resistance.

The other common fault area with the headlamp switch is that, if it is like later models, carries the only fuse in the vehicle. Also check the dimmer switch, contacts can become corroded to the point that they will not pass current. Several cycles of stomping most times will clear them.

Edited by greg g
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Then there are hybrid systems.  I've kept the 6V positive ground system for all the original stuff, starter, lights, radio, etc., and they work fine.

 

For 12V modern stuff, such as cell phones, GPS devices, etc., some people use a separate battery pack, and charge it separately.  Neat and clean, for such small electrical loads.

 

I had bought a 12V pusher fan on the cheap, for parades and other possible overheating conditions.  (And sure enough, I haven't done a parade since.)  To power the fan and the 12V gadgets, I added a second 6V car battery.  From the negative post of the main battery to the positive post of the added battery gives me 12 volts.   I have to recharge the auxiliary battery occasionally.  Maybe it's a clunky and unnecessary solution, but the added complication is something that actually appeals to me.   Now if I can figure out how to add a small alternator for the auxiliary battery...

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you will not get enough added resistance in the length of wire common to the average car to induce any increase in ohm and current draw...given your connections are clean and free of voltage drops...most wire gauge resistance is rated in 1000 feet runs....that is commonly reserved for the component being powered and the source...the wiring and elements of bulbs are such to accomodiate the voltage supply and when mixed is the cuase for resitance change...bulbs are DOT regulated for wattage and the resistance of each per voltage requirement is what regulates current drain. 55watts is 55 watts... The reference to wire size and current load and run be matched and that is differnect for all voltages...there are many quides online for you to read and get up to speed on even if a novice...go to a on line AWG wire chart for these specification...if designing your onw..you will need to know OHMS law to make the correct circuit

Edited by Plymouthy Adams
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A bulb story. This is a bit off topic but yesterday I had to replace a headlight bulb in my daily driver. I bought this vehicle new in 1997. This is the first time I have had to replace any bulb in this vehicle in the past 17 years and around 225,000 miles. I don't recall ever having bulbs in any vehicles that lasted this long. What life span are others getting from automotive bulbs?

 

I bought this new replacement bulb at AutoZone for around 12 bucks and they installed it for free.

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it all boils down to what are you comfortable with now and if you intend to stay content with the limited creature comforts/conveniences if you intend to use the car to a greater degree than a weekend short run...

 

I have to comment on this: I cannot think how 6V system would limit or make it harder to use the car regularly or for longer trips?

It's a good idea keeping a 6V ignition coil with you on long hauls, but hey, it's the same with 12V coil at least here in Europe - Odds are you will not find any coil on today's "service stations" in case you''l blow it on the road.

Other than the ignition parts, does not prevent driving on...

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Pekka...you must not limit yourself to the very box that is the old car with wheels....items such as cruise control, AC stereo, ABS brakes and other modern safety items limited only by your imagination..not every car should be considered by everyone to be at the same standard as when produced..that would be extremely boring...who wants to drive a museum piece...even you with the very parts I have located for your old car proves that stock is not always the way one wants their car...and ignition parts..they are the same as when 6 volts with exception to the condenser   and that value is such that it will not prevent operation..the industry moved to 12 volts but ignition and gauges stayed the same and dropping resistors in the ignition circuit and CVRs in the gauge circuits make it all come together without changing upsetting every production company supporting the industry..

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Most all coils such as the ones used with a standard points ignition are 6 volt coils. Even after the manufactures switched to 12 volts in the mid 50's the coils were still rated at 6 volts. The 12 volts was reduced to something close to 6 volts by using a voltage drop resistor either internal or external to the coil.

 

coil.jpg

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A bulb story. This is a bit off topic but yesterday I had to replace a headlight bulb in my daily driver. I bought this vehicle new in 1997. This is the first time I have had to replace any bulb in this vehicle in the past 17 years and around 225,000 miles. I don't recall ever having bulbs in any vehicles that lasted this long. What life span are others getting from automotive bulbs?

 

I bought this new replacement bulb at AutoZone for around 12 bucks and they installed it for free.

Have had to replace the headlight bulbs on the wife's '09 HHR.  I did not ask if they would, but I do not believe parts stores will replace the HHR bulbs. Last one was noticed before leaving home. I had my wife stop at NAPA on her way to where she was going to snag one in case she was spotted on her way home in the dark hours. It was the low beam that was out, so there was no sneaking home on the low beams. She got stopped, but they let her go when she produced the new bulb with a short explanation. Sometimes they write a "fix it" ticket to show that they have been doing something during their tour of duty. That is a pain as follow up is needed.

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is it just me or is it GM that seems to have a serious problem with bulbs blowing..when I drove to work daily I would see that the majority of new cars with blown bulbs, tail light, registration and yes even head lights were GM cars..what gives..oh I got my theory but it tends to upset GM owners...lol

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I'm amazed at the depth of knowledge among members of this site - and very grateful for it.

In answer to some of the questions - I believe the car was rewired with the correct gauge cables. Having only experienced 12 volt systems in the past,  I've noticed how hefty most of the cabling appears.

The advice to check the amp rating for a replacement switch sounds good. There are 12v switches here in England classed as "heavy duty" so I'll check those out.

One piece of advice to throw into the ring: I read today on a British forum that fitting 12v type battery terminals can cause increased resistance and for example slow down starter motor cranking.  My Plymouth cranks rather slowly so this is another area I will examine.

Thanks again for all the very helpful advice,  fellas  

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Tim, oh Tim...

 

Please read carefully my post before answering...

 

...

I see that this is also leading to the eternal discussion 6V vs. 12V. 

In my opinion 6V is as good as 12V for these cars.

Most of the problems 6V system gets blamed are actually due to corroded contacts and failed insulation in the old car.

In my case I cannot belive how big difference in 6V cranking new and properly soldered cables made - I actually bought a new 6V battery, but after step one replacing the cables I backed off and left the new battery dry in the self waiting for time that I really will need it.

There are many exiting and useful up-grades you can do for these cars - In my opinion 6-12V conversion is not one of worth-to-do's.

Cheers,

Uncle-Pekka

 

Do I say someone should not modify their cars?

 

 

it all boils down to what are you comfortable with now and if you intend to stay content with the limited creature comforts/conveniences if you intend to use the car to a greater degree than a weekend short run..

 

I have to comment on this: I cannot think how 6V system would limit or make it harder to use the car regularly or for longer trips?

It's a good idea keeping a 6V ignition coil with you on long hauls, but hey, it's the same with 12V coil at least here in Europe - Odds are you will not find any coil on today's "service stations" in case you''l blow it on the road.

Other than the ignition parts, does not prevent driving on...

 

I was not commenting against modifications, but merely asked why to convert 6V to 12V. Reliability is not the answer even if I read you previous comment to say so.

 

Pekka...you must not limit yourself to the very box that is the old car with wheels....items such as cruise control, AC stereo, ABS brakes and other modern safety items limited only by your imagination..not every car should be considered by everyone to be at the same standard as when produced..that would be extremely boring...who wants to drive a museum piece..

 

Now you bring up stereo systems, AC, ABS brakes etc.  - OK, I agree you better do 12V system in case you want those nice things to your car.

But hey, let's be honest out there; How many of those who did the 12V conversion ever installed AC or ABS in their 40's cars ? Stereos yes, but anything else?

 

I must be sincere; I do not like "street rods" nor "billet"...

I belive everyone should build his own as per his comforts and dreams, but for me putting modern V6 and mustang sub frame does not make any sense.

Why not buy 2005 mustang if you really prefer drive one rather than these old beasts?

To me the big slow turning but torquey flathead is the soul of these cars.

One who thinks it's only the external appearance is incomprehensible to me.

I know this does not make any sense to most of people, but I find it more fashinating and challenging to do the modifications by using roughly period parts.

One who says modern technology is more reliable does not know anything of these cars.

Properly overhauled and maintained these cars go way beyond you can ever go with a modern computer controlled engine.

What I am after is the FEELING you get blowing down the road powered by half century engines.

I am not limited by period technology - I am being freed and empowered by it!

 

Sorry I was carried away, but it's good to sometimes talk about the ideology behind the hobby. Everyone has his own, this is mine.
 

Edited by Uncle-Pekka
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As advised, check your original switch but if not working they appear on ebay regularly. This is on ebay now. Not mine and I don't know the seller. http://www.ebay.ca/itm/1939-PLYMOUTH-HEADLIGHT-SWITCH-IN-BOX-NOS-MOPAR-853295-/360729787863?pt=Vintage_Car_Truck_Parts_Accessories&hash=item53fd2bbdd7&vxp=mtr

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Uncle-Pekka, on 02 Nov 2014 - 11:50 AM, said:Uncle-Pekka, on 02 Nov 2014 - 11:50 AM, said:Uncle-Pekka, on 02 Nov 2014 - 11:50 AM, said:Uncle-Pekka, on 02 Nov 2014 - 11:50 AM, said:

Tim, oh Tim...

 

Please read carefully my post before answering...

 

 

Do I say someone should not modify their cars?

 

 

I was not commenting against modifications, but merely asked why to convert 6V to 12V. Reliability is not the answer even if I read you previous comment to say so.

 

 

Now you bring up stereo systems, AC, ABS brakes etc.  - OK, I agree you better do 12V system in case you want those nice things to your car.

But hey, let's be honest out there; How many of those who did the 12V conversion ever installed AC or ABS in their 40's cars ? Stereos yes, but anything else?

 

I must be sincere; I do not like "street rods" nor "billet"...

I belive everyone should build his own as per his comforts and dreams, but for me putting modern V6 and mustang sub frame does not make any sense.

Why not buy 2005 mustang if you really prefer drive one rather than these old beasts?

To me the big slow turning but torquey flathead is the soul of these cars.

One who thinks it's only the external appearance is incomprehensible to me.

I know this does not make any sense to most of people, but I find it more fashinating and challenging to do the modifications by using roughly period parts.

One who says modern technology is more reliable does not know anything of these cars.

Properly overhauled and maintained these cars go way beyond you can ever go with a modern computer controlled engine.

What I am after is the FEELING you get blowing down the road powered by half century engines.

I am not limited by period technology - I am being freed and empowered by it!

 

Sorry I was carried away, but it's good to sometimes talk about the ideology behind the hobby. Everyone has his own, this is mine.

 

Pekka...you can upgrade all you want an not be a ROD so to speak...there is a great wide area know as custom or as I would like to call them...personalized...as my car will retain it's form on the exterior to that as stock...and have a few interior changes...how many builders change this stuff and add the accessories...well I cannot account for Finland and other areas of your drivable commute..but here in the US...more than you would ever think do these very upgrades...my 48 Plymouth has all mentioned above...from computer controlled SMPFI right down to the zero emission fuel fill system, body controller, serial buss and air bag plus the ABS brakes....retrofitted Mopar late model AC in all its glory and whatever else you can think of...other than the wheels and possibily the subtle dual exhaust tips you will not notice it much from stock appearances...UNLES you consider the gray tint tempered glass all about except for the DOT approved windshield also gray but laminated by law....but, this feature will prevent most from seeing some of the interior changes..though I have no need for the very fuel filler affixed to the fender..it will remain as a feature..sure no milk in the tit...but is theres it is a period item that does in my opinion define the car and is part of that era..much the same view I have on split windshield, mounted aerials...it is of the era..leave them ....frenching is a cue that has been overdone as much as louvers were just not so long ago......personally I detest things like other brand engines...flat paint jobs, rat rods in any degree of build..any engine overbuilt for the street..brap pipes and chopped tops and slammed suspension and especially tail draggers..but that is just me and I do not own those and if you do that is fine...and if you do not have the time to wrap a wiring harness in the engine compartment..you should not in my book have the time to drive it...come on folks we need to be a bit cleaner is some of the stuff done to these cars..but I rarely will harp on many things..except to poke jabs at GM junk and the three on the tree being totally uncivilized...these are more to get conversation started than anything else..

 

this reply is not an attack on anyone and their build..they are free to do with their car as I am free to do with mine...read these threads...there are daily question of upgrading this or that and how to do and what is your source and especially the electrical as folks DO WANT these very features I speak of..maybe not everyone wants them all but the trend is enough that they do ask..I see a big big following in Europe of the American big car and especially the cult era they mimic that is the US late 50's..tha is fine if that is your build theme...but there are other avenues to explore and while I may not follow them closely..I am not locked out to their existence..

 

As for the 6 verse 12...try to do the very things above and stay 6 volt..that my friend is the driving force behind the very questions and comments that frequent these pages..to think they do not exist is only fooling yourself...that they do not apply to you..yes to that end we can all agree..but do they apply to hobby....INDEED they do..

 

and to the other aspect...modern drivetrains..why not get a new car...why not indeed...there is nothing wrong with liking an older body style and if you give up the other side of the coin like the modern stuff..you only short changing yourself..I love the old cars...but you can keep the boat anchors..again my own opinion..Ihve both and each car will be built on its own merit from stock to extreme modern in an old suit..

Edited by Plymouthy Adams
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My 2.5 cents worth is that when I hot-rodded the Dodge I rewired the car a couple of times till I eventually got it right, however I still kept and run the original 1940 instruments and headlight switch........the amp guage reads amps not volts, the oil and water temp gauges are mechanical with not electricity near them and the fuel guage has a voltage drop or resistor wired into its circuit. The headlight switch works fine with 12 volts going thru it.........as for trying to reuse the original plastic/Bakelite knobs on another switch I'd suggest to be very careful working with that old stuff as it tends to become very brittle, I ended up adapting a metal knob from another switch for my 1940 Dodge headlight switch, it worked fine.......andyd

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I think I'll build mine to run on eight volts, just to start trouble....  :lol:

 

HehHehHeh... I ran my Plymouth as 6 volt for several years, but when it's rebuilt it will be at least 12 volts.

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