1949 12 volt conversion?

[Thomas Bredahl]

For a couple of reasons, I am thinking about converting my '49 to 12 volt.
What are the up's and down's and what are the potential problems?

I would appreciate advice from succesfull "converters"

Thanks

Thomas

[kkarrer]

Thomas,
      I converted my 50 Coupe to 12 volt (and later sold it to a guy in Holland who is still very happy with it).  Call or e-mail me and I'll walk you through what you need to do the job.  In my opinion it's very worthwhile.  I've just converted my 41 Coupe which is just a bit harder.  It gives you many advantages, BUT there are guys here on the CLC site who will argue against it for some sound reasons.  Here are some of the advantages:
1.) If you need to jump start your car or someone elses, you can.
2.) You can use some modern conveniences (cell chargers, computers, radios, Garmins, battery chargers, etc.)
3.) You can use your original wiring harness or replace it with a new 6v harness and still go with 12v, so the authentic look is still there and the wire is heavier.
4.) You can use a Newport two speed electric wiper motor in place of that vac unit and never have to sweat whether or not you vac. unit will work and pass inspection. (You replace the knob that Newport has on their unit with your old knob...same location and it looks stock. No, I don't work for Newport.  I just recommend stuff that has worked for me.
5.) You'll have the option of adding modern a.c.
6.) It's been my experience that you increase the marketability of your car when you convert to 12v and if done right, it's really not detectable when the car is shown.
7.) You can buy a 12v battery anywhere.  I use Omni types for more power, reliability, and no acid spills.
I see it as a "best of both worlds" solution.

YES, 6v will work very well if you have proper grounds, etc.,  ( I can hear some of the guys growling as they read this...sounding like a poorly grounded 6v starter.), but it doesn't give you some of the advantages of a 12 system.  You have a relatively modern car with a great engine and other design features. 12v just makes sense to me. Cadillac went to 12v in 1953.  There were good reasons for that.  Stick with your 6v harness if it's in good shape.  If not I can recommend at least 3 good sources for a new 6v harness that looks original.  In the long run, I think you'll be happy that you converted to 12v.
Ken Karrer 1941 6227D coupe
kkarrer@austin.rr.com
512-626-7268

[Thomas Bredahl]

Thanks for your reply Ken!
I will send you an email.

Just to clarify, I have driven the car five seasons without much trouble, other than the dreaded bad ground cable thus draining the battery over time, so I have been ok with the 6 volt system as such.
But I am getting ready to do a complete chassis overhaul, to prepare the car for my next 30 years  of ownership and would really like to have a trailer hitch for my caravan. That, here in Denmark, is only possible if I go to 12 volt.
I just want to get the most use out of my great fastback as possible, since it will easily carry us all on vacations etc.

[Caddy Wizard]

I converted a 49 to 12v and it was wonderful.  I kept another 49 6v and it was wonderful --  no electrical or starting issues whatsoever.  I have a 50 that is still 6v and it is wonderful -- no electrical or starting issues whatsoever.  I can provide as much information as you might want to convert the 49 to 12v.  The big question is why are you motivated to do it?  If it is to improve reliability, don't do it.  We can walk you through the steps to make your 6v negative ground car work as well as any 12v car, with instant starting, good lights, etc.  Most modern small electronics (GPS, Ipods, etc) use a car charger that actually only needs 5v and the charger clips the 12v down to 5v.  So a 6v cigarette lighter port works great to power a GPS or Ipod or phone charger.  On my 6v 1950, I had the radio worked on and while they kept it 6v, they added a port that allows me to plug in an Ipod to play music files or play FM radio.  Cost me $120 and keeps the original working radio intact, but allows me to play FM or my own playlists on a 62-year-old 6v tube radio.  Fantastic!


But if you want air conditioning (the reason I converted one 49 to 12v), there is no practical way to add AC and keep the car totally 6v.  You COULD keep most of the car 6v and add a second battery and alternator for 12v just for the AC (and maybe a modern stereo).  But that is sort of busy under the hood.  No, if you want AC, I would convert the car to 12v.  But you had better inspect the cloth-covered wiring first to make sure you are comfortable with the additional power that might go coursing through the old wires.  Replacing a wiring harness on a 49 is an expensive proposition.


Either way, it is your car and you should do what feels right for you.  There is no single right solution.


Call me to discuss if you want.


Art Gardner
404 375 3750

[pauldridge]

Here are a few notes I made when converting my 40 Sixty Special to 12V Negative Ground.  There are plenty of generic checklists of common items to follow on the internet.

I've also included my modified wiring diagram, showing the changes I made to add a modern fuse block, with relays to reduce current load on the ignition switch.  I believe these systems are relatively unchanged throughout the '40's.

[pauldridge]

No, if you want AC, I would convert the car to 12v.  But you had better inspect the cloth-covered wiring first to make sure you are comfortable with the additional power that might go coursing through the old wires.  Replacing a wiring harness on a 49 is an expensive proposition.

Art Gardner
404 375 3750

Art,

That is all good advice, and I concur with most.  I too have vehicles converted to 12V specifically in order to have A/C here in sweltering Texas, and other 6V vehicles for driving in Fall through Spring.  However, I do disagree with your warning about the existing wiring not being up to carrying the "additional power".  In fact, 12 volt systems require less amperage, and thus smaller gauge wires for all applications.  That was the main reason they went to 12 Volt (and now 24 volts on some higher end vehicles), to reduce the size and weight of the wiring.

The existing harness will be more than adequate to power any EXISTING components with 12 volts.  Of course, if you are going to be adding high-power-consumption accessories such as A/C or electric fans, you'll of necessity be using new, appropriate-sized wiring for those.  Just make sure those new accessories get their power source right from the alternator/battery (through appropriate breakers/fuses of course) and not through the 70 year-old ignition switch. 

On my cars, I commonly run a 50-75 Amp relay to provide power to a modern fuse buss.. the ignition switch then only provides the minimal power needed to trigger the relay, which is designed to handle any current loads you can throw at it.  such a relay can be had for around $10.. Cheap insurance to save those contacts in the aging ignition switch!

I'm happy to provide wiring diagram for this simple setup on request.

[Caddy Wizard]

Paul,


Maybe I didn't spell it out as fully as you have, but I agree with you.  The original wiring is fine for 12v bulbs and whatnot.  As long as you use the original wiring harness for only as much loading as it was originally intended for, it will be fine (again, assuming it is in good shape).  Where you can get into real trouble is overloading the original harness with greater current loads (like adding AC).  I too kept the lights and original stuff on the original (but new) wiring harness and added a second harness for the air conditioner and modern stuff.

[Thomas Bredahl]

Thank you guys, for a lot of good insight and info on the matter.

I still have one source to go to regarding the trailer hitch issue (rules of the danish inspection system), but that will settle if I am going the 6 or 12 volt route.
Again, the only reason I would want to go 12 volt is to make the car able to, legally, tow our caravan thus making it more useable to us as a family car.
I have had so many great miles in that fastback and just want to get the most of her.

I just got a fine email from Ken (thanks a lot Ken) with conversion details and should anymore info be needed, I will get back to you all.

Thomas

[Philippe M. Ruel]

the only reason I would want to go 12 volt is to make the car able to, legally, tow our caravan thus making it more useable to us as a family car.

Can't you feed the trailer harness in 12 V through 6-Volt relays inside the trunk ?
I intend to feed headlights and taillights on my '52 through relays, still in 6V, because of (1) headlight power and current needed (2) taillights / rear turn lights dimming (and therefore hardly visible in daylight) by voltage drop through the too-long original wiring.

[bcroe]

One of the advantages of 12V (there are many) is you may now use any size
alternator you chose, to match up your loads.  The alternator puts out more
current on demand, both at idle and cruising.  And the the alternator is a
simpler, lower maintenance system generating no radio interference.  I
dumped my last generator, because I was fed up with the brushes going
out every 40,000 miles (annually for me).  Bruce Roe