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Old 10-30-2011, 11:10 AM   #1
TinCup
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Default 6 Volts versus 12

Many of the local club members have converted from 6-12volts in their cars. While I run a 6 volt alternator everything else is pretty much as Henry designed it. Yes I run additional connections for cell phones and gps but they all run on 5 volt USB connections and that is no problem. Just reversed the wiring on the female connections and the adapters work just fine.

Other than brighter headlights and a faster spinning starter what is the real advantage here?
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Old 10-30-2011, 11:29 AM   #2
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Default Re: 6 Volts versus 12

Easier to find batteries and to jump start.
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Old 10-30-2011, 11:38 AM   #3
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Default Re: 6 Volts versus 12

Other things being equal, the headlights will not be brighter. Equivalent headlight bulbs produce the same candlepower or lumens. 6 volt bulbs pull twice the current at half the voltage to do the same work as equal-rated 12 volt bulbs.

I converted my car to 12v many years ago, when it was "the thing" to do. If I were putting it together now, I wouldn't convert as there are solutions for all the extra things I have such as, like you, phone and gps.

Seems like most people convert to cure symptoms caused by poor grounds. It's easier to fix the grounds than to convert.

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Old 10-30-2011, 11:58 AM   #4
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Default Re: 6 Volts versus 12

As Joe says, the basic advantage is, for any given load, you have 1/2 the amps going through the wires and switches at 12 volts compared to the current flow at 6 volts. Flowing 1/2 the current through a switch or starter motor generates 1/4 the heat. That switch will last longer. That starter motor will not get so hot so fast.

12 volts is also less sensitive to slightly poor grounds or imperfect wire connections. You might lose 1 of your 12 volts with a bad connection, but the light or horn, or whatever it is, will still work.

On a 6 volt system, that same bad connection will lose 2 volts (due to double the current) and only leave you with 4 volts to light the light (it will be dim) or blow the horn (it will sound weak). So, as Joe said, you need to be more diligent with all of your grounds and connections with 6 volts to keep them clean and tight. It can be done. Cars ran on 6 volts for decades.

Personally, I would opt to push start an A with a dead or weak battery instead of jumping it. There is usually enough juice to get a spark (if the starter is not cranking, pulling the battery volts down really low). Getting to the battery on the A to jump it is a pain (under the floor mat or carpet) and jumping to the battery cable under the hood at the starter switch is too easy to accidentally touch a ground and start arcing.
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Old 10-30-2011, 03:30 PM   #5
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Default Re: 6 Volts versus 12

Changing over to 12 volts is pretty simple. install a 12 volt battery in place of the six volt battery, replace the coil with a 3.0 ohm coil or add a ballast resister to the six volt coil, replace the bulbs and its done. If the horn is original it will need a voltage reducer or it may lose its smoke. If you want negative ground, reverse the battery cables, the wires behind the ammeter and the wires on the coil. If you are running the original generator it will take a couple of seconds to repolarize or you could install a higher output alternator if you plan on running accessories or the brighter quartz halogen bulbs. I like the positive ground 12 volt conversion that I use on my roadster with no added electrical accessories except for a right tail lamp.
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Old 10-30-2011, 04:06 PM   #6
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Default Re: 6 Volts versus 12

I am converting to 12v next week.

To get the current tail lights to act as turn signals (in addition to what they do now) should I purchase the "Ugly Bulbs" from Snyder's? They are halogen and I really want bright stop lights to keep the crazies off my rear...

In defense of those that believe 6v is a better option, the following is a list of "things I will buy" to complete my conversion:

12v alternator - $125
12v battery - $90
Battery disconnect switch - $24
Extra cable for disconnect switch - $8
Modern starter bendix - $25
Modern ignition switch w/accessory position - $12
0-30 Amp ammeter - $9
Horn voltage reducer - $17
Electric wiper voltage reducer - still haven't found one
Turn signal kit - $53
Conversion kit to make Cowl lights turn signals - $36
Amber lens for Cowl lights - $12
Turn signal beeper - $6
Halogen headlights conversion kit - $97
Tail light halogen signal bulbs, aka Ugly Bulbs - $25

In addition, since I will have the 12v system completed I am adding:
Water temp gauge w/illumination - $63
Temperature probe pipe for water temp gauge - $17
Oil pressure gauge w/illumination - $57
Chrome dual gauge holder - $74
FSI Zipper distributor w/flame thrower coil and stainless intermediate shaft - too much $$ to admit

So, yes, you could stay with the standard 6v system and things would work just fine...so why do we do all these things??? Crazy I guess. Guilty as charged...
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Old 10-30-2011, 04:35 PM   #7
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Default Re: 6 Volts versus 12

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Originally Posted by buyitsmart View Post
...so why do we do all these things??? Crazy I guess. Guilty as charged...
me too!

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Old 10-30-2011, 06:03 PM   #8
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Default Re: 6 Volts versus 12

Wow! Tell the guys at FS that the Sooner Club recommended them and see if that doesn't get you a little price break.
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Old 10-30-2011, 06:29 PM   #9
Jim/TX/GA
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Default Re: 6 Volts versus 12

Quote:
Originally Posted by buyitsmart View Post
I am converting to 12v next week.

To get the current tail lights to act as turn signals (in addition to what they do now) should I purchase the "Ugly Bulbs" from Snyder's? They are halogen and I really want bright stop lights to keep the crazies off my rear...

In defense of those that believe 6v is a better option, the following is a list of "things I will buy" to complete my conversion:

12v alternator - $125
12v battery - $90
Battery disconnect switch - $24
Extra cable for disconnect switch - $8
Modern starter bendix - $25
Modern ignition switch w/accessory position - $12
0-30 Amp ammeter - $9
Horn voltage reducer - $17
Electric wiper voltage reducer - still haven't found one
Turn signal kit - $53
Conversion kit to make Cowl lights turn signals - $36
Amber lens for Cowl lights - $12
Turn signal beeper - $6
Halogen headlights conversion kit - $97
Tail light halogen signal bulbs, aka Ugly Bulbs - $25

In addition, since I will have the 12v system completed I am adding:
Water temp gauge w/illumination - $63
Temperature probe pipe for water temp gauge - $17
Oil pressure gauge w/illumination - $57
Chrome dual gauge holder - $74
FSI Zipper distributor w/flame thrower coil and stainless intermediate shaft - too much $$ to admit

So, yes, you could stay with the standard 6v system and things would work just fine...so why do we do all these things??? Crazy I guess. Guilty as charged...
You do not need to do nearly all of that to convert to 12 volts. It might be a convenient time to do it, but it's required.

For example, you can install turn signals in 6 volts...
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Get personalized service. Deal directly with the guy who will drive the truck moving your stuff.
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Old 10-30-2011, 09:21 PM   #10
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Default Re: 6 Volts versus 12

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Originally Posted by TinCup View Post
Many of the local club members have converted from 6-12volts in their cars. While I run a 6 volt alternator everything else is pretty much as Henry designed it. Yes I run additional connections for cell phones and gps but they all run on 5 volt USB connections and that is no problem. Just reversed the wiring on the female connections and the adapters work just fine.

Other than brighter headlights and a faster spinning starter what is the real advantage here?
I'd stay with six volts. All you need is a $60 regulator to replace the cut out and you can crank your generator up to enough amperage to keep your battery charged and run an extra tailight and sealed beam headlights. Alternators stress the waterpump bearings and look silly on an older car. 12 volts are very hard on the fly wheel ring gear and starter drive. My GPS runs fine on 6 volts. But do what you want, it's your car.
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Old 10-30-2011, 09:28 PM   #11
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Smile Re: 6 Volts versus 12

Have a list of bulbs both 6V and 12V for all Model A applications, plus candlepower of both so can choose brighter bulbs. Another list has all electrical parts and part numbers plus parts to convert a GM altenator to single wire at a much lower cost than is being asked by vendors. If anyone intrested send me an email at jrelliott42@gmail.com
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Old 10-30-2011, 09:30 PM   #12
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Default Re: 6 Volts versus 12

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Originally Posted by Paul from Maine View Post
I'd stay with six volts. All you need is a $60 regulator to replace the cut out and you can crank your generator up to enough amperage to keep your battery charged and run an extra tailight and sealed beam headlights. Alternators stress the waterpump bearings and look silly on an older car. 12 volts are very hard on the fly wheel ring gear and starter drive. My GPS runs fine on 6 volts. But do what you want, it's your car.
I started this conversation because I was trying to get a consensus of reasons beyond the ones I stated of why you would want to make the conversion.
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Old 10-30-2011, 09:49 PM   #13
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Default Re: 6 Volts versus 12

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Other than brighter headlights and a faster spinning starter what is the real advantage here?
The capability of instant repair. Every parts house in the country has an AC Delco alternator for about $50 bucks. I have had such an experience. However, I also believe in "if it ain't broke, don't fix it!" Another point, that fast spinning starter will eventually smoke itself. Another personal experience.
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Old 10-30-2011, 10:04 PM   #14
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Default Re: 6 Volts versus 12

I've been driving six-volt iron since getting my license over 25 years ago.

I have never felt compelled to change to 12-volts; the six-volt stuff has always worked.

My 87,000-mile '28 Special Coupe came with a six-volt positive-ground alternator already in it; it works, so I'm not planning to change it. Have toured nearly 7,000 miles with it in just under two years, no dead batteries, fried alternators, cooked starters or any other ugly stuff. It starts and runs, winter and summer.


If the rig you have is working fine and suits your needs, why change it ?
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Old 10-30-2011, 10:28 PM   #15
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Default Re: 6 Volts versus 12

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Originally Posted by Milton View Post
The capability of instant repair. Every parts house in the country has an AC Delco alternator for about $50 bucks. I have had such an experience. However, I also believe in "if it ain't broke, don't fix it!" Another point, that fast spinning starter will eventually smoke itself. Another personal experience.
That's an interesting thought. However a good Model A generator will outlast us all so I for one don't need a "quick fix" on the road. Now it's true that some folks over the years have fried a generator (and drained the battery) from a stuck (junk) cutout because they don't notice the ammeter pegging. I saw that when I was a kid but I just whacked the cutout to pop it loose. An easy solution is to use a voltage regulator. I actually got one from Tom Wesenberg 6-7 years ago that replaces the third brush but never got around to installing it. I restored original cutouts and they are pretty much bullet proof but there are other benefits to his regulator so I WILL use it when I get to it.

BTW, do you have any idea how many DAYTIME running hours you can get on a Model A without a generator? When I was a kid I probably did a good six hours on the road.
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Old 11-01-2011, 10:11 AM   #16
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Default Re: 6 Volts versus 12

How many NIGHTIME hours can you get without a generator charging using 50cp headlights and 2 10cp tail lights?
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Old 11-01-2011, 10:21 AM   #17
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Default Re: 6 Volts versus 12

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How many NIGHTIME hours can you get without a generator charging using 50cp headlights and 2 10cp tail lights?
If you have a 6 volt system, these bulbs would probably be drawing 10 to 12 amps, so you'll have to divide that into the number of amp-hours on your battery label.

Remember, the deeper you draw down a battery, the harder it is on the battery and shortens it's life.
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Old 11-01-2011, 11:56 AM   #18
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Default Re: 6 Volts versus 12

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As Joe says, the basic advantage is, for any given load, you have 1/2 the amps going through the wires and switches at 12 volts compared to the current flow at 6 volts. Flowing 1/2 the current through a switch or starter motor generates 1/4 the heat. That switch will last longer. That starter motor will not get so hot so fast.
Heat is a function of watts not voltage. When you halve the current but double the voltage the watts or heat stays the same. You can reduce the wire size but then you increase the resistance cancelling the gain. The savings in a 12 volt car is in the reduced cost of the wire.
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Old 11-01-2011, 12:23 PM   #19
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Default Re: 6 Volts versus 12

I agree with You, I have not been compelled to switch to 12 volts either. 6volts is "original" at times it has it's faults, but That is what the car was back then. Enjoy the originality, My car does just fine with 6 volt system as original.
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Old 11-01-2011, 10:00 PM   #20
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Default Re: 6 Volts versus 12

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Heat is a function of watts not voltage. When you halve the current but double the voltage the watts or heat stays the same. You can reduce the wire size but then you increase the resistance cancelling the gain. The savings in a 12 volt car is in the reduced cost of the wire.
You are correct, when looking at the load (bulb being lit, horn being blown, etc.).

The heat that I refer to is generated by the resistance found inside the switch contacts or the slightly corroded connector. The power (heat) generated there is I-squared times R. Half the current (at 12 volts) generates 1/4th the heat -- in the switch or connection.

See http://www.electronics-tutorials.com...resistance.htm

I agree with you that you can use a smaller diameter wire, too, if you want to.
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