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My 6 volt car doesn't start with 6V but starts with 12 volt


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So I bought my first classic. 1954 Chrysler Windsor Deluxe. Price was too good and hence I inherited a minor lemon. Enough story.

 

Drove the car home and later in the evening pumped gas and on the way back home, car died at a stop light. Opened the hood and found a 12 volt battery. Jumped the battery from a 12V jeep. Started and ran for a minute and died. So though ok alternator, sorry generator not working and it's not because I measured the meter across it and its not generating any volts while running. Read the name plate to research online and i realized that generator is a 6V generator, then I looked at the starter, it's a 6V starter. Looked at voltage regulator, It's a 6V regulator. Looked at starter relay, it's a 6V too... all original.

 

Then I thought, why did the seller put in a 12v battery and i don't see no conversion kit what so ever.... So went to autozone and bought a 6V battery and installed it. Tried to start and all i hear is the click from relay. Starter isn't even trying to start. Then I put the  fully charged 12 volt battery that came with the car back in and tried starting now starter is trying to crank. So i hooked up my 12V booster/jumper and car started fine.

 

So as of now, I am starting the car with a 12 volt battery w/ a negative ground installation, generator not charging (located a re-builder) and a potential positive ground car. I am seeking help with the following items:

  1. Why my 6V starter isn't cranking with my new 6volt battery but starts with a 12 volt battery/booster?
  2. Is my car positive ground, how to determine it without relying on the battery setup? Because if the last owner just threw in a 12v battery to start and sell it, then i don't know what else he did with the battery setup. What i can tell you is, the ground cable which bolted to the engine only fits on the battery's negative terminal (for both 12v and 6v batteries). So is it a negative ground car?

Some data for question number 2: Lights are working fine even with 12 volt battery. They are bright! and I ran on the original 12 volt battery with lights on for like a hour. 

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Edited by Arun Nella
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Did you ask the previous owner what the deal is with the 12 volt battery? You may get your answer there. Follow the battery cables to see which one is the ground (I believe it should be positive if my memory doesn't deceive me). The cable with the larger hole for the battery post is positive.

Edited by keiser31 (see edit history)
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Something is wrong and by far the easiest and cheapest route is to keep it 6v and fix what is wrong. First thing to check is the battery cables. They should be quite thick, twice as thick as 12v cables, as thick as your thumb. If someone put on cheap parts store cables they won't do.

 

Next is to check that all connections are clean and tight. 6v systems are picky that way. If you have a good 6v battery, good cables, good connections, and it still won't start it is time to have the starter rebuilt. Look in the yellow pages for a local auto electric shop or rebuilder, they will be able to rebuild it for you.

 

You are lucky it ran on 12v and didn't burn anything out. If you do run it on 12v make sure lights, radio etc are turned off and don't run it for more than 15 minutes or the coil is apt to overheat.

Edited by Rusty_OToole (see edit history)
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29 minutes ago, keiser31 said:

Did you ask the previous owner what the deal is with the 12 volt battery? You may get your answer there. Follow the battery cables to see which one is the ground (I believe it should be positive if my memory doesn't deceive me). The cable with the larger hole for the battery post is positive.

I did and "I didn't change anything in the car since I owned it." As far as tracing the battery cables, the ground cable will only fit on the negative terminal of the battery. So is it a negative ground car? But then why does the starter say 6 volt positive shift on its name plate. #Confused.

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30 minutes ago, Rusty_OToole said:

Something is wrong and by far the easiest and cheapest route is to keep it 6v and fix what is wrong. First thing to check is the battery cables. They should be quite thick, twice as thick as 12v cables, as thick as your thumb. If someone put on cheap parts store cables they won't do.

 

Next is to check that all connections are clean and tight. 6v systems are picky that way. If you have a good 6v battery, good cables, good connections, and it still won't start it is time to have the starter rebuilt. Look in the yellow pages for a local auto electric shop or rebuilder, they will be able to rebuild it for you.

 

You are lucky it ran on 12v and didn't burn anything out. If you do run it on 12v make sure lights, radio etc are turned off and don't run it for more than 15 minutes or the coil is apt to overheat.

I wanna keep the car 6V at any cost. So try to get it started with 6 volt. Battery cables are pretty thick and almost double the size of my 12 V daily driver. I have to check the connections for corrosion. What kinda voltage should I expect at the starter terminal when I attempt to start?

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Arun, Don't get too hung up on that battery cable only fitting on the negative side. Odds are very good that it's been replaced over years of service. Get a shop manual or Motors or Chilton manual for your car, and keep it handy. You need to be able to look up specs like this at your finger tips...even during a power outage, or whatever. 

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Like I said, get some shop manuals for this car. You'll save yourself a lot of headaches. 

 

Attached are specs I scanned from a 1954 MOTORS manual. In the TUNE-UP SPECS chart, you'll note that it lists all Chrysler cars as POSITIVE GROUND, right up through 1954. Under the Generator specs, you'll also notice that Chrysler used BOTH 6 volt and 12 volt systems in 1954. 

Chrysler tune up specs.jpg

Chrysler Generator specs.jpg

Chrysler starter motor specs.jpg

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Good luck sorting out this project. You might actually enjoy "solving the puzzle," if you force yourself to adopt an attitude that it is a challenge which you are undertaking, to see if you can solve the puzzle. You'll just have to make sure you really did finally get it right, before you head out on a long trip in your new friendly automobile...especially if you plan to take family or friends along with you for the ride! 

 

Cheers! 

 

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Not yet mentioned is the size of the battery.  (Cold Cranking Amps)

Not all 6 volt batteries are equal. A 6 volt Volkswagen battery wont work. A 6 volt lawn tractor battery wont work. . . . 

It takes a big heavy (truck size?) battery to create enough AMPERES to spin over that beast. 

Unlikely that Autozone or any 'popular' parts house is going the have the correct battery. 

 

BTW - Welcome to the collector car hobby. One of the things car collectors ENJOY is FIXING and REPAIRING their cars. :)

 

Serious car people do not expect their new purchases to be perfect the first time (FYI- a lemon is just a car that needs further diagnosis) and they expect to have to LEARN about their car. (as you seem to want to do)

Repairing helps you to 'become one with your car'.  ;)  Stick with it, enjoy the car ON IT"S TERMS and you can have a lot if fun. 

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A good indicator (and a starting point) of what the previous owner/s may have done is to check the head light globes. Are they 12v or 6v?

The globes wont care if its -ve or +ve ground.

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You guys are amazing.

My 6V battery can put out 710A. So my is infact positive ground 6 volt (learnt from manual). So I am gonna first of all wire battery with positive ground and try to start the car. I have the generator disconnected since I have to get it rebuilt anyways.

 

However, I am wondering how everything worked with 12V negative ground setup!, the starter relay, starter motor etc.!!!

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Short answer: some/many of those things mentioned do not care whether the ground is positive or negative. . . Many other things however DO care very much. ;)

 

12 volt vs 6 volt - 12 volt is an increased 'pressure' in your system. 6 volt things spin faster, burn brighter and get hotter when given a 12 volt diet. Likely why the seller might have made the switch. :wacko:

 

However, putting 12 volts to a 6 volt system is like whipping an old tired horse. It might force something to work for a short term, but it is going to kill things in the long term.  :(  It is a good choice on your part to sort out your issues by retaining the 6 volt parameters. 

 

Perhaps you can post a picture of your battery and your cables?  There are things that experienced eyes can see that you cant, yet. 

Edited by m-mman (see edit history)
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15 hours ago, lump said:

Like I said, get some shop manuals for this car. You'll save yourself a lot of headaches. 

 

Attached are specs I scanned from a 1954 MOTORS manual. In the TUNE-UP SPECS chart, you'll note that it lists all Chrysler cars as POSITIVE GROUND, right up through 1954. Under the Generator specs, you'll also notice that Chrysler used BOTH 6 volt and 12 volt systems in 1954. 

Chrysler tune up specs.jpg

Chrysler Generator specs.jpg

Chrysler starter motor specs.jpg

 

Thank you @lump for taking the effort. I found myself a shop manual and yes you are correct. Its a positive ground 6V car. I am now trying to remove the generator. Removed two bolts (one from the adjustment linkage and other from the engine body). This car has power steering so the pump is connected at the back end of the generator. Any tips on how to detach the generator from power steeling pump without draining the fluid?

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Arun, 

Sorry, I've never dealt with that on a Chrysler product before. But I'm sure there are lots of guys here who can provide expert advice.

 

You might also try posting just that specific question on the Chrysler Products forum, further down the AACA Forums page. Mopar guys are sure to hang out there. Good luck! 

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I had to get my generator rebuilt on a 56 Imperial with the PS on the back.

The pump simply unbolted from the generator, I think it was just a tang that had to be lined up right to put it back together.

Even though they had gone to 12 volt neg. ground by then I  would bet the pump would be very similar.

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Starter and generator typically needed rebuilt every 30,000 miles in those days. But the rebuild was simple, new bearings brushes and turn the armature, clean and test parts, done. The plain bearings need to be oiled when you do an oil change, just one or 2 drops. I would use synthetic oil for long life. Do not tighten the belt too tight, unlike alternators which have roller bearings it is not necessary and the bearings won't stand it. You should be able to deflect the belt 3/4" by pressing with your thumb before it is completely tight.

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6 volt systems require GOOD connections everywhere, especially the ground.

My guess is the starter is dragging down the voltage to the coil so you're getting lousy spark.

Clean up all the connections and see what happens.

The starter may need some work too.

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This question came to my mind today while preparing to switch my car back to Positive ground from the current negative ground setup. Since my car starts fine with negative ground setup at battery, wouldn't switching polarity at battery connection force the starter to run in the opposite direction? Isn't that a risky move?

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3 hours ago, Arun Nella said:

This question came to my mind today while preparing to switch my car back to Positive ground from the current negative ground setup. Since my car starts fine with negative ground setup at battery, wouldn't switching polarity at battery connection force the starter to run in the opposite direction? Isn't that a risky move?

In a word, no. Switch the battery to positive ground. Check your connections and make sure your battery is fully charged. Be sure you have good spark and enough fuel.  A 6 volt system will turn over slower than a 12 but as was said you need to have the correct 6 volt cables. Smaller cables will overheat and not conduct the current required.  Try posting here for more help if these suggestions don't solve the problems. .http://p15-d24.com/page/index.html  Specifically for early Mopars from about 1940 to 1959.

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I switched the polarity at the battery. Cleaned connectors at battery, positive going to engine, negative going to starter relay. Only click no crank. Put a 12V booster and starts cranks but no start. I didn't switch the polarity back to see if the car still starts.

 

I have ordered a wrench set from amazon which I am waiting on. I am tired of working with ratchets and adjustable. :)

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Have you checked to see what voltage the light bulbs are?  Pull a bulb out and check the numbers on it and report that information back here. 

Is it possible that someone converted the starter and generator to 12 volts and left the original tags on them?

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If your wires are in good shape/size and a new battery with clean connections thought then I'd be looking into the Soleniod.  Time to pull the starter and get both of them rebuilt.  Preventative maintenance at the least.   Also make sure you sending a good 6 volts to the solenoid when the key switch is in the crank possition.  A bad ignition switch  might only be sending 4 volts.  

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  • 1 month later...

6 volts system was always a source of electrical problem. With the advance of modern technology  life has become a little more tolerable. To start with, the cables must be 2 zero or heavier  in size. CLEEN GROUND and tight connections. I have seen cable connections ,the quick fix type, peel off the insulation, push in and tighten the 2 screws. (it is a source of problem) Terminals MUST be soldered properly. Heavy ground strap from the engine block to the frame must be clean and tight. ALL 6 VOLTS CABLES ARE HEVIER THAN in 12 VOLTS SYSTEMS. Heavy duty batteries are usually 9 or 11 plates. Both batteries, whether sealed or with caps are good. I would use one with the caps so I will be able to top off with water when necessary, if using a generator.( I will discuss the reason later)

 

Since you have a mix of 6 and 12 volts, boy, you are in big trouble. THEY DO NOT MIX. You may change the complete system one way or the other. NO MIX. The starter may already be damaged and also the generator. Get the generator rebuilt with the regulator as a unit or replace with a 6 volt alternator .The starter and solenoid is also suspect. Most likely the system is positive ground. If the bulbs are 12 volts, by using a 6 volt battery they will glow dim. By using a 12 volt battery to light up a 6 volt bulb it will light up very brightly

To know if your charging system is working ,start the vehicle and run for a few minutes and bring down to idle speed, turn on the lights and heater motor. If the engine RRM drops, the system is working fine , if not check for head lights or other grounds  or malfunctioning components. I recommend changing the ignition coil . The low tension wires should be 24 gauge or heavier. You may also have ignition (burnt out coil) or  problem in the distributor. THAT 12 VOLT BATTERY MAY HAVE WIPED OUT OR SERIOUSLY DAMAGED  ALL ELECTRICALS.

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To put this in perspective when everything is right the engine will turn over slowly but start easily. A well tuned engine will start in one or 2 seconds just like a modern car at least once it is warmed up. It may take a little work to get everything right but then it should stay right for years. You may just be dealing with 60 years of 'deferred maintenance'.

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2 hours ago, trini said:

By using a 12 volt battery to light up a 6 volt bulb it will light up very brightly

 And for a very short time! :D

 

2 hours ago, trini said:

The low tension wires should be 24 gauge or heavier.

 Typo? How about 14 awg or better?  I use 16 or 17 awg (found some extremely flexible 17 awg test lead wire) for the points wire on 12 volt systems, 6 volt systems should be heavier, therefore  I though you meant 14 awg.

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I love to read to read your comments. It is a pleasure. What a great gang.

"typo"  it should be 14 AWG. My observation is 16 AWG is used mostly in 12 volts system. I am subject to correction. In my 2017 Colorado the wires are so thin I cannot even see them. Dodge Brothers used 12 volts system around 1917 or thereby with the original wire being 14 AWG. Yes RustyOtool. you are right if everything is correct there should no problem. 

Because of low voltage and high current , if everything is right, 3 grunts and the engine comes alive. What I emphasize is GROUND, clean connections. I may be accused of rambling .But I will tell you from experience to prove a point. A Ford tractor, I think was  L 9 came in the garage, driver complaining of low battery . The electrician replaced the alternator. Problem persist. I was given the job finally. With the engine running at idle I hooked up a voltmeter between the output terminal and chassis frame. Next  I Used a 14 gauge  wire jumper from alternator frame to  chassis. The voltage went up from about near 13 volts to 14 plus volts. The problem was chassis ground to engine. This is a common problem  overlooked.

Cheers mates. Have a nice day. By the way I have a DB 12 volt distributor I think a 1917,  to give away for the cost of shipping. Interested ? phone me at 905 889 0621 or hsahu8034@gmail.com

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If you grind and grind long enough you can overheat a 6V starter enough to melt the solder on 12v.

 

When they went to 12v they also went to a finer tooth ring gear and starter gear. They did not do this for fun. The faster spinning starter will chew up the gears a lot faster than on 6v.

 

What usually happens is someone gets a 6v car, it won't start, because it has bad cables or a worn starter. So they spend $500 converting everything to 12v. Then the starter burns out so they put on a new starter and cables which is all it needed in the first place. Except now they are out an extra $500 and we keep getting plaintive questions about why their 6v system doesn't work on 12v. Eventually they dump the car because it is a lemon. And it is, now that they are done messing with it.

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  • 2 years later...

Just want to add..........I have a 1953 Chrysler new yorker w/ 331 V8. 6 Volt POS ground. It had a hard time turning over, so I put 3/00 battery cables on and I swear it turns over now like a 12 volt and always starts within a few seconds. Very happy with the new cables

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  • 2 weeks later...

Per my memory & fallible mind:  Way back then they used generators, but not alternators.  So you could run your car without a battery if you started it by rolling it down a hill.  You could make starting easier when the existing battery would not crank the car, by hooking a 2nd 6 volt battery in series with the existing 6V (weak) battery, thus going up to 12 V (less internal resistance) briefly.  So you could start the car with the 2 batteries in series, then hook back up just one 6 volt battery to drive away with.  Even an automatic transmission car in those days could be started by rolling it down a hill or pushing it (they had real bumpers then) to 50 mph.  With manual transmission, a much slower push should work.  Thus the use of 12 V could be only for a few seconds, which didn't seem to hurt anything (but don't have the radio on).   I had a friend whose standard procedure in jumping cars was to hook a 2nd battery in series just long enough to start the car. 

(Different topic: Now don't rebuild your engine in your driveway (like my friend did), then try to start it by pushing it, if that car is automatic transmission or say goodbye to your transmission, since the newly rebuild engine has too much friction & the transmission can't handle it in a push-start situation.)

Edited by Gumboocho
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I sure enjoy reading the comments here. I’ve had my share of trials with 6V systems. I own a 1953 Chrysler, all stock 6V. It works great! 
 

I also own a 1938 Plymouth. 6V too. Never underestimate what a previous owner may have done. People with little understanding do weird things, unaware of the consequences. 
 

My ‘38 starter was a mess. Wouldn’t turn over worth a darn. 12V would turn it lickety-split. The seller proved it to me when I was looking at the car to buy it.  Later I pulled the starter. The armature was a mess. Partially melted I suppose from all the 12V it had seen. I cobbled spare pieces together and built a new starter. Works great now on 6V. 
 

I started a You Tube channel to share all my vintage mopar experiences with new, up and comers to the hobby.  Many topics have been covered. Starters. Generator output testing. 6V electrical systems. Carbs and lots more. There are videos that may help you in your 54 Chrysler journey. 
 

My advice is pull the starter and generator. Get them both checked and serviced as necessary. Get the engine spinning over. Then a compression test to learn where you may have to go next. 
 

Here’s a link to my You Tube channel if interested. 
 

https://m.youtube.com/channel/UCVoBq2i7wl4w0W4JB6cAMjg

 

 

 

 

 


 

 

Edited by keithb7 (see edit history)
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The rebuilt 346 V8 on my Cadillac Speedster refuses to spin unless I switch over to the 12 volt system.  These engines are notorious for exhibiting this problem, and often will not respond to heavier ground wiring , rebuilt starters, etc.  Works well for me , as I can switch electrical input with a flick of a switch.

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@autoluke said (I can't make the quote feature work this morning): "The rebuilt 346 V8 on my Cadillac Speedster refuses to spin unless I switch over to the 12 volt system.  These engines are notorious for exhibiting this problem, and often will not respond to heavier ground wiring , rebuilt starters, etc.  Works well for me , as I can switch electrical input with a flick of a switch."

 

In my experience of 42 years with a Cad 346, there are the following inherent problem areas: 

* cables should be at least 00,

* starter solenoid's contact disc, attached with a horseshoe clip, should be filed or machined to remove corrosion

* distributor often fails to retard when engine is shut down due to flat spots on the three ball bearings running in the track--replace bearings and track OR use a Dyna-Flite aftermarket full ball bearing plate

* replace starter fields with high-torque units

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Years ago worked in a garage where a mechanic went nuts trying to fix a 1955 Dodge Red Ram hemi hard start problem. In the end he sent the starter to a local auto electric shop to be rebuilt and they found someone had installed 12V field coils in a 6V starter! With the correct starter it started fine.

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On 4/28/2021 at 6:59 PM, Rusty_OToole said:

Years ago worked in a garage where a mechanic went nuts trying to fix a 1955 Dodge Red Ram hemi hard start problem. In the end he sent the starter to a local auto electric shop to be rebuilt and they found someone had installed 12V field coils in a 6V starter! With the correct starter it started fine.

We had the identical problem recently.

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Posted (edited)

How about doing some diagnosis.  Follow this list and you should be able to fix your car.

 

1. Install the 6 volt battery with the ground positive as you indicate that it should be.

 

2. Check the battery voltage at the battery with the ignition off. On a fully charged battery, it should be about 6.3 volts.

 

3. Keep the leads of the volt meter on the battery terminals and try to start the car.  Does the battery voltage stay the same or does it go down? Does the starter turn over?

     A. If the battery voltage stays the same and the starter does not turn over, the battery is probably good, but a guarantee.

     B. If the battery voltage goes down more than one volt while the car starter is engaged, the battery is either not charged or bad.

 

4. Keep the positive lead of the volt meter on the battery and put the negative volt meter lead on the starter terminal where the cable comes from the battery.  Try to start the car.  Does the battery voltage stay the same as when the negative lead of the volt meter was at the battery terminal?  If it does, then the battery cable under load is good.  If it is less at the starter than at the battery, the cable has high resistance and needs to be cleaned or replaced.  When starting a car, the voltage at both ends of the battery cable should be the same. If not, bad cable.

 

5. Repeat step 4 for the other cable except keep the do it for the positive cable that is going to the car frame.  

 

If these checks show no voltage drop on the cables with the starter turning over then the cables are good, then you probably have a starter that needs to be rebuilt.

 

Any questions, let me know.

 

Also a quick check on the starter would be to use a jumper cable directly from the battery to the cable terminal on the starter if there is room to do it.

Edited by Larry Schramm (see edit history)
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