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Thread: 6 volt to 12 volt jumper cables?

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    6 volt to 12 volt jumper cables?

    I know you good folks have figured this out already, what are my options? I drive a 6 volt 54 Chev around, what do I do if I ever need a jump start? Are there step down cables available? Can I make some? Is there a safe way to jump from 12 to 6?<P>Help!

  2. #2
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    Re: 6 volt to 12 volt jumper cables?

    Do what most of us do. Jump start with 12 volts. The starter can take it and in fact the faster speed produced will help to start quicker. Turn off all lights and accessories as they can be damaged by the higher voltage.<P>From personal experience: When trying to start a car that is hard to start I frequently use a 12 volt battery or heavy duty charger to get it started. Have never burnt up anything yet.<P>How about Rick or some of you other guys who know much more than I do giving an opinion. ~ hvs

  3. #3
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    Re: 6 volt to 12 volt jumper cables?

    Howard, you did well. However, I usally kick the tire and speak a little Pennsylvania Dutch to it before going to get the cables out. If you have to do this James, make that last cable connection the ground cable on the 12V battery just to be on the safe side and don't leave them connected any longer than you need to.<BR>Rick

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    Re: 6 volt to 12 volt jumper cables?

    Can't begin to count the times I used 12 volts to jump start my Dad's 6 volt Willys Jeepster. Used a heavy duty charger or jumpercables from my Jeep CJ7.<P>Main thing is to make sure everything is turned off first before jumping it.
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    Re: 6 volt to 12 volt jumper cables?

    The joys of a rebuilt engine and a good battery: I have not had to do this since I got the car back together.<P>I have jumped (and probably will again jump) six volt cars from twelve volt sources.<P>However there are some real safety and equipment concerns:<BR><ul><BR><LI>6v lights, radios, etc. can be fried by feeding them 12v. Have all lights and accessories turned off.<BR><LI>There will be a tremendous current draw as your 6v battery tries to bring the 12v battery down to its level. This will:<BR><ul><BR><LI>Heat the jumper cables up real quickly.<BR><LI>Boil electrolyte off the 6v battery causing hydrogen gas to be released. Do not have any sparks near either battery and especially not near the 6v battery. Batteries have been known to explode because of this.<BR>[/LIST]<BR><LI>The coil is not designed for use at 12v and will soon over heat.<BR>[/LIST]<BR>All this points to these precautions:<BR><ul><BR><LI>Make the last connection the ground connection on the 12v system.<BR><LI>Make that last connection to a good ground that is as far away from the 12v battery as you can manage. Remember keep the sparks away from the source of hydrogen gas. This also keeps you away from the ground zero of an acid filled explosion.<BR><LI>Do not leave the cables connected an instant longer than absolutely required.<BR>[/LIST]<BR>Other than that, there is no real problems in jumping 6v from 12v.<P>Tod<P>p.s. Many American 6v cars were positive ground (I don't know about the 1954 Chevrolet). Remember to connect positive to positive and negative to negative. On my Plymouth that means connecting the starter of the old car to the ground of the 12v car. And the ground of the old car to the "hot" post of the 12v battery.<P>------------------<BR><A HREF="http://www.ply33.com" TARGET=_blank>Plymouth: The First Decade</A><p>[This message has been edited by TodFitch (edited 12-21-2000).]

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    Re: 6 volt to 12 volt jumper cables?

    In 1973, I boosted my 6-volt 1952 Chev with Dad's 12-volt something-or-other and the darn 6-volt battery exploded! Dad led me, with my eyes closed, to a nearby bathroom so I could flush my face and eyes of any acid. I was lucky, no harm done other to my clothes.<P>Anyway, I've boosted 6-volt cars many times since, but always disconnected one of the 6-volt connections from the battery first! As long as the generator is functioning, the engine should stay running while you re-attach the 6-volt battery.

  7. #7
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    Re: 6 volt to 12 volt jumper cables?

    Interesting...Glad you are ok. So, if you unhook one of the cables from the bat, tell me where/how you hook up the jumpers?

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    Re: 6 volt to 12 volt jumper cables?

    I think he unhook the ground cable from the bat and hook up the jumper cable to a good ground like the engine block (with no paint, of course)<BR>That means if your car has a negative ground you unhook the negative cable from the bat and hook up the negative jumper cable to ground as I wrote above. The positive batterie cable is then still at the battery and you hook up there the positive jumper cable.<BR>By the way: Do you have often starting problems? There are some batteries with 8 V on the market which give a bit more power. I saw even a battery which give 12 V to start the engine and comes back to 6 V when the engine runs. <P>Tom<p>[This message has been edited by ThomasBorchers (edited 12-23-2000).]
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  9. #9
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    Re: 6 volt to 12 volt jumper cables?

    Those 6V/12V batteries have been around for a long time and work very well. I used them [plural] because I went through several in the 15+ years I used them in a '41 Cadillac.<BR>I finally got around to building an oversize battery box to accomodate a larger, high CCA 6V battery.<P>They were at that time, 1965 to 1980's, made under the name "Orpin." The battery was essentially a 12V battery with a large relay system permanently mounted into the top of the battery. As Thomas says it gave 12V when the starter was engaged and reverted automatically to 6V for running. The installation instructions included 12 possible wiring set ups for various makes of cars. '41 Cad. was #12 and even that required some modification to the starter button wiring.<P>The interesting part was the charging system. It would charge one side of the battery and when you shut off the engine and restarted it would automatically switch to the other side and charge that 1/2. So the full 12V was always charged and you operated on alternate 6V sides while driving.<P>Earlier this year we concocted such a setup for a '13 Cadillac that is a bear to start when it is hot. We used 2 modern 6V gel batteries which fit side by side in the battery box on the running board, and a bunch of relays and switches. However we can only charge one side, so the other battery has to be manually charged every so often. OK on a '13 Cadillac, but you wouldn't want to use that system on a car driven regularly.<P>8V is nice but it is hell on electrical components. You can get 8V bulbs but don't use the radio.<P> hvs<BR>

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    Re: 6 volt to 12 volt jumper cables?

    These 12/6 Volts Batteries are still available here: <A HREF="http://www.antiqueautobattery.com/prod011.htm" TARGET=_blank>http://www.antiqueautobattery.com/prod011.htm</A> <BR>On this site there are some special batteries.<BR>Howard~~My 1912 Cadillac works still with these 4 small mc batteries. They have only 16 to 18 Ah and it is a wonder how this works. The only problem is that when the engine/starter is hot after some miles, the starter will not engage and turn the engine. Normally when I push the small button between the front seats, something turns in the starter and when I push the cluth the starter engage and turn the engine but if it is hot there is nothing which turns in the starter...<BR>When the starter cooled down, it works again. I can't find the problem.<P>Tom
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    Re: 6 volt to 12 volt jumper cables?

    Any lead acid battery when its being charged gives off hydrogen gas. This will explode if subject to any kind of spark. The last connection on and first off should be to a ground away from the battery. Additionally the caps on the dead battery should be removed and the holes covered with a rag so that pressure doesn't build up in the battery.

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    Re: 6 volt to 12 volt jumper cables?

    I own a 53' Ford that is a 6-volt. I would not advise jumping your car off with 12-volt jumper cables. When I did the generator blew out. But, If you have to then there are two ways.<BR> 1) Only let the cables stay on our car for the least amount of time.<P> 2) Place the negative cable to the metal of your car then place the positive on the positive post of your battery. This will lower the amount of voltage that goes to your battery. <P>

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    Re: 6 volt to 12 volt jumper cables?

    Thomas, I have a suggestion about your hard-starting-when-hot-Cadillac...<P>I had the same problem with my '52 Chevy (see post above ? I learned a lot with that car), which I believe was caused by a slightly bent starter motor armature. Since the shaft was not quite straight, cleanace to the fields was very tight on one side of the armature - when the engine, and thus the starter, were hot, expansion caused the armature to lock up or at least drag.<P>For several months prior to replacement, I parked on an incline if I expected to only be stopped a short while, or otherwise enlisted the help of passengers/passersby to give me a shove.

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    Re: 6 volt to 12 volt jumper cables?

    Chris~~<BR>My thoughts go in the same direction with the problem.<BR>I have no idea how the starter/generator works inside in all details. At the moment I don't want to disassamble it. In the main things I know it of course but for example I don't know what is turning in the starter when I push the button. If this thing is not turning the starter will not engage and turn the engine when I push the cluth.<BR>By the way: I don't like it also to hook up a 12 V to a 6 Volt system for start...It is always a risk.<P>Tom
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  15. #15
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    Re: 6 volt to 12 volt jumper cables?

    Thomas ~ What is happening inside your starter when you push the button is that current is fed to the starter motor to start it spinning, but NOT to engage the flywheel to turn the engine over. The purpose of this pre-spin is to allow the starter gear to slip into the teeth on the flywheel. When this gear does not turn the teeth of the two gears butt together and won't engage.<P>I believe all motor generators work in much the same manner. My '13 Cadillac has the button on top of the light switch panel on the right kick panel. My '14 and '24 Buicks both begin to spin when the switch is turned on, eliminating one operation, pushing the button.<P>If your starter will not pre-spin when hot, you may very well have an internal binding problem in the starter. In my case, the starter will pre-spin when hot, but just turns the engine over so slowly that it won't catch. Hence 12V start cured my problem. ~ Howard

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    Re: 6 volt to 12 volt jumper cables?

    I checked out the 6/12 and 8 volt bats, seems like an excellent source for restoration parts. I am thinking about going to 8 volts. QUESTION: How will it keep charged with a 6-volt generator? The caption under the photo of the 8 volt unit says generator output must be increased, how do I do that? I have an adjustable regulator; I thought that changed the amps, not volts?

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    Re: 6 volt to 12 volt jumper cables?

    We have some cars with a third brush were I can adjust the charging. For example: At our 1918 Hudson Super 6 the generator had an output around 8 volts. This is too much for a six 6 Volt battery. So I adjusted the 3rd brush that the generator has an output with 7.20 volts.<BR>The 2nd thing is that in the shop manuals for Model As stands that you can adjust the ampere output with this 3rd brush. I think this means that volt and amperes increase both.<BR>I think you should try it what will happen if you adjust your regulator. Check it out with an voltmeter at the battery terminals.<P>Thomas
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    Re: 6 volt to 12 volt jumper cables?

    Third brush generators are basically constant current devices. If there is no other regulation of voltage (i.e. external regulator) then you can just put in an 8v battery. If you have external regulation (most American cars after the mid-1930s), then you would have to adjust the regulator.<P>In any case, I think an 8v battery is a bad idea. Your lights will burn out quickly and your coil will be cooking itself and also die young. The only reaons for an 8v battery is because your engine and/or electrical sytem are defective. Fix the defects and the need for 8v goes away.<P>Just my not so humble opinion. <P>------------------<BR><A HREF="http://www.ply33.com" TARGET=_blank>Plymouth: The First Decade</A>

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    Re: 6 volt to 12 volt jumper cables?

    I must say that I agree with Tod.<BR>Remember: All cars with 6 volts system worked fine as they were new. Why should we put now these modern 8 V or 6/12V batts in it? We should find the problems why a car starts hard with the 6 volt batt, so that we can use the original design batts.<P>Thomas
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    Re: 6 volt to 12 volt jumper cables?

    I do very much agree that the 6 volt system worked well when the car was built. I believe my engine is tired and needs a rebuild, it cranks fine but takes a while to catch. This wears the bat down too fast. I would like to preserve the stock system, but it will be a few years untill I have the funds to rebuild. Why else might it take a long time to start? Fuel is present in a clear filter by the carb.

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    Re: 6 volt to 12 volt jumper cables?

    Lots of good ideas on jumping a 6 volt car. One I didn't see but is a variation of the disconnecting a cable tip. I have jumped 6 volt batteries directly but have always been afraid that one would blow up on me sometime. Finally dawned on me a few years ago, hook up the ground side then jump directly to the starter or starter side of the solenoid, the 6 volt battery is out of the circuit as far as the 12 volt battery and nothing to connect and reconnect. Just put the car in neutral or park, turn on the ignition and start the engine from under the hood. You are only connected long enough to start and no overloads on any of the cars system (except the starter). <P>Been jumping my 8N Ford and Crosleys like this for a while now, with no problems.<P>Jim...
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    Re: 6 volt to 12 volt jumper cables?

    James~~<BR>Do you have these start problems after the car stood still for a week or more, or do you have also after 1 day since the last tour? <BR>There are several possibilities why a car starts hard.<P>Tom
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    Re: 6 volt to 12 volt jumper cables?

    It is hard starting after even one day sitting. While warm from driving the same day, it starts right up. After sitting a week or so its starting fluid or forget it.<P>I have new points, plugs, rotor, condenser, cap, wires, coil, battery, cleaned out the carb, new oil, filter, timing seems right (never did put a light n it) I have not checked the compression, it smokes a little on acceleration. Any advice would sure be appreciated.<BR>James

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    Re: 6 volt to 12 volt jumper cables?

    Hmmm, this is not an easy one... You changed all important parts. <BR>I have only some few ideas, now. There is one cable from the coil to the distributor. This one gives current through the contacts to the coil to produce the spark. Have you checked this small cable and the terminals? The terminal must be very clean otherwise the current is too low. <BR>If you talk about the ignition timing. If the ignition is too much retarded the engine will start hard, also.<BR>Yes, and then you should make an compression test.<P>Tom
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    Re: 6 volt to 12 volt jumper cables?

    James, have you checked whether there is fuel in the float bowl after the car sits overnight? Some carbs are prone to siphoning the fuel through the idle circuit as the engine cools down. This would account for starting when the engine is still hot but not starting after it sits for some time. Some carbs have an air bleed in the idle circuit to prevent this. This is a very tiny hole that if plugged cancause this.

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