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Jump Starting a 6V Car


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I have seen alot of of old car ads on CL and Hemmings that show jumper cables in the trunk. Are they thinking that there is a good chance that another old car may be around to jump them, or is it possible to jump a 6V car with a 12V? I wouldn't think so but just curious. I just assumed that if I my battery went dead, I would have to lug it home and charge it.

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The textbook answer is no, you should never jump start a 6 volt car with a 12 volt battery. You will often find another antique car at the same events that you happen to have your 6 volt car at, so it is likely you will have another 6 volt car available to jump start your car if needed. In the real world, while not a good idea, I have seen 6 volt cars successfully jump started from a 12 volt car. Don't do it, but if you do a quick momentary connection for a quick start with all accessories switched off would be the safest way to do an unsafe act like that.  

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I agree with Matt-

DON'T DO IT !

I have seen a battery explode, potentially hurting folks nearby with Sulfuric Acid.

 

But ... I've had to do it myself a couple of times, and here's what I figured was the safest way to jump-start:

Depending upon if the 6-Volt car was positive or negative, of course,

I connected to "hot"12-Volt battery, or jumper pak's appropriate correcponding Non-Ground cable directly to the starter,

but did not connect the ground - yet.

Then I switched on the ignition, and engaged the starter on the dead/weak car-

after the starter was engaged, and hopefully turning, even if very slowly,

then, and only then, momentarily made ground contact from the "hot" battery or jumper Pak, toa ground area which I could easily reach, and easily disconnect while in the driver's seat  - in fact, just touching ground without actually clamping seems good enough-

that spun the starter like a Merry-Go-Round,

and typically that would start the engine, get you going,

and hopefully a functional generator would continue to recharge a weak battery, 

hopefully get you home, or at least to where you could replace the battery and/or generator.

 

Again - DON'T DO IT IF YOU CAN HELP IT  !!

Edited by Marty Roth
typo, and additional note (see edit history)
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Ran my 6volt Dodge truck for years with a 12 v battery used only for staring and a switch to change the ignition between 6+ 12.  Ran on 6 v generator.  Do not have any lights on while starting.  Charged 12 v battery every so often.  The starter and ignition will take ok if your vehicle starts right up.

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There are 2 ways to do this. First is to disconnect the ground wire at the battery and connect the jumper cables to the cable clamps leaving the ground post alone. This leaves the battery out of the circuit. When the car starts, take the ground cable and stick it back on the battery as you take off the jumper cable. If you are quick the car will not stall.

 

The other way is to have one person turn on the key and work the starter while another connects the battery cable at the same time, leaving it on for only a few seconds till the car starts. Connect the live side, and ground the ground side to the motor not the battery.

 

I have done both ways, they both work and will not damage your battery.

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God protects fools and drunks; I'm a teetotaler which leaves...

 

Done it a couple times, nary a bit of drama. Didn't have the 12v vehicle running. Didn't really give it a second thought at the time; figured since I had the lights & accessories off all was well. Took about 10 seconds both times.

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This was done all the time when six volt cars were common. Make sure everything in the car is turned off. Take the cables off as soon as it starts. Be careful of positive or negative ground. When you were stuck and needed a jump you couldn't be fussy.

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I have done it many times, on a few different 6V cars.  Not ideal, of course, but I haven't had a problem doing so.  Ditto what others have said about all lights off, on and off as quick as possible.  But it raises the question, why hasn't anyone created a 6V jumper?  You'd think there would be a significant market for it in the 6V car world.

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I haven't tried this, but I wonder if you could take one of the 12V jump starters that has a 12V DC outlet, plug in a 12V DC to 120V AC converter, and *then* plug in your 6V charger.   That way you could charge your battery using the 6V charger you have.  Seems a little Rube Goldberg-like, but I'm not sure why it wouldn't work. 

 

I suppose you could also just carry around another 6V Optima battery with jumper cables and use it if you need it!

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If you stand on the driver side of the 12 volt battery car and raise your left foot 8 inches at a 22 degree angle while putting your right thumb into your right eardrum at 9:53 am on Tuesday that is relatively sunny with a ambient temperature between 43 and 59 degrees Fahrenheit combined with a humidity level not in excess of 32 percent ......

 

It Will Be Just 🍑 Good

 

 

Jim

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The problem is not the starter. 12 v will not hurt a 6 v starter. The windings in a 6 v starter are heavier than those in a 12 v. The problem is with the 6 v battery and accessories. You may explode the battery or burn out various accessories but 12 V will never hurt the starter.

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 12V/6v whatever?...

BUT! never connect your truck to a welder!!!

 

 I was out in nowhere land and thought the welder would get me started. I forgot that the voltage of an  open circuit of a welder is way higher than the voltage when welding.

 

 When the high voltage hit the solenoid, it threw in the starter gear so fast that it broke the casting of of the end of the starter!

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The really prepared Craigslisters keep the air cleaner on the seat in case they need a prime. And a few empty cans to turn in for a few cents worth of gasoline.

 

Although it could be a status thing, subliminally telling the buyer they don't need to walk down a row of cars asking "Hey, man, you got a pair of jumper cables?" Don't lowball, I'm not needy.

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First and most obviously, why wouldn't one fix whatever the problem is that will prevent electricals (or anything else, for that matter) in a (hobby) car working properly, instead of ignoring the causes and continue to carry band-aids ? Perhaps a clear sign of someone NOT to be taken seriously as a real (vintage) car enthusiast, just another hack ?* 

 

Secondly, if it's necessary to be driving/operating a vehicle with questionable starting/running abilities due to electrical "problems" requiring jumper cables and not adequate jumper "box" is not available, why not just carry another/extra fully charged battery along also ?

 

Thirdly, if a vehicle listed for sale prominently features jumper cables as potentially necessary accessory, I would use it as sign that the seller is likely tired of and/or unable to fix whatever the problem may be and therefor more susceptible to accept whatever offer I may deem the car in that condition being worth, not what he or she claims/hopes/wants/etc. 

 

As for anyone asking or lusting after 6 Volt jumper "box" and can't find one readily available, I'd suggest looking into production costs of making one or more for such (likely very) limited market and put their money where ...

..., perhaps then an answer to such calls for someone else do it becomes more clear or see my "Second" suggestion.

 

* I admittedly carry jumper cables along with fair amount of service/spare parts and tools for potential problems one can encounter, especially on long distance (i.e. few hundred miles or more) trips, but I also try to keep maintenance and services of everything up to snuff.

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9 hours ago, 1935Packard said:

But it raises the question, why hasn't anyone created a 6V jumper?  You'd think there would be a significant market for it in the 6V car world.

 

If you mean 12 volt vehicle to start a 6 volt vehicle, they do! Well, why else would they make 10 AWG jumper cables?😁

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When my daughter started driving I gave her a '65 Electra to drive. I also bought a jumper box and put it in her trunk. She was warned the the Buick had a very special electric system and could not be used to jump other cars. The couple of times she used it to start a friend's car they thought she was a pretty cool girl to have tools like that.

 

I'm sure the Electra was happier for it.

 

On the jumper cables, it seems like it may have been in a Cheech and Chong movie where I heard one had to be a wealthy man in some neighborhoods to own his own jumper cables. And here's my snob daughter with a jump box and a laborer to keep it charged for her.

 

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9 minutes ago, CarNicopia said:

I carry a second Optima battery.

I do, on more than day-long tours.  My Pierce 8s have two Optimas in parallel, more for additional reserve capacity for night driving than extra-fast starter operation.  More than once, on tour I've removed one of the Optimas and lent it to someone whose generator failed.  On my 4- and 6-cylinder cars (even the 525 cid 1918), I run one Optima but carry a second if the tour is more than one day.

 

All my cars except the Jeepster are positive ground, and that's my greatest worry in getting a jump from a negative ground car, either 12V or 6V.

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TTR. Volvo XC90’s are known to have an electrical problem with the computer that even the factory recall did not fix. I put a jumper box in my daughters car just so it would start and recharge the battery. Two computer changes by the dealer and it still did it. Great car otherwise just didn’t want to start after computer went nuts and drained the battery. Some things can’t be fixed with a repair within a reasonable cost!  
dave s 

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If this was already mentioned and I missed it I'll just repeat - my method. Only works if you have enough 6v power left to run the ignition. Turn on the key to power ignition (be sure you are in neutral) and jump the 12v directly to the starter or if you have a remote starter solenoid to the starter side of that. No risk of battery blowing and 6v starters can take the current. Some engines you may have to get underneath to get to the starter.

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Just push start them.....😄

 

Best safety tip, NEVER put the last connection to a battery terminal! Jump Box, jumper cables, anything that makes a spark.

 

I've seen too many lead acid batteries (and yes, Optimas ARE lead acid too) explode. Sure, I've seen people make sparks at the battery terminals and nothing happened, but once you see what can happen, and have to take people to the emergency room to attend to their eyes........😲

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21 hours ago, SC38DLS said:

TTR. Volvo XC90’s are known to have an electrical problem with the computer that even the factory recall did not fix. I put a jumper box in my daughters car just so it would start and recharge the battery. Two computer changes by the dealer and it still did it. Great car otherwise just didn’t want to start after computer went nuts and drained the battery. Some things can’t be fixed with a repair within a reasonable cost!  
dave s 

Sorry Dave, my commentary was intended for the topic of 6V and "hobby" type vintage vehicles.

I don't "do"* nor care much about modern appliances, but yes, I assume most vehicles, especially modern ones can and do have myriads of electrical problems, regardless of make/model/year.

At this stage in my life, if my (or wife's) daily driver/transportation starts giving me/us grief or offering suggestions of unreliability, it will get replaced, promptly.

 

My accountant's DD, almost a decade old Jeep w/nearly 150K miles and which I've been servicing for her for years, just had couple of problems that I didn't have diagnostic equipment nor interest to deal with, so we sent it to a former dealership mechanic who works out of his house and got it all sorted over the weekend for more than reasonable money.

OTOH, I've been urging her already for a while to consider new or newer vehicle before this becomes that proverbial money-pit.

 

*Heck, I just recently did brakes (pads, rotors and wear sensors) and some scheduled maintenance services on a friends late model Porsche 911, but couldn't check or re-set oil-level readings without taking it to dealership (apparently some modern cars don't even have dipstick's for fluid checks). Fortunately, had an inside guy who helped to get it sorted while I waited.

Edited by TTR (see edit history)
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TTR. Your “hobby car” comment went right over my head. Sorry I missed it. You are right fix the problem on a hobby car instead of bypassing it. There are days when I can’t or won’t is a better word take my 38 out (it is my daily driver) because of something not working correctly. Probably still drivable but why not just fix it.  The other day the rear window would only go halfway down. No big deal but Gracie (one of my two riding buddies) sure would not have been happy. So I fixed it and took her and Sophie (15 year old golden doodle sisters) out for a test ride. Worked great and she enjoyed sticking her head out. 
dave s 

 

ps - my daughter sold the XC90 

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On 2/22/2021 at 6:59 AM, Restorer32 said:

The problem is not the starter. 12 v will not hurt a 6 v starter. The windings in a 6 v starter are heavier than those in a 12 v. The problem is with the 6 v battery and accessories. You may explode the battery or burn out various accessories but 12 V will never hurt the starter.

You have to remember the bendix spring is lighter in the early cars example like model Ts. It is common to break the bendix spring under 12 volt with the starter spinning so much faster with the heavier winding's . So on early cars you have to consider this. 

Edited by Joe in Canada (see edit history)
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Powerglide rear pump will engage at about 15 MPH. I have push started them in my youth, with several kids helping. This also applies to Corvair Powerglides, and you just have to get rolling down a nice hill. Not easy to do in lots of places!😄

 

Turn on key, start pushing in neutral, then drop in Low over 10 MPH or so.

 

Yes, not many of use here on this forum are going to push start an automatic by ourselves! 🤔  Unless parked on a good hill.😉

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17 minutes ago, John348 said:

 

I don't know if I personally could try to push start an automatic, I don't know of anyone who did

  Dual coupling or Controlled Coupling 4 speed Hydramatic also know as= ( Super Hydramatic-Pontiac 1956-1964) (Jetaway-Oldsmobile 1956-1960) ( 315 or P315 Hydramatic- Cadillac 1956-1964) Cannot be pushed started because the pump in the transmission is driven by the engine, there is no pressure to apply the clutches when the engine is not running.

 

  Roto Hydramatic 3 speed four range Hydramatic.   Used by Pontiac 1961-1964, Oldsmobile 1961-1964. Cannot be push started because the pump is driven by the input shaft which is driven or turned by the engine, Therefore with no fluid pressure to operate clutches the transmission will not transmit power and turn the engine.

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bug_62.jpg

Take terminal wires off 50 & 30 of the starter and battery+ post. Take + battery cable and connect to wire that came off #30. Take a 12v battery connect it to 30 and ground take a remote starter switch and connect to 12v battery and sol. terminal. Turn ignition key on, go back to remote switch and press. Don't have a remote starter sw?? use a large flat blade screwdriver to go from the terminal 60 to the solenoid spade and your screw driver becomes the remote switch. The car is still on 6V and just the starter is isolated on 12V.

Like Restorer32 says it won't hurt the starter, in fact when many people convert their VW's or Porsches to 12volts they leave the old 6 volt starter in place.

 

The beauty of having a flat, a completely flat battery in a car that has a  generator  (UNLIKE A ALTERNATOR)  does not need electricity to produce electricity. Sans certain Hydramatic's you can also push start them.

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On 2/22/2021 at 7:47 PM, Jim Bollman said:

If this was already mentioned and I missed it I'll just repeat - my method. Only works if you have enough 6v power left to run the ignition. Turn on the key to power ignition (be sure you are in neutral) and jump the 12v directly to the starter or if you have a remote starter solenoid to the starter side of that. No risk of battery blowing and 6v starters can take the current. Some engines you may have to get underneath to get to the starter.

 

Yes, this is essentially what I described, above

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On 2/22/2021 at 2:49 AM, 1935Packard said:

I haven't tried this, but I wonder if you could take one of the 12V jump starters that has a 12V DC outlet, plug in a 12V DC to 120V AC converter, and *then* plug in your 6V charger.   That way you could charge your battery using the 6V charger you have.  Seems a little Rube Goldberg-like, but I'm not sure why it wouldn't work. 

 

I suppose you could also just carry around another 6V Optima battery with jumper cables and use it if you need it!

 

Typically, there would not be enough amperage with this set-up to jump start,

but given enough time you might be able to use this as a trickle charge

Edited by Marty Roth (see edit history)
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6 hours ago, Marty Roth said:

 

Typically, there would not be enough amperage with this set-up to jump start,

but given enough time you might be able to use this as a trickle charge

 

Yes, that was my thought:  If you have a 10 amp 12V charger, you could charge up the battery for a spell and then probably get a start off of the newly-charged battery.  But just easier to bring another 6V optima and cables!

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On 2/23/2021 at 12:35 AM, Frank DuVal said:

I've seen too many lead acid batteries (and yes, Optimas ARE lead acid too) explode. Sure, I've

I was about 75 ft away, I saw a small submarine propulsion battery explode, lithium ion, that was in a test chamber resembling a walk in cooler, it blew the door off of it, contaminated the factory. It was the largest lion battery made at the time, around 2007.

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    I have been starting 6V cars with 12V for 60 years.  The only explosion I experienced was early one hot, humid 100 degree New Hampshire morning I jumped my 9N Ford tractor with a 12V battery sitting on the ground. I usually take the caps off, but being hot and in a hurry I just hooked it up and hit the starter. There was a spark and an explosion much like the report of a large pistol two feet in front of me. I was sitting there in the seat, stunned looking at the  cap less battery when all of a sudden the caps ( three made together, not singly) came down and landed right back in their holes in the top of the battery. Could that ever happen again?  I put some water in the battery and jumped it and it worked like the explosion never happened. A real waker upper.

    Battery have run down since battery # 1 I am sure. I remember family reunions at a farm in Michigan. The men sitting around in their cars in groups listening to the Indianapolis 500 or Tiger baseball games. Batteries ran down. Before the accessory position in the ignition switch the key had to be on to listen to the radio. Batteries have always run down.

    We also had a Volvo that no one could figure out why it ran down the battery overnight. A 2004. The last Volvo agency mechanic advised me to donate it to charity and let them junk it. I did just that and that problem went away. The very last of decades of Volvos.

 

            Jim43

     

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