The Ford Barn

Ramblin Reck · 12-24-2021, 04:22 PM

Have not had to do this yet but I am sure some of you have. I would "assume," which is always dangerous, but Negative to Negative and Positive to Positive and in any given sequence to connect cables?

Mart · 12-24-2021, 04:41 PM

Yes, of course.
Just make sure the bumpers aren't touching. (Old car steel bumpers that is.)

V8COOPMAN · 12-24-2021, 05:46 PM

Quote:

Originally Posted by Mart

Yes, of course.
Just make sure the bumpers aren't touching. (Old car steel bumpers that is.)

Mart .....Can you explain WHY? Play a game with me below.

Suppose your pick-up was still 6v POS GROUND. You go out to start the truck one dark morning and the battery will barely turn the engine over. You know that if you could just get the engine to turn over fast enough, it will start. So, you back your T-bird out of the garage and line it up behind your truck, with bumpers TOUCHING. I will jump into the truck and help you accomplish the 'PUSH'. I will turn the ignition switch to "ON" in the truck. I will also push-in on the clutch, and put the truck transmission in 2nd gear. As I wave out the window for you to begin PUSHING the truck with your "beloved" T-bird, I turn-on the truck's light switch, as it is still dark outside. You begin pushing the truck. The truck battery is still strong enough to light my headlights somewhat. (REMEMBER, our bumpers are still in contact. The T-bird is 12v, NEG GROUND, & the truck is 6v POS GROUND. Both vehicles are sharing a GROUND through the bumper contact....AND IT CAUSES NO PROBLEMS!) As you build up a little speed with the T-bird, I ease out on the clutch, and the truck engine comes to life just like we knew it would. And even though both vehicles were sharing UN-LIKE grounds through the bumper contact, no sparks flew, the lights worked properly in both vehicles, and nothing was damaged.

So if you will, please explain this bunk about not letting bumpers touch on vehicles with UN-LIKE grounding types. I'd like to know why that seems to be important.

Years ago, I drew-up this comparison of how a 6v POS GND circuit and a 12v NEG GND circuit can safely SHARE a COMMON Ground, BELOW. Do you see ANY problems with this circuitry? DD

RalphG · 12-24-2021, 10:17 PM

I've started my six volt 52 Merc several times with a 12 volt boost but I by-pass the six volt battery. Just have the ignition on, touch one of the booster cables from the 12 volt to the starter side of the solenoid and the starter kicks in cranking real fast. Worked for me.

bbrocksr · 12-24-2021, 10:35 PM

Don't let the bumpers touch when you are jumping, Doesn't matter when you are pushing to start. If you let the bumpers touch when jumping it's the same as using 3 cables , your bumpers become the third cable hooking the two unlike grounds together causing big sparks. Not bunk.
Bill

tubman · 12-25-2021, 12:10 AM

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This is 2021. High quality jumper boxes are available at a reasonable price (if it's important to you). The last thing I would consider my car to be is a support vehicle for someone who can't afford a decent battery.

GB SISSON · 12-25-2021, 10:06 PM

For years in the 90s I daily drove a stock 38 tonner. As I got more into the hit n miss engines and other heavy stuff I bought a tandem axle trailer with electric brakes. The tonner still had cable brakes and they were quite effective, and 6v positive system. To operate the trailer brakes I mounted a 12 group 24 on the tongue set up negative ground and wired that way into the controller in the cab. Worked fine... Never used the cable brakes when towing. Years later I had this thought... Was that not a dead short somewhere? Mixing of 6 and twelve volts. Just seemed wrong. But never any problems... Dumb luck?

bbrocksr · 12-26-2021, 12:35 AM

Are you still into Hit& Miss engines? I've got a few.
Bill

41ford1 · 12-26-2021, 09:51 AM

Quote:

Originally Posted by V8COOPMAN

Mart .....Can you explain WHY? Play a game with me below.

Suppose your pick-up was still 6v POS GROUND. You go out to start the truck one dark morning and the battery will barely turn the engine over. You know that if you could just get the engine to turn over fast enough, it will start. So, you back your T-bird out of the garage and line it up behind your truck, with bumpers TOUCHING. I will jump into the truck and help you accomplish the 'PUSH'. I will turn the ignition switch to "ON" in the truck. I will also push-in on the clutch, and put the truck transmission in 2nd gear. As I wave out the window for you to begin PUSHING the truck with your "beloved" T-bird, I turn-on the truck's light switch, as it is still dark outside. You begin pushing the truck. The truck battery is still strong enough to light my headlights somewhat. (REMEMBER, our bumpers are still in contact. The T-bird is 12v, NEG GROUND, & the truck is 6v POS GROUND. Both vehicles are sharing a GROUND through the bumper contact....AND IT CAUSES NO PROBLEMS!) As you build up a little speed with the T-bird, I ease out on the clutch, and the truck engine comes to life just like we knew it would. And even though both vehicles were sharing UN-LIKE grounds through the bumper contact, no sparks flew, the lights worked properly in both vehicles, and nothing was damaged.

So if you will, please explain this bunk about not letting bumpers touch on vehicles with UN-LIKE grounding types. I'd like to know why that seems to be important.

Years ago, I drew-up this comparison of how a 6v POS GND circuit and a 12v NEG GND circuit can safely SHARE a COMMON Ground, BELOW. Do you see ANY problems with this circuitry? DD

No problem for a push start. You will have a short circuit when you try to connect the positive posts. Many sparks and possibly a battery explosion.

paul2748 · 12-26-2021, 08:00 PM

To jump start a 12V positive ground from a 12 V negative ground, you should disconnect the cables on the 12V negative ground source. Just like jumping from a free standing battery

bbrocksr · 12-26-2021, 08:18 PM

Or don't let the bumpers touch.
Bill

RalphM · 12-26-2021, 11:04 PM

back in the 70’s, I would have to jump my 6v 55 Ford. I never owned a set of cables(some people who helped me did). But many a time I WOULD put the bumpers together and use a piece of scrap steel to jumper between batteries.
worked every time! With a few sparks of course!
Since most cars were 12 V then, you didn’t want them touching very long anyway.

12-24-2021, 04:22 PM	#1
Ramblin Reck Senior Member Join Date: Jul 2021 Location: Savannah, Georgia Posts: 245	Jump starting a 12V Positive Ground Have not had to do this yet but I am sure some of you have. I would "assume," which is always dangerous, but Negative to Negative and Positive to Positive and in any given sequence to connect cables? __________________ "Engineers like to solve problems. If there are no problems handily available, they will create their own problems!" ROGER, WILCO, OUT!

12-24-2021, 04:41 PM	#2
Mart Senior Member Join Date: May 2010 Location: Solihull, England. Posts: 8,744	Re: Jump starting a 12V Positive Ground Yes, of course. Just make sure the bumpers aren't touching. (Old car steel bumpers that is.)

12-24-2021, 10:17 PM	#4
RalphG Senior Member Join Date: Sep 2014 Location: Sask. Canada Posts: 2,424	Re: Jump starting a 12V Positive Ground I've started my six volt 52 Merc several times with a 12 volt boost but I by-pass the six volt battery. Just have the ignition on, touch one of the booster cables from the 12 volt to the starter side of the solenoid and the starter kicks in cranking real fast. Worked for me. __________________ https://www.youtube.com/user/roosty6/videos

12-24-2021, 10:35 PM	#5
bbrocksr Senior Member Join Date: May 2010 Location: Yakima Washington Posts: 913	Re: Jump starting a 12V Positive Ground Don't let the bumpers touch when you are jumping, Doesn't matter when you are pushing to start. If you let the bumpers touch when jumping it's the same as using 3 cables , your bumpers become the third cable hooking the two unlike grounds together causing big sparks. Not bunk. Bill

12-25-2021, 12:10 AM	#6
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,303	Re: Jump starting a 12V Positive Ground Sponsored Links (Register now to hide all advertisements) This is 2021. High quality jumper boxes are available at a reasonable price (if it's important to you). The last thing I would consider my car to be is a support vehicle for someone who can't afford a decent battery.

12-25-2021, 10:06 PM	#7
GB SISSON Senior Member Join Date: Jan 2014 Location: Orcas Island Washington Posts: 4,914	Re: Jump starting a 12V Positive Ground For years in the 90s I daily drove a stock 38 tonner. As I got more into the hit n miss engines and other heavy stuff I bought a tandem axle trailer with electric brakes. The tonner still had cable brakes and they were quite effective, and 6v positive system. To operate the trailer brakes I mounted a 12 group 24 on the tongue set up negative ground and wired that way into the controller in the cab. Worked fine... Never used the cable brakes when towing. Years later I had this thought... Was that not a dead short somewhere? Mixing of 6 and twelve volts. Just seemed wrong. But never any problems... Dumb luck? __________________ Owner/Operator of 'Jailbar Ranch' on the side of Mt. Pickett. Current stable consists of 1946 1/2 ton pickup turned woodie wagon with FH V8, 1947 Tonner Pickup (red) mostly stock with exception of a cummins 6at turbo diesel, 1946 Tonner Pickup (green) with 226 cu in 6 cyl flathead, 1979 Toyota landcruiser wagon, completely encased in 1947 Ford Jailbar sheet metal. Ok, cornbinder rear fenders..... 'Rusty ol' floorboards, hot on their feet' (Alan Jackson)

12-26-2021, 12:35 AM	#8
bbrocksr Senior Member Join Date: May 2010 Location: Yakima Washington Posts: 913	Re: Jump starting a 12V Positive Ground Are you still into Hit& Miss engines? I've got a few. Bill

12-26-2021, 08:00 PM	#10
paul2748 Senior Member Join Date: May 2010 Location: Midland Park, NJ Posts: 3,979	Re: Jump starting a 12V Positive Ground To jump start a 12V positive ground from a 12 V negative ground, you should disconnect the cables on the 12V negative ground source. Just like jumping from a free standing battery __________________ 48 Ford Conv 56 Tbird 54 Ford Victoria

12-26-2021, 08:18 PM	#11
bbrocksr Senior Member Join Date: May 2010 Location: Yakima Washington Posts: 913	Re: Jump starting a 12V Positive Ground Or don't let the bumpers touch. Bill

12-26-2021, 11:04 PM	#12
RalphM Senior Member Join Date: Nov 2015 Location: North Pole, Alaska Posts: 2,651	Re: Jump starting a 12V Positive Ground back in the 70’s, I would have to jump my 6v 55 Ford. I never owned a set of cables(some people who helped me did). But many a time I WOULD put the bumpers together and use a piece of scrap steel to jumper between batteries. worked every time! With a few sparks of course! Since most cars were 12 V then, you didn’t want them touching very long anyway.