Electrical: 6v to 12v Inverter

[markindy]

When I told a friend that I had a 6v, positive ground car, he gave an inverter that he never used when he had British cars. He suggested it may work on the cigarette lighter as a way to charge a phone. Looking at the limited instructions, it is bolted onto the dash as a common ground, and then produces a positive 12v output. This thing scares me, as it pushes the limits of my high-school electronics class education. How can a 12v positive output still use a positively grounded chassis?
I've gone back several years in the forum pages, and found a few posts from RadioRoy...but I'm still scratching my head on how this can work.

[Big Dan]

When I told a friend that I had a 6v, positive ground car, he gave an inverter that he never used when he had British cars. He suggested it may work on the cigarette lighter as a way to charge a phone. Looking at the limited instructions, it is bolted onto the dash as a common ground, and then produces a positive 12v output. This thing scares me, as it pushes the limits of my high-school electronics class education. How can a 12v positive output still use a positively grounded chassis?
I've gone back several years in the forum pages, and found a few posts from RadioRoy...but I'm still scratching my head on how this can work.

Weird Electrical Jerry Rigs 101!

On the boat I'm restoring - the one with the '51 Champion [soon to be] in it, my dad originally installed a 49 Champion. For some reason as 6-volt components wore out, he replaced them with 12 volt and eventually used a 12-volt battery to power the boat. But for the remaining 6-volt components he simply drilled a hole in the top of the battery in the center and inserted a stud to pull 6 volts out of it. Don't ask me how that worked either. But he was an Electrical Engineer working on Aircraft in the late 1940s to mid 1980s at CONVAIR!

I have a pretty solid grasp of electricity, but still think it's strictly VOODOO! I'm really anxious to hear the inputs on this one!

[E. Davis]

Back in 1955/56 when cars started coming out with 12 volt systems as standard our police two way radios were old 6 volt Motorola's and small departments like ours couldn't afford to buy new 12 volt models so the radio tech's installed a third connection on the 12 volt battery to isolate 6 volts for them and they worked fine until funds came in to buy new ones. Where there is a will and a money shortage there is a way.

[Big Dan]

Back in 1955/56 they were still testing nuclear explosions above ground upwind from population centers!

[larkregal62]

Don't think it will work, doesn't the phone charger need a NEGATIVE ground???

[Big Dan]

YES, and both the charger and the phone are critically sensitive to polarity!

[Jeffry Cassel]

Don't think it is possible. (When you say Convair I think B-36 which doesn't have much in common with a Champion!) (Did you know that that 10 engine bomber was so complex that it took 12 hours to preflight it!)

[Big Dan]

Yes, but in the Air Force they have special ground crews that preflight their planes. In the Navy we on the flight crews did our own pre-flights and even the P-3C took 4 hours to pre-flight. It was modeled after the Lockheed "Electra" btw and just about everything on it was electrically driven - even the propeller RPM governors.

[RadioRoy]

How about a picture or a brand name and model number, or all three?

[yeroldad]

Roy, Be nice to have your contact info. Tried to send you a PM but SDC didn't let me. Scott, AKA "Yer Ol Dad. I'm wondering what inverter you recommend.

[RadioRoy]

My email address is in my profile.

[StudeRich]

Are you SURE that Inverter doesn't actually put out 12 Volts Negative from 6 Volts Positive ?

I understand that those do exist, and it would work if you Isolate the Unit: Gauges, Radio, Stereo, Tape Player, Amplifier, Lighter whatever you plan to Power up.

[Big Dan]

Are you SURE that Inverter doesn't actually put out 12 Volts Negative from 6 Volts Positive ?

I understand that those do exist, and it would work if you Isolate the Unit: Gauges, Radio, Stereo, Tape Player, Amplifier, Lighter whatever you plan to Power up.

My impression was that an "inverter" converts DC power to AC.

[Buzzard]

Big Dan,
Correct as my "off grid" house inverts DC power(supplied from solar, wind and generators) from our battery bank (24 V) into regular house power. Anyone coming into our house would never know we are NOT connected to the grid. Everything works as would be expected. There just aren't any wires above ground.
As for the OP's request, I would make a Fiberglas Hawk dash a must until everything can be sorted and verified.
Luck,
Bill

[jcharlestc]

When I told a friend that I had a 6v, positive ground car, he gave an inverter that he never used when he had British cars. He suggested it may work on the cigarette lighter as a way to charge a phone. Looking at the limited instructions, it is bolted onto the dash as a common ground, and then produces a positive 12v output. This thing scares me, as it pushes the limits of my high-school electronics class education. How can a 12v positive output still use a positively grounded chassis?
I've gone back several years in the forum pages, and found a few posts from RadioRoy...but I'm still scratching my head on how this can work.

"...but I'm still scratching my head on how this can work."

Unless the unit was made for a 6-V, POSITIVE GROUND car originally, it WON'T work; simple as that. The fact that it is meant to bolted to the dash, and that is supposed to provide "the ground", ensures that it won't work...and could start a fire, if you're not diligent.

There ought to be a law against using and calling anything metal on a car, "GROUND".

[52 Ragtop]

There IS something out there! I had the radio in my 52 Commander converted to AM/FM. Also had them add in "something" (NO clue how they did it) anyway, I also have a 6 CD changer mounted under the seat. I'm still running a 6V positive ground. I called the shop, he told me, "to hard to explain, but it will work" and it has for the last 22 years!

I'm NOT an electrical wizard!

Jim

[Big Dan]

Ok, I've seen that as well, but the question I have for you is: is your 12V/Neg ground stereo actually grounded to the chassis of your car or is it isolated with the "converter" providing the proper 12V neg ground? You see that and also this discussion are not about "does the box work," we know it does. What's important is the correct way to integrate it into the existing SYSTEM. so it does what it's supposed to do without causing problems anywhere else. When a shop installer tells you that something is too difficult to explain it simply means he doesn't know how it works either (or he thinks you're a moron). And, frankly, he doesn't need to know how it works either - only that it does. What he DOES need to know is the correct way to wire it in and make an effective part of the existing electrical SYSTEM, so it works and does so safely. Same thing in this discussion.

[Big Dan]

Ok so let's talk about all the weird inventions that were made during the 1950s that were to be used to turn your basic functional car into a luxury hotel. "Remarkable gadgets ruled!

An inverter of this type really has NO practical use in supporting the original electrical equipment of your vehicle as manufactured. They were used to allow people to hang all sorts of FODDER in their cars - AC fans, hair dryers, coolers, refrigerators and all kind of other junk powered by 120V ac power intended for use in your house.

Honestly you don't need this contraption. If you want to charge your cell phone in your Studebaker, buy a solar panel and bolt it to the trunk lid! No that's technology! LOL!

[Lark Hunter]

The device you're referencing is called a "DC to DC Converter", and they are available in flavors that step 6 volts to 12 volts and switch polarity from positive to negative ground. I'ma guess that the provisions to mount it to the dash are electrically isolated... or at least the output side needs to be isolated from your main electrical system. So, you have two wires in and two wires out, or is it one wire in and two wires out?

I've seen some cheap Chinese converters online that are branded as "6-to12v inverter" or "6-to12v dc converter"; both are exactly the same, and priced the same. An inverter changes DC to AC.

[Lark Hunter]

Weird Electrical Jerry Rigs 101!

On the boat I'm restoring - the one with the '51 Champion [soon to be] in it, my dad originally installed a 49 Champion. For some reason as 6-volt components wore out, he replaced them with 12 volt and eventually used a 12-volt battery to power the boat. But for the remaining 6-volt components he simply drilled a hole in the top of the battery in the center and inserted a stud to pull 6 volts out of it. Don't ask me how that worked either. But he was an Electrical Engineer working on Aircraft in the late 1940s to mid 1980s at CONVAIR!

I have a pretty solid grasp of electricity, but still think it's strictly VOODOO! I'm really anxious to hear the inputs on this one!

That's a cheap n' dirty way to accomplish this, but it *could* work if you're willing to put up with some inconveniences... I'm picturing a battery with external cell connectors, where you could tap into one of those instead of boring into the battery case . Running the 6 volt accessories off the battery alone would run 3 of the 6 cells down while the other 3 remained charged, and you would have to manually charge those with a 6 volt battery charger to bring them back up to the state-of-charge of the higher 3... but things would probably stay balanced if you only used the 6 volt accessories while the generator was charging.

I ran into this issue with 48 volt electric golf carts that had 12 volt headlights tapped into 2 of the 8 six volt batteries in the pack. The proper way to do this is to use a 48 to 12 volt converter to feed the lights and other 12 volt accessories, which pulled the power off all of the batteries equally. It was interesting how quickly the battery pack voltage became unbalanced when the carts were frequently used at night (it was at a large hotel/resort complex), and the range would drop precipitously until you manually charged the two deader batteries back up to the level of the other six.

[Big Dan]

Yep, it never ceases to amaze me how some folks will actually search for a more difficult or complex way to do something when the right way is generally easier, safer, and more reliable!

[altair]

If you need 12 volts just install a small 12-volt motorcycle battery in the trunk or engine compartment. They come in sizes as small as a cigarette pack, and for charging a phone you would only have to charge the 12-volt battery once every three months. The kids carry these small battery packs with them to recharge their phones and they only have to plug them in every 5 - 10 days instead of every day. Talk to any kid on the street and they will show you how it works. Or go to the electronic store and find a kid with half shaved head and earrings and he will be glad to show you.

[markindy]

Thanks to everyone for providing input. I suspect my friend never used it, because he didn't quite understand it either. I do understand the fundamental difference between an "inverter" and a "converter"....just using the words stamped on the unit. RadioRoy This is a model "PGPI-HC, Power Inverter for Positive Ground Systems", from a company called Custom Autosound. So clearly, this was intended to power a 12v audio system. After a lot of digging, I was able to find a copy of the owner's manual on the web (it seems the company themselves only provide support through their dealers). It says to bolt the unit to a metal (grounded) surface. Since it only has one red wire going in for -6v, and one red wire going out for +12v....how can it still use the same common positive ground? I haven't had to think this hard about simple DC electronics in a long time...it's making my brain hurt.

[Big Dan]

Like trying to figure out how to put that square peg in the round hole?