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# 2 6v batterys make 1 12v??

#1
04-24-05, 09:10 AM
Gotchesum
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2 6v batterys make 1 12v??

Here is my delima...I have an early car with a 6v power top motor...can not be converted to 12v...like the rest of the car...can I run 2 6V batteries in series, and run my PT motor off of 1 of the batteries, and the car off of both...? Will it charge both Batts...?

Thanks

#2
04-24-05, 01:01 PM
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You have a 6 volt vehicle and want to install 2 6-volt batteries instead of one? You can do it, and if done correctly, the generator (usually on 6 volt vehicles) will charge both batteries.

Just curious what kind of car because I've never heard this discussion without it being an old tractor.

If your suggesting you want to convert the rest of the car to 12 volts ( i.e. two 6 volts in series), there are other items required. Wait to hear your reply.

#3
04-24-05, 02:41 PM
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A 6 volt motor can be run on a 12-volt system with the proper resistor
There's no quick and easy solution, but it can be done

I'm really not Mr. Electric, but I did research it (I've had a few)
I'm sure someone with a better grasp can be more specific, but here goes:

Because the amperage determines the motor speed, that's what you reduce
You connect an ammeter in series with the motor when it's running on 6

R = E/I (or "ohms = volts/amps")

If you're 1.5 amps @ 6 volts thats 4 ohms (6/1.5=4)

That means 1.5 amps @ 12 volts = 8 ohms (12/1.5=8)

You need a 4 ohm resister

Watts = volts X amperes
W=12 X 1.5 = 18 watts

That means you need a 4-ohm, 18-watt resistor

...I am also curious as to the car
I have a Pontiac Deluxe now, it needs alot of work
I may need to convert it just because not much is usable on it, so very little can/will remain original

#4
04-24-05, 03:36 PM
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Are you going to be using a 6V or 12V generator? I would assume that if everything except the PT motor will be converted to 12V, you'll need a 12V generator, so it would make sence to get a 12V battery and use a resistor for the motor that slickshift talked about.

#5
04-24-05, 04:09 PM
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I'd check into

replacing this motor with a 12V motor. Power window motor? If this can't be done, then maybe talk with an electrical shop, motor rebuild shop, etc and see if this motor can be re-wound for 12V.

Trying to help!

#6
04-24-05, 04:15 PM
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Originally Posted by Desy2820
replacing this motor with a 12V motor. Power window motor? If this can't be done, then maybe talk with an electrical shop, motor rebuild shop, etc and see if this motor can be re-wound for 12V.
It's pretty common to put 12V "guts" in the 6V "case"
The motor must be pretty unique not to be able to do it

#7
04-25-05, 12:39 AM
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Originally Posted by slickshift
That means you need a 4-ohm, 18-watt resistor
Slickshift, yo da man!

#8
04-25-05, 07:09 AM
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You can also get 6 volts out of a 12 volt battery. A 12 volt battery is essentially six 2-volt cells connected in series = 12 volts. The cells are connected by straps or terminals in the top of the battery and if you locate the right spot (essentially in the middle, but near the edge of the case) you can tap in by drilling a small hole in the right spot and running a screw down into the strap/connector. Don't laugh, it works! My dad showed me that trick around 1970 or so. Had my first car, a 1966 A-H Sprite, and used a portable cassette player as my "sound system". Only problem was using a lot of batteries (it held 4; 1.5x4 = 6 volts). So he showed me this trick and I had a ready supply of 6 volts.

TG

#9
04-25-05, 08:07 AM
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You have it right, 2- 6v batteries in series, tap one for 6v. they will both charge with the 12v alt or generator. This is done all the time on Motor coaches,2 huge 12v batteries in series to run the Coach 24V systems, they tap one to run the 12v stuff, usually electronics.

#10
04-25-05, 02:15 PM
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Originally Posted by the_tow_guy
You can also get 6 volts out of a 12 volt battery. A 12 volt battery is essentially six 2-volt cells connected in series = 12 volts. The cells are connected by straps or terminals in the top of the battery and if you locate the right spot (essentially in the middle, but near the edge of the case) you can tap in by drilling a small hole in the right spot and running a screw down into the strap/connector.
Taping the 12 volt Battery for 6 volts. Don't do it!

When battery's are charging they produce some hydrogen gas.
If this screw taping inside the Battery gets loose or corrodes off and makes any sparks inside the battery,
The hydrogen gas may ignite and explode the battery.

Drilling holes in the "straps" will reduce the current capacity of the "strap" making a hot spot inside the battery.
Like installing smaller battery cables.

#11
04-25-05, 10:10 PM
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Originally Posted by slickshift

I'm really not Mr. Electric, but I did research it (I've had a few)
I'm sure someone with a better grasp can be more specific, but here goes:

Watts = volts X amperes
W=12 X 1.5 = 18 watts

That means you need a 4-ohm, 18-watt resistor
The wattage calculation should be.

Watts = volts X amperes
Watts = 6 volts X 1.5 amps = 9 watts
The voltage across the resistor would be 6 volts not 12 volts

With the proper resistor it would create a voltage drop.
6 volts across the motor and 6 volts across the resistor.

9 watts would be the amount of power the resistor will use / dissipate.
The resistor will need to have a wattage rating higher then 9 watts.
The resistor can get hot, But that's only when you run the motor, it may not run long enough to generate any heat from the resistor.

Or,
If you get a second 6 volt motor and wire it in series with first motor.
BUT both motors must be rated at the same current/amps and voltage.
If your motor draws 3 amps @ 6 volts the second motor must be a 3 amps @ 6 volt motor.

I think your motor will draw over 3 amps, something you will need to measure before doing anything.

#12
04-26-05, 12:57 AM
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That particular example I gave is correct for this application
That's good point that the resistor wattage can/should be higher
I should have wrote "...minimum 18watt resistor, 20 or 25 would be best"
I also should have wrote "I've had a few 6-volt cars" instead of "I've had a few"
Har har

My point was not to lay out instructions, but to back up my statement "There's no quick and easy solution, but it can be done"

Gotchesum is probably getting that by now

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