Ballast Resistors

phantom Wolfsburg Wizard

598 posts · joined Mar 2004 · 9 Sep 2006, 12:38 pm

#532394

Can someone give me some advice on Ballast Resistors?

I am doing a semi-12v conversion of a beetle, keeping the 6v starter but going to 12v genny / stand, regulator, coil, battery, bulbs.

I have had a number of people tell me to keep the 6v wipers / horn / fuel gauge, and to step the power down using 2 ballast resistors. Well, I have ém (under good authority that I have the right ones), but there are no instructions or documentation with them. they look like a ceramic rectangle, wire on one end, connector on the other. Can they be fitted either way, or are they 'direction specific'? Will 2 of them bring the volts down from 12 to 6?

Thanks!

www.canberravw.com

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 · 9 Sep 2006, 12:57 pm

#532398

First off, Yes You can use them either way round...
I just used one on My Son's 56 12 volt beetle for the wipers...

No, they don't change 12 volt down to 6 volts...

they are just a resistance....

Horn may be OK on 12 volts otherwise change it...
I think they draw too many amps for the ballast resistor..

Lee

- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 · 9 Sep 2006, 1:02 pm

#532399

Hi,
I only used one resistor for My sons' wiper motor...

I haven't tested them...
but there is probably more than 6 volts coming out the other end...
as wipers do go a bit faster...

I'm not sure whether Your Radio or fuel gauge could take
the extra voltage....
although Many people used 8 volt batteries back in the 60s & 70s...

I'd try two ballast resistors in series for the radio & fuel gauge...

cheers

Lee

http://community.webshots.com/user/vw68autobug

- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

phantom Wolfsburg Wizard

598 posts · joined Mar 2004 · 9 Sep 2006, 1:07 pm

#532400

Thanks Lee....so, they don't reduce the volts, but just cut the output? As in, 12 in, 6 out?

Might try the horn on 12v, will run the power for the wipers and gauge through the resistors.

Radio is already 12v, was upgraded through a 6-12v invertor.

Maybe I should run power for wipers off first invertor, and then run gauge off the second resistor?

Thanks, glad to hear they are not directional. You obviously found them to work OK? They don't heat up too much?

www.canberravw.com

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 · 9 Sep 2006, 2:08 pm

#532407

Hi
Well, I've never actually checked them...
they may get hot with the wipers....
but thats why they are mounted on ceramic, so they can get hot...
You will also need one for the electromagnetic cut off valve on the carburetor... [green in the pic]
its labelled incorrectly, as its a cutoff valve]
You can pick up 12 volt ones of these at any swap meet etc so long as they are the same...
or You may have a 1600 engine with 12 volt cutoff valve and 12v auto choke..
or You could run these thru a single resistor...

the horn should be OK with 12 volts...
it will vibrate a lot more and probably make a different sound... but 12v horns are also easy to come by at swap meets... but I wouldn't try a resistor with the horn...
it would be like a short circuit to the resistor..

the resistors offer a resistance to the power going thru them so it depends on how much the device uses to how much voltage comes out the other end...
most old falcons used these, so they can be also picked up
easily... & I've never come across a burnt out one...

Everything was changed on My Son's 56 beetle to 12 volts excepting the wipers... mainly as He couldn't find another assembly that suited the holes in the body...
plus He was in a hurry to finish it,...

1968 only - wiper arms have a grub screw to screw them onto the round shaft.. then You can fit late model wiper blades... You may have to trim the blades slightly for length...

Lee

http://community.webshots.com/user/vw68autobug

[ Edited on 9-9-2006 by 68AutoBug ]

[ Edited on 9-9-2006 by 68AutoBug ]

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- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

tassupervee That really hurts doesnt it!

1,171 posts · joined Sep 2003 · 10 Sep 2006, 11:51 am

#532627

Yer what he said M8.

However, without actually knowing the current draw (in amps) of your radio, just adding resistors in there may not reduce the voltge sufficiently to keep the radio alive. The voltage to the device will vary depending on the load on the circuit so you really need to test your radio with a multimeter to find the current draw and then work out the resistance required to drop the voltage to a safe level.

For that job done properly and reliably, you need a voltage reducer (regulator).
if you have some electronics savvy, or know somebody who does, you can make one very easily and cheaply. It depends on the current draw of the radio at full blast but you might be able to get away with a simple flat pack "78**" series voltage regulator mounted onto a metal dash component as a heat sink.
otherwise you might have to use one of these regulators to bias a 2N3055 power transistor which will give you a reliable 5 amp continuous regulated supply.

This sound fairly exxie and complicated but when you see how its done its very simple.

The bits are available at Jaycar/Tricky Dickies for just a few dollars and details of the wiring are in the "Data" section of their catalogues.

Otherwise, you might be able to buy something from a automotive sparks or audio fitter.

Im not a complete idiot, quite a few parts are missing....

mackaymanx Custom Title Time!

1,611 posts · joined Jan 2006 · 10 Sep 2006, 12:00 pm

#532630

For the fuel gauge try a 6volt Zener diode. I used 2 in parallel on my brothers Split kombi when he went to a 12 volt system

Quote of the week
"Do I wish to send them to you again, nope, no interest can't be bothered really, to much hassle for little or no return."

[IMG]https://www.vw-mplate.com/mplate2-18600.png[/IMG]

OZ Towdster Keen to finish some projects

1,921 posts · joined Dec 2003 · 10 Sep 2006, 3:26 pm

#532675

We changed our beetle from 6 to 12 four years ago and you do NOT have to change anything in relation to your Fuel guage or sender and or your horn .
For your wipers i would recomend 2 balist resisters in line to slow them to the original speed as with one only they run too fast and at time will not stop !!!!
To wire up just remove the incoming power from the wiper switch and plug into one resister then using a short piece of wire and connections connect one resister to the other then from the other end of the second resister to the wiper switch where you pulled the original wire from.
One final note is to make sure you mount the resisters as was previosly mentioned they will heat up after a while when wipers are running , as it sounds like you are doing this to an early Beetle i would recomend mounting them ( while making sure the coils are isolated )to the front side of the wiper motor brace.
The only other thing you need to cosider is the starter motor , now they will quite happily do the job they do turn quite a bit faster than before and this will over time chew the side of the flywheel resulting in horid screams when attepting to start but you CANNOT just fit a 12 volt starter in conjunction with a 6 volt fly wheel.
Hope tis all helps out you r problems , by the way if you r flywheel is OK then you will get approx 2 years out of an every day driver before the horid screams start
Catcha Andrew Any questions ring me on 0407373781

Don't let body work get in the way of real suspension travel

Dasdubber DAS Resto Haus

5,746 posts · joined Aug 2002 · 10 Sep 2006, 9:00 pm

#532786

Yep as Andrew said above I too used two ballast resistors (1.6ohm from memory) in line to resist the input to the wiper motor of my old ragtop. On my bug prior to the ragtop I used to use the starter and horn (6V) with the 12V system without problem.

We put two ballast resistors in line for my brother in laws ghia but the wipers were way too slow so we just removed one and voila - works well now and turns off when told to!

www.dasrestoparts.com.au