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 phantom
Wolfsburg Wizard
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| posted on February 10th, 2010 at 07:32 PM |
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Reducing 12v to 6v
Hi all, I'm working with an early beetle that has had a majority of its electrics converted to 12v. I have kept the wipers and fuel gauge workings
as 6v and need to reduce the input for them.
I was always advised to put 2 ballast resistors in series to drop the voltage from 12v to 6v, I have done this and had a friend measure the current -
12v in, 12v out. They didn't change anything.
I was told that a more modern approach might be obtainable from Jaycar, went there this arvo after some kind of modern convertor. They searched their
database and shelves and found one suitable unit only - a small convertor that will reduce 12v down to a number of voltages (switchable), including
6v. Bingo!
Maybe not quite there, as I was about to modify it for fitment tonight, it states it will produce a maximum of 2 amps out the end. I imagine that
wipers and the fuel gauge will need more power?
To fit this beast I need to remove the existing plugs, so don't want to do this until I know it will work, otherwise I can take it back.
Any advice on either the power draw of these 2 items, or another non-expensive way or making 6 volt? Thanks!
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ian.mezz
Wolfsburg Elder
I never said, I could write or spell
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| posted on February 10th, 2010 at 07:52 PM |
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my car has old electric ceramic kettle elements as resistors and they work
You just take the rods off.
or you could just buy some resistors from a vw shop.
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ian.mezz
Wolfsburg Elder
I never said, I could write or spell
Posts: 3913
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| posted on February 10th, 2010 at 07:59 PM |
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these things
http://cgi.ebay.com.au/ANTIQUE-VINTAGE-ELECTRIC-JUG-KETTLE-ELEMENTS-&-PAR...
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Menangler
A.k.a.: Dave Becker
Custom Title Time!
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| posted on February 10th, 2010 at 08:02 PM |
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You don't have to worry about the fuel gauge it will work fine on 12 volts.
I use 2 ballast resistors for 6 volt wipers and they work fine, resistors will still show 12 volts coming out, but when you draw currect through they
will give resistance, heat up a bit and your 6 volt wipers will work fine.
Dave
FAHRVERGNUGEN;
Description of a pleasurable sensation,
Experienced when a car and it's driver are in mutual harmony, A unique driving experience, Pleasure, Satisfaction,
A feeling experienced by Volkswagen Drivers.
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68AutoBug
A.k.a.: Lee Noonan
Aircooled Master
Beetle Restorer - Experience over 138% - YIKES --
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| posted on February 11th, 2010 at 12:54 AM |
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| Quote: | Originally
posted by phantom
Hi all, I'm working with an early beetle that has had a majority of its electrics converted to 12v. I have kept the wipers and fuel gauge workings
as 6v and need to reduce the input for them.
I was always advised to put 2 ballast resistors in series to drop the voltage from 12v to 6v, I have done this and had a friend measure the current -
12v in, 12v out. They didn't change anything.
I was told that a more modern approach might be obtainable from Jaycar, went there this arvo after some kind of modern convertor. They searched their
database and shelves and found one suitable unit only - a small convertor that will reduce 12v down to a number of voltages (switchable), including
6v. Bingo!
Maybe not quite there, as I was about to modify it for fitment tonight, it states it will produce a maximum of 2 amps out the end. I imagine that
wipers and the fuel gauge will need more power?
To fit this beast I need to remove the existing plugs, so don't want to do this until I know it will work, otherwise I can take it back.
Any advice on either the power draw of these 2 items, or another non-expensive way or making 6 volt? Thanks!
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- [size=4]Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY--- [/size]
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Uber Kafer
Wolfsburg Wizard
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| posted on February 11th, 2010 at 03:30 PM |
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Basic rule for selection of a ballast resistor to drop 12 volts to 6 volts is to have a resistance in series that is equal to the resistance of the
load (ie wiper motor), so you will drop 6v across each load. 6 + 6 = 12. Most resistors end up being around 1 ohm at 10 or 15 watt power-handling
rating.
The problem with ballast resistors is that unless they are exactly matched to the current draw of the load its only a guesstimate.
In order to identify the ideal resistance one trick is to put a hefty light globe in series, say 50 watt 12 volt headlight globe and turn on your
wipers. If wipers too slow put in a 65 watt globe (the globe wattage is not the same as resistor wattage in the top example) and swap and change
globes till you get the speed result you want. If nothing else, the headlight globes are a very convenient high-power-handling ballast resistor to
help find the ideal resistance to put in series with your wipers or whatever. Some people even end up with a headlight globe permanently mounted
behind the dash, but you still need to make sure nothing is close enough to be heat affected.
Otherwise, Wolfsburg West are selling the replacement armature for converting 6 volt wipers to 12v operation. I recently bought 2 as they were about
$35 each landed here in Aust.
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phantom
Wolfsburg Wizard
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| posted on February 11th, 2010 at 09:08 PM |
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Thanks all, I'll try them out in the next few days and see how they go, may revisit these ideas and replies if need be. I appreciate everyone's
time!
Bruce
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 matberry
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| posted on February 11th, 2010 at 09:55 PM |
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Go the new armature. The ballast resister or bulb is only just sometimes acceptable. The problem is the load on the motor is variable due to the
amount of friction/rain on the window, how fast the car is driving and the condition of the wiper blades etc etc. Even getting them to self park AND
maintain an acceptable speed can be challenging to say the least. There are also voltage reducers available but reliability can be an issue IMO.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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