Wiper Motor 6v to 12v

[belvedere666]

My ‘50 has been completely re-wired using an EZ harness.

The car is now 12v negative ground.

i have the original vacuum wiper motor in the car now.

I came across an electric wiper unit from a ‘51.

pretty sure it’ll take a little creativity to mount it the car, but wiring it to my 12 volt system has me baffled.

i picked up a reducer. One of those gold colored ones with the aluminum heat sink.

i was told it would work better than the smaller Runtz reducers.

 

Bench testing straight to my 12v battery, with a wire from the wiper motor grounding strap to the negative post on the battery, I get power and the motor moves.

i can hook it to a wiper switch, not stock, and get the same results.

 

once I put the reducer inline either before the switch, or after, and attach the wiper motor wire, the motor grounds out and doesn’t want to move.

 

i can get a reading of 12v off the end of the reducer and as soon as the wiper wire touches it it drops down to under 1v.

 

I don’t know much about auto electrical stuff, but I’m guessing that since the motor was originally positive ground and now it’s being grounded to the negative, when it touches the positive, it’s grounding itself.

is there any way to rectify this?

reverse the ground inside the motor?

The wiper motor has two wires.

the wires are old and faded but it looks like the thick one is black and the thin one is green.

 

any advice? troubleshooting recommendations? 

 

 

[DrDoctor]

Belvedere666,

   I’m certainly no electrical expert, altho’ I’ve wired/rewired my share of cars in my time, I’ve wired motors with both – and + grounds in + ground cars, and never had a problem. Radios, for example, are ground-sensitive. I know a – ground radio connected to a + ground system will fry, as I’ve got a fried lump on my garage floor that was once the radio from our ’46 Plymouth Special DeLuxe Club Coupe. But, electric motors are “ground indifferent”. Now, as to what’s causing your specific situation, I’m sorry, but I’m not much help. I tho’t is it’s something with the voltage reducer, but that just a SWAG. Good luck with this . . . Regards . . .

[DJ194950]

I found out that it takes two of those big resistors wired to together and a center tap wire to your motor to work, Why that works??

I do not know how to explain it nor really understand myself!

My good friend that does some electronics did his best trying to explain it to me.

 

Do a web search on 12volt to 6volt automotive wiring using resistors and you will see many diagrams on the how to's.

I have "somewhere"  a rough wiring setup my friend did for me.

I wanted this for the horns( dual) and the electric choke on my Ply. 50 4 dr.. Have not done this yet as they both work but seem to draw heavy amps and I am not really happy with that.

 

Happy hunting and wiring!

 

DJ

[belvedere666]

3 hours ago, DJ194950 said:

I found out that it takes two of those big resistors wired to together and a center tap wire to your motor to work, Why that works??

I do not know how to explain it nor really understand myself!

My good friend that does some electronics did his best trying to explain it to me.

 

Do a web search on 12volt to 6volt automotive wiring using resistors and you will see many diagrams on the how to's.

I have "somewhere"  a rough wiring setup my friend did for me.

I wanted this for the horns( dual) and the electric choke on my Ply. 50 4 dr.. Have not done this yet as they both work but seem to draw heavy amps and I am not really happy with that.

 

Happy hunting and wiring!

 

DJ

Something like this?

[DJ194950]

Yes that the way I was told.

 

The value of the resistors depends on the max amp load expected, I don't believe you can have it to high of a value, just not too low of they will burn out.

 

I bought 100 watt - 1 ohm which should be good for at least 30 amp max draw. About $3 each. delivered. They can be had online for about $1 each but you get to wait for them to be shipped from china- prepaid with only a credit card purchase- - Not for me, pay up front to get them from a US based seller with a great rep!

 

DJ

[dale]

Buy a 12 volt after market wiper motor.  Much less trouble .  Are you sure the 6 volt one even works ?

[belvedere666]

1 hour ago, dale said:

Buy a 12 volt after market wiper motor.  Much less trouble .  Are you sure the 6 volt one even works ?

6 volt motor was connected to a six volt battery and it worked.

[dale]

14 hours ago, belvedere666 said:

6 volt motor was connected to a six volt battery and it worked.

They use 8 volt batteries in 6 volt systems so maybe just a resistor they use on 12 volt systems ignitions that bring voltage down to 9 volts like on GM cars in the 50s would do.  Would changing the ground to negative cause the motor to run backward ?  Let us know how it works out.

[DrDoctor]

Reversing the polarity on the wiper motor will have no effect on the direction the motor runs.

[dale]

3 hours ago, dale said:

They use 8 volt batteries in 6 volt systems so maybe just a resistor they use on 12 volt systems ignitions that bring voltage down to 9 volts like on GM cars in the 50s would do.  Would changing the ground to negative cause the motor to run backward ?  Let us know how it works out.

Guess on wipers it doesn't matter which way the motor turns.  12 volt to 6 volt resistors are readily available.

 

[dale]

1 hour ago, DrDoctor said:

Reversing the polarity on the wiper motor will have no effect on the direction the motor runs.

 

 

Just now, dale said:

Guess on wipers it doesn't matter which way the motor turns.  12 volt to 6 volt resistors are readily available.

 

Be awfull if the wipers ran backwards.. LOL

[belvedere666]

10 minutes ago, dale said:

Guess on wipers it doesn't matter which way the motor turns.  12 volt to 6 volt resistors are readily available.

 

In the original post I said that I have a 12-6 resistor and it’s not powering the motor.

[DrDoctor]

Why not just buy a 12v to 6v voltage reducer – simple to use – 12v in and 6 out.

Edited March 23, 2019 by DrDoctor

[belvedere666]

11 minutes ago, DrDoctor said:

Why not just buy a 6v to 12v voltage reducer – simple to use – 6v in and 12v out.

 This is the second comment in a row, that mentions that I just need to use a 12 V to 6V reducer. The post mentions that I have a 12V to 6V reducer.

That is the reason why I posted. I am using the reducer, and it isn’t working.

[dale]

Check to see if you actually have 12 volts going in.

[Andydodge]

Electric wipers were the standard fitting in Oz mopars from the late 30's at least and when I converted my car, a 1940 Dodge to 12 volts in 1973 with the install of the 318 Poly I used a voltage resistor in the power wire to the wiper which worked fine for years, the only reason I ended up swapping the wiper motor out for a BMC cable system was that the stock splined "washer" fitting used on the original wiper towers were stripped and unobtainable in Oz in the early 1980's...........the cable wipers have worked fine since...............the voltage resistor or drop that I used is the same style that is used in ignition wiring , white porcelain with wire wound inside it.........worked then and the same style of resistor is still used on the original fuel gauge in the car and working fine.............andyd  

[pontiacguy]

I just converted my car (54 Plymouth) to 12V as well. I am working through the conversion too. As was stated, the motor is indifferent to the swap from positive to negative ground. The motor will ground through the case by way of a jumper strap that circumvents the rubber mount. The first thing you should be watching for is the motor speed. how fast is it going on 6 volts? How fast on 12V. It should run twice as fast at 12V than the 6. So first get it to work w/o the resistor. If it runs fine like that but not on the resistor then likely your resistor is knocking your power down to far to start your motor. Electrical power is current*voltage (P=IV) so your resistor may be burning off too much.

[ptwothree]

On 3/18/2019 at 2:35 PM, dale said:

Buy a 12 volt after market wiper motor.  Much less trouble .  Are you sure the 6 volt one even works ?

I'd like to know what 12 volt motor out of what vehicle will interchange with the stock 6volt.....

[maok]

On 3/18/2019 at 2:42 AM, belvedere666 said:

 

I don’t know much about auto electrical stuff, but I’m guessing that since the motor was originally positive ground and now it’s being grounded to the negative, when it touches the positive, it’s grounding itself.

is there any way to rectify this?

reverse the ground inside the motor?

 

 

 

 

You answered your own question, take it to a electric motor rewinder. May or may not be an economical proposition.

[Roger the Dodger]

I used one of those 12-6v resistors in the aluminium heat sink, on my 52 Dodge. Worked the wipers for the 3 years I had the car. No problems. Maybe yours is faulty.

[DrDoctor]

Su 17Mar2019 12:42p – “[sic] I picked up a reducer. One of those gold colored ones with the aluminum heat sink. i was told it would work better than the smaller Runtz reducers.”

 

Su 17Mar2019 09:37p –

 

 

 

Tu 19Mar2019 02:36p – “In the original post I said that I have a 12-6 resistor and it’s not powering the motor.”

Tu 19Mar2019 08:26p – “Why not just buy a 12v to 6v voltage reducer – simple to use – 12v in and 6v out.”

Tu 19Mar2019 08:38p – “This is the second comment in a row, that mentions that I just need to use a 12 V to 6V reducer. The post mentions that I have a 12V to 6V reducer. That is the reason why I posted. I am using the reducer, and it isn’t working.”

F 22Mar2019 01:15p 9(approx) – Yep, I did miss the remark about the reducer – sorry ‘bout that. However, please take note that your diagram of 17 March, 2029, that you refer to 2 resistors. Resistors aren’t the same as voltage reducers. Hence, the confusion. It appears as tho’ you’ve “switched horses in the middle of the race” – resistor or voltage reducer??? Well, I think that about covers this. Now, I’ll go back, sit in my favorite chair, eat some popcorn, and just watch the show . . . .

Edited March 23, 2019 by DrDoctor

[chrysler1941]

Although I don't understand the need to convert to 12v, the best way is to use a step down converter .

 

Using a resistor as a "reducer" or 2 resistors as a voltage divider is never good idea due to high amperage draw and heat.

Using two 1 Ohm resistors as shown above will draw over 12 Amps. This will be converted to heat, hot enough to melt surrounding Insulation.

A better way is spending $6 for a DC converter. Here is a link for a 15A converter. When connected you'll have to adjust to 6-7 volts. 

https://www.ebay.com/itm/DC-DC-15A-Buck-Adjustable-4-32V-12V-to-1-2-32V-5V-Converter-Step-Down-Module-DT/252586434129?epid=1684291373&hash=item3acf531e51:g:OKgAAOSwfpVZFFSw

 

If motor turns the wrong way, swap wires on brushes.

 

 

[DonaldSmith]

The diagram with two resistors in series does not make sense to me for an automotive circuit.  Presumably, with 12 volts between the battery and ground, 6 volts would be available at the juncture between the two resistors.  This is theoretically true.   For items in a series, each item contributes to the voltage drop, in this case totaling the 12 volts.   Equal items have equal voltage drops.   

 

Imagine two light bulbs in series.  If each bulb is rated at 6 volts, and their wattages are the same, and 12 volts is applied to the series, each bulb would take 6 of the volts and shine fine.  If a voltage meter is applied at the juncture between the two bulbs, it would register about 6 volts to battery, and 6 volts to ground, since the voltage meter draws negligable current.  In fact, I saw such a circuit to provide about 6 volts to an electonic device which did not draw much current.   

 

But draw an unequal load, and voltage drops are not equal.  Imagine two bulbs connected in parallel between ground and the juncture, and a single bulb connected to the battery.  The single bulb would get more than 6 volts and the two in parallel would have to share less than 6 volts.   Replace the two bulbs with a wire, and see how quickly the single bulb burns out. 

 

 I've forgotten how V=I/R works with watts and ohms, but I think if a motor were connected between the juncture of the two resistors and ground, the motor would get little voltage and the single resistor to the battery would get verrry hot.

 

 

Edited March 22, 2019 by DonaldSmith
typos; wattage, would

[DrDoctor]

   Wow!!! Thanks Chrysler1941, and DonaldSmith. You’ve both cleared up that nicely. I obviously wasn’t as confused as I tho’t I was. Now, I’ll just get myself an adult beverage, relax, resume sitting in my favorite chair, and watch the show. Warmest regards to you both . . .