6 volt wiper motor run on 12 volts

[gramps1951]

My 1951 b3b  came with a vacume wiper setup years ago I had installed an old power window motor about 25 years ago well it died and I have come across the right 6 volt motor can I run it on 12 volts or will I fry it . this old wiper motor I tested on 12 volts just to see if it would work worked fine but didn't dare run it long. thanks for any info. Is there any maintance I should do before I install thanks Neil.

[ggdad1951]

it will run...FAST!  And likely burn out.  There are 12V kits out there you could get a motor from and not worry about torching the motor (and potentially the truck).

[NiftyFifty]

Should be able to get a (drawing a blank...Resistor???) like a lot of guys use for the stock fan motor when they convert.  I had one in mine, but changed everything over to 12volt so it got tossed.

[NiftyFifty]

Here is what your after, I didn’t realize it was still in my junk drawer

[Plymouthy Adams]

16 hours ago, NiftyFifty said:

Should be able to get a (drawing a blank...Resistor???) like a lot of guys use for the stock fan motor when they convert.  I had one in mine, but changed everything over to 12volt so it got tossed.

 

think small as in...………………... RUNTZ

[DJ194950]

Runtz resistors are perfect for low amp draw like gauges but for much higher draws in continuous duty they burn up in a blink of the eye.

 

Other have suggested 2- 1 ohm resistors hooked in parallel with 6 volts tapped off the connection between the two resistors. First one gets 12 volt source from the other end and the other free connection on the second resistor goes to ground. This setup should be good for about 15 amp. continuous draws. The resistors are about 3/4" wide by 3" long and should be mounted to a plate of aluminum as a heat sink and mounted as available spots allow.

 

A internet search for 12v. to 6 volt automotive use will show some good drawings.

I would draw one but I am computer retarded! No kids close by to show the old man!  ?

 

DJ

 

 

[NiftyFifty]

fan Motor on high likely draws as much as a wiper motor, and I never had any issues with this resistor. 

[maok]

The wiper motor probably draws up to 5 amps (just a guess here) depending on how smooth the mechanical action is and the resistance from the wiper blade on the screen. The little hotrod style wiper on my '28 screen only draws 2 amps.

 

You would need a resistor/s that is fairly large in its power dissipation (wattage). The one pictured in post #4 would be more than capable, being 55 watts.

[bosworth]

I went through this with my 51 B3B.  I measured the current draw of the wiper motor, heater fan and horn.  I did this by connecting the motors, one at a time to a 6 volt battery in series with an inexpensive Harbor Freight multi meter on the AMP scale.  I found that the current draw of each motor was about 6 amps.  Since I wanted to drop 6 volts I connected each motor in series with  1 ohm resistors similar to https://www.ebay.com/itm/1-Ohm-100W-Watt-Power-Aluminum-Shell-Resistance-Shell-Case-Wirewound-Resistor/302391738234?epid=1593151861&hash=item4667f3bf7a:g:NOMAAOSwfjRZ5azf

I mounted the resistors to an aluminum heat sink.  If my calculations are correct,  6 amps flowing through a 1 ohm resistor will drop the voltage by 6 volts,  the heat generated in each resistor should be 6 amps times 6 volts which is 36 watts.  In reality I find that the 6 volt fan and 6 volt horn work fine but that the 6 volt wiper motor runs to slowly and with little power. I'm planning to try connecting a second 1 ohm resistor in parallel with the wiper motor resistor which should give me 1/2 ohm and a 3 volt drop.  If you would like I can take a picture of the resistors and heat sink.

Bill

[maok]

13 minutes ago, bosworth said:

I went through this with my 51 B3B.  I measured the current draw of the wiper motor, heater fan and horn.  I did this by connecting the motors, one at a time to a 6 volt battery in series with an inexpensive Harbor Freight multi meter on the AMP scale.  I found that the current draw of each motor was about 6 amps.  Since I wanted to drop 6 volts I connected each motor in series with  1 ohm resistors similar to https://www.ebay.com/itm/1-Ohm-100W-Watt-Power-Aluminum-Shell-Resistance-Shell-Case-Wirewound-Resistor/302391738234?epid=1593151861&hash=item4667f3bf7a:g:NOMAAOSwfjRZ5azf

I mounted the resistors to an aluminum heat sink.  If my calculations are correct,  6 amps flowing through a 1 ohm resistor will drop the voltage by 6 volts,  the heat generated in each resistor should be 6 amps times 6 volts which is 36 watts.  In reality I find that the 6 volt fan and 6 volt horn work fine but that the 6 volt wiper motor runs to slowly and with little power. I'm planning to try connecting a second 1 ohm resistor in parallel with the wiper motor resistor which should give me 1/2 ohm and a 3 volt drop.  If you would like I can take a picture of the resistors and heat sink.

Bill

 

You need two resistors connected in SERIES and tap from the centre connection of the resistors to drop the voltage of the 12 volt supply to 6 volts. 

 

[bosworth]

as I understand it, this series voltage divider should give you 6 volts at the junction of the two resistors when the motor is not turned on and will put a constant 6 amp load on the battery.  Once the motor is turned on the current should increase through the first resistor to at least 8 amps dropping the voltage at the junction to about 4 volts.  I'm thinking that this would make a good experiment.