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Novice needs volts/amp advice


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How many hundreds of cold cranking amps does a car battery provide?? He wants to power the windshield wiper motor with a low current AC/DC power supply. He said "it looks like" it pulls 6A when powered from a motorcycle battery. Did he look to the left side or the right side? Did his current meter drop 3V?


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The original poster's measured current draw sounds right on the money, according to these links. A running current of 5 amps seems reasonable but the starting current and stall current will be a lot higher than that. The first link has a lot of good information.

Wiper Motor Page - Scary Terry's Halloween Page

Wiper Motor Current Draw - Society of Robotics

One solution to powering the motor would be an X-Box power supply which can often be found at thrift stores for a few bucks. These beasties will supply 14 amps and some models even 16 amps! Here's a link to my efforts to figure out how to use these guys. In addition to the main 12v supply, there's also a low current 5v supply and a control wire that must be connected to 5v to turn the 12v output on. This may be useful for your app, as a low power switch or a microcontroller could be used to control the 12v output.

X-Box Power Supply - 12 Volts @ 14 Amps!

Ian Rogers

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If you look at the fuse in ANY motor vehicle, the wiper motor will be 20 / 30 amp... BUT!! that is for extreme load eg dry windscreen drag..

I do agree that the larger capacity PS will give you the results you need... The problem here is.. How much would you pay for a decent Power supply.
I would go for a 15A supply... If the motor is old and tired, the starting current will be even higher..


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Well, as I posted above, I would pay ~US$5.99 for a 14 - 16 amp XBOX power supply at a thrift store. These things are very common, and the few I have purchased at thrift stores have all worked perfectly. One of the links I posted by people who do all sorts of wonderous things with wiper motors even suggests this exact solution.

I doubt the original poster will be back anyway, with so many people telling him that this can't be done despite many examples otherwise.


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