# wiper motor question



## BIGANT (Jul 13, 2010)

ok so last year was the first time I made a prop using a wiper motor. I bought one from fright props along with a 5v power supply because I needed a nice and slow movement for my tombstone popper. I put the power supply in a water proof box behind the motor to keep it dry in the Florida weather. The prop only lasted about 5 days of running for a few hours each night. The power supply got so hot it melted the plug. Now keep in mind this was a rather large box I put it in, its not like it hard pressed for room. So I bought another power supply only to realize the motor had fried too so I had to buy a second motor as well. So as not to take a chance I only put the popper out on the big night itself. Even still after only a few hours of running the power was pretty hot. 

My question what kind of life expectancy should I expect from these motors and power supplies? What are you guys getting out of yours? Should I avoid using the 5v power supply and just use a 12v with a picovolt? It almost seems as if the 5v power supply struggles to keep the motor moving. Also the fixture its lifting for the tombstone popper weighs almost nothing, its a piece of pvc pipe with a foam skull on it.


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## Lunatic (Oct 3, 2006)

Wow BigAnt, that stinks. I never have problems with the 3 wiper motors I use. They are work horses and have lasted years. They are built for automobiles and they are supposed to last years. Surprised to learn that one burnt out. Maybe there is too much load weight on the motor??

What is the amp rating for the power supply? Those motors prefer something closer to 3-5 amps. I ran my kicking legs prop on a 1.5 amp power supply and it over heated too many times and then stoped working until it cooled down. I have since then switched to power supplies from a pc. They always have enough amperage to keep the motor strong and happy.

Another great thing about pc power supplies is that you have 3 choices for power...12 volts, 5 volts and 3.3 volts. That is how I control the speed of my props. I usually use 3.3-5 volts. The amperage is high enough on all 3 voltages. 

Otherwise I can't explain your problems. Maybe someone else has a good explanation.


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## Otaku (Dec 3, 2004)

Sure sounds like you had a low-amp supply in the mix. When the load (motor) asks for more current than the supply is rated for, it'll start robbing voltage to make up the demand. It's a vicious circle, with a burned-out supply being the usual result. I have used supplies less than 5A for wiper motors, but not much less, like 3.7A - 4A, typically. And they're used just on light load props, small rocking chairs and such. Can you post the amp rating on the supply you were using?


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## Abunai (Oct 28, 2007)

Do I understand correctly that if you want slow down a wiper motor, you can either use a lower voltage power supply, or use a standard 12v power supply and a PWM motor controller?
The difference is that if you lower the input voltage you lose torque, but with a motor controller you don't lose torque?


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## Otaku (Dec 3, 2004)

Yes, that's correct. Be sure your PWM controller, like this one:

http://electronickits.com/kit/complete/motor/CKMX067.htm

is rated for enough amperage to prevent burning out under load. The one in the link is good for 30A DC, so you would be good to go.


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## BIGANT (Jul 13, 2010)

I bought everything directly from frightprops so I bought the 5V5A power supplies they sell on the site to go with the wiper motors. Do you guys run your props every night during the month or just on the big night itself?


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## BIGANT (Jul 13, 2010)

here is a link to the power supply I bought from them

http://www.frightprops.com/electric-motors-1/power/5v-5amp-motor-power-supply-0955-0005-5000.html


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## Otaku (Dec 3, 2004)

Strange, that supply shouldn't have fried. It looks to be the same or very similar to the Monster Guts 5VDC supplies that I use. Even the low-amp (5V, 3.7A) wart that I use on my rocking chair doesn't heat up after several hours of running the motor.

Does the supply warm up or overheat when running the motor in a no-load condition?

Can you check the current draw of the motor/supply combination that caused the overheat failure?

The only time I've had this sort of thing happen was with a small DC gearmotor that blew a field coil. The motor still worked, but after about 30 mins of no-load operation both the supply and motor were too hot to touch.


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## littlepriest01 (Mar 20, 2010)

I too have had the same issue. I bought mine from monsterguts with the included power supplies, and it crapped out after a few hours, it also had a crack in the motor shortly after use. It didn't get dropped or anything like that, so I'm not sure what was wrong. I was using it to power the ghosts here:


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## BIGANT (Jul 13, 2010)

I can try to take everything out this weekend and grab my volt meter to measure the draw. I cant imagine there will be a big different with load or no load because as I mentioned the piece its lifting is very light perhaps half a pound at the most. I will try to measure the voltage both with and without a load. 

So should I expect this thing to work night after night for hours on end or is that asking too much? Do I need to save my animatronics for the big night only?


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## Otaku (Dec 3, 2004)

Good question, actually. The only wiper motor props I have that run constantly are my dead kid in the rocking chair and the witch's cauldron. I run them on either the 5A or the 3.7A supplies. The motors don't seem to care; I don't notice any reduction in speed or torque, but these are pretty light loads. My other wiper motor prop is intermittent, a nearly vertical coffin that opens and closes it's lid, again a fairly light load.


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## BIGANT (Jul 13, 2010)

Do you run them every night for the entire month or just for the night on Halloween?


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## Otaku (Dec 3, 2004)

Just for the night, total time is like 7-8 hours. I still can't see how a power supply would melt down like that. Do you check the props for binding and free movement each day? Maybe the load became too great for the supply to handle.


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## tstraub (Feb 26, 2012)

I would add an inline fuse on the DC side of the power supply. that way if it does bind and the current goes sky high the fuse will hopefully blow and stop the current before the power supply fails.


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## dazgill (Aug 7, 2012)

the only problem i have ever had with a wiper motor was when testing a stirring witch with a 12v 1amp power supply. it ran ok, but then blew after about 15mins.

(as a side story, the power supply blowing tripped the electric supply to the garage at the fuse box in the house. The garage door is electric and i had no phone. so i was in total darkness, surrounded by many zombies, witches etc etc and couldn't get out. the wife thought i was testing something so didn't come out to check! after a while i managed to feel my way to the auto door release!!)

using a PC power supply i have not had a problem. i have a few props that run continuously and some that are intermittent, some of the props are quite heavy but the motors continue on.

i would check that something was not binding the prop and hence binding the motor and that would cause an overload to happen


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## Jack Is Back (Jun 21, 2011)

I've used wiper motors to run props continuously (pendulum on my GF clock) and intermittently on other props and havn't burnt out either the power supplies or motors. The clock runs on a PC PS but my other wiper motor props have run off 5 and 12 volt supplies from Monster Guts and have never melted anything.

It's alway possible you just had a bad PS from FP.


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## Thisaintmayberry (Aug 23, 2010)

I run a heavy FCG and an Axworthy ghost also fairly heavy, with wiper motors powered by ATX computer power supplies. I use the -12VDC (yellow) wire and slow the motors with PWM speed controllers similar to the kits mentioned. They have run every year for 10 or so consecutive nights without fail. These are all scavenged parts.

Assuming nothing is defective, I can only suggest switching to a high amp 12VDC power supply and use a PWM speed controller to slow it down. I use this one.


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