# Little motor questions



## auto.pilot (May 9, 2012)

I picked up this F150 wiper motor for use with a home built power hacksaw. As a test, I used a 12v batter charger on a 10 amp setting. With power to the blue wire, it runs at about 70 rpm. Slower w the white wire. The hacksaw ideally will need more speed.  How many amps can this handle? There are no marking on it.  I think the truck's fuse is 15a.  

http://i1091.photobucket.com/albums/i383/jim7485/wiper motor/6eb96f98.jpg

Thanks in advance. Jim


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## Tony Wells (May 9, 2012)

Devices only draw what they need, based on load, resistance and inductance. You would see a spike in the current draw if you stalled it out, for example. Amps don't "push", they are a measure of device power draw. If the original circuit was fused at 15 amps, it shouldn't be allowed to draw over that much. Less is better. Also, your battery charger is not true DC. To advance your test, use a lead acid 12 volt battery hooked up the same way as if to charge, then wire the motor to that. The battery will smooth the current closer to DC.


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## DMS (May 10, 2012)

Something to think about if you plan on using this for a power hacksaw is that even at 15A (probably way more than that motor will sustain for more than a minute or two), that is only going to give you about 1/4 hp (15A*12V=180W 180W/750W=0.24Hp). That's not a huge amount of power. You may get it to work, but it's gonna take a while to make it through a piece of steel. You may want to plan for a larger motor up front.


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## Tom Griffin (May 10, 2012)

Jim,

I don't think the wiper motor will be adequate for your application. You might check *Surplus Center* for an AC gearmotor. That would probably be more appropriate.

Tom


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