# Converting AC to battery power?



## weaz (Sep 11, 2010)

Can anyone give me a formula on what batteries would be needed to run a typical 12V vent motor for a prop? This is something that will not be near an electricity source, but there is room inside for a configuration of batteries. I just don't know what to use. I was hoping to use C's or D's instead of a large 12V battery like is in a power wheels kids vehicle.

TIA


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## David_AVD (Nov 9, 2012)

Using a 12V SLA (Sealed Lead Acid) battery would be much cheaper in the long run I'm sure. You can get them in various shapes and capacities.

Some examples:


 12V 1.2 AH SLA 97mm x 57mm x 43mm
 12V 2.9 AH SLA 106mm x 78mm x 56mm
 12V 4.5 AH SLA 110mm x 90mm x 70mm
If the motor draws 400mA (0.4A), in theory the 1.2 AH SLA will run it for 3 hours (1.2 AH / 0.4A = 3 Hours).

Maybe someone can chime in with the typical (loaded) current draw of these motors?


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## halstaff (Nov 18, 2009)

1.5V per cell so 8 batteries. 
Here's one to check out - http://www.mouser.com/ProductDetail/Eagle-Plastic-Devices/12BH181A-GR/?qs=sGAEpiMZZMupuRtfu7GC%252bR2lfMmZjxjt9q01oUfqCWg%3d


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## tstraub (Feb 26, 2012)

You could also use 2 x 6 volt lantern batteries. I believe they will last longer than D cells and since they have the spring terminals on top you could use simple alligator clips to make the connection and skip the battery holder.

Tyler


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## The_Caretaker (Mar 6, 2007)

batteries only put out 1.5 amps, if you need 3 amps you would need 16 batteries, two sets of eight in series and then the two sets in parallel to give 12 volts @ 3 amps, if you need more amps yuo will need to add addition 8 battery sets


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## pshort (May 6, 2008)

Fwiw, I think Amazon.com: 12VDC 4RPM gear motor designed to operate a vent in a Chrysler product.: Everything [email protected]@[email protected]@http://ecx.images-amazon.com/images/I/[email protected]@[email protected]@31fTyDPiWKL are the vent motors in question - this listing says the stall current is 200 mA.


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## RandalB (Jun 8, 2009)

I used sealed Lead Acid batteries to power both a rocking chair prop and Clown Blast horns last year. A 12v 5AH battery cost $15, came with a charger and powered a wiper motor based prop for almost 6 hours. This year, I'll get the 10AH ones for $10 more...

I think they'd run a vent motor for a couple of days with no problems. 

HTH,
RandalB


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## bert1913 (Oct 27, 2011)

http://www.halloweenforum.com/halloween-props/115073-vent-motor-9v-battery.html


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## weaz (Sep 11, 2010)

Thx Guys! Randall, where did u buy that battery? 
and one last question, but will going over in amperage Ruin the motor?


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## stagehand1975 (Feb 22, 2010)

you have a better chance of damageing the motor by going under amps. when you see an amp rating on an item, it is the amount of current required to run that item as it was designed to. running that item with less than what it need can overheat it and the power supply it is connected to. any amps more than what it needs is just gravy. its the voltage that will damage it if you go over.


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## David_AVD (Nov 9, 2012)

The motor will draw the same amount of current (Amps) from the power supply (or battery) even if the supply is capable of much higher current.

The power source does need to be able to supply at least what the motor requires of course. eg. You can't drive a motor that requires 2 Amps from a 1 Amp power supply.

Using an SLA battery will work out far cheaper than dry cells, even for only a few runs.


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## weaz (Sep 11, 2010)

You guys and gals are all awesome! Thx for all your help!


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## RandalB (Jun 8, 2009)

weaz said:


> Thx Guys! Randall, where did u buy that battery?
> and one last question, but will going over in amperage Ruin the motor?


I got 'em off Ebay. They had free shipping too as I recall...

They worked well for my "Spark Weapons" project too..

RandalB


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