I need to convert a shop-vac...

[just Warren]

...from running on house power to running off a battery.

That is I need some sort of converter that will accept the plug that hooks up easily to a battery.

Any ideas?


Thank you.

[Declaration Day]

Do you mean a car battery?  You need an inverter.  They are available at any auto parts or department store, up to 400 or 500 watts, for about $30-40.  I'm assuming that's enough for a shop vac, but you'll have to check.  There are more powerful ones, but they cost more of course.

Here's an example:  http://www.amazon.com/Black-Decker-400-Watt-Inverter-VEC1046BD/dp/B000EJS97S

[roo_ster]

Give it some Jack Chick tracts...

[Gowen]

Check on the shop vac and see how many watts it needs, then buy an inverter that provides that much plus.  The inverter has a regular 3 prong plug receptacle.  You will need some deep cell batteries to provide power.  You can charge these up at home or rig them up to your car so that you charge them as you drive.  By the time you add up everything, you might be able to buy a used generator at a flea market or off craigslist, also try harbor freight.

[Leatherneck]

Warren, that will be a challenge. As DD said, you'll need a 12V DC-to-110V AC inverter. But here's the rub: Shop vacs are absolute power hogs. My full-size sears vac draws about 18-20 amps on startup and something like 12 amps running. So size your inverter according to your shop vac power draw, allowing 150% of the rated power (amps) for motor start. Hopefully this will ensure no damage to your new inverter (they aren't cheap). I'd use the smallest vac that will get the job done. Or a gas-powered leaf blower.

TC

[Brad Johnson]

Like LN said, large inverters are not cheap.  They are also notriously fragile.  Plus, something drawing that much juice will suck a car battery dead faster than you expect.  It might be cheaper long term, not to mention more convenient, to get a small portable generator.

Brad

[CNYCacher]

http://www.armedpolitesociety.com/index.php?topic=18787.0

[Firethorn]

Do you mean a car battery?  You need an inverter.  They are available at any auto parts or department store, up to 400 or 500 watts, for about $30-40.  I'm assuming that's enough for a shop vac, but you'll have to check.  There are more powerful ones, but they cost more of course.

Yeah, you'd better check, my shop vacs are 12+ amps.  A small one might work off an inverter, but FYI, AC electric motors are MORE sensitive to the nasty electricity produced by many inverters than computers and such which just turn it back into DC.

I'll echo that it's probably better to use a generator if you need a big vacuum, or a dedicated DC unit for a small one.

[just Warren]

Perhaps I should explain what I am looking to do...this might have made a good first post.

I need to suck up dirt and small rocks with a portable vac but I will not be near any power outlets.

I have plans in hand for a gas powered vac but would like something quieter and if I can avoid packing in gas that is a plus.

Since the vac itself need not be large capacity that means I can go really small with the canister but I do need something that is reliable and powerful enough to lift up to pea gravel and that I can get an hour or two of suckage before needing a recharge.

I've found some 12 volt car vacs that might do the job but I need a to be able to plug it into the power source, i.e. a battery of some sort. So, instead of a three-prong outlet I can go with something that accepts a car lighter plug.

So does the thing I am looking for exist?


Again,

Thank you.

[Azrael256]

You're going to need more than batteries to run a shop vac.  12A @ 120V is 120A @ 12V.  Assuming perfect conversion, which ain't gonna happen, you'll need roughly two of my car, running, to deliver the amps.  

Nothing that will plug into the lighter will have much power.  Those circuits are built for 150-200W, which is about enough to run a good coffee maker.  One without a built-in grinder.  Pushing the amps you'll need to power a vacuum of that size will require wiring more like your starter and less like your iPod charger.

Silly question, but had you considered a broom?

[seeker_two]

Considering the scope of your project, you'd probably be better off renting a vac truck...

http://www.vactruckrental.com/

[charby]

Perhaps I should explain what I am looking to do...this might have made a good first post.

I need to suck up dirt and small rocks with a portable vac but I will not be near any power outlets.

I have plans in hand for a gas powered vac but would like something quieter and if I can avoid packing in gas that is a plus.

Since the vac itself need not be large capacity that means I can go really small with the canister but I do need something that is reliable and powerful enough to lift up to pea gravel and that I can get an hour or two of suckage before needing a recharge.

I've found some 12 volt car vacs that might do the job but I need a to be able to plug it into the power source, i.e. a battery of some sort. So, instead of a three-prong outlet I can go with something that accepts a car lighter plug.

So does the thing I am looking for exist?


Again,

Thank you.

So what exactly are you wanting to do? Cleaning out remote cabins?

[Harold Tuttle]

[Gowen]

Are you doing some sort of mining?

[cfabe]

One note of interest is that many small power tools use universal motors that can run off of 120V AC or 120V DC. Typically this is handheld things like drills, circular saws, but I think most shop vacs use a similar motor. So if you happened to have 10 car batteries on hand, you could wire them in series and run your vacuum.

Otherwise I think you'll need a big inverter and a really big 12V battery if you want to run it for any ammount of time.

Or you could just use a broom.