Running small shop vac on inverter

Quickstep192

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Chesapeake
I use one of those cheapo Home Depot Bucket Head vacs to get water and crud out of the bilge.

The vac works really great, but dragging a long extension cord to the boat is a bit of a hassle. (First world problems, I know)

Using a clamp on ammeter, I determined that the vac briefly draws 6amps at start-up and a shade under 3amps while running.

Is it reasonably to think I can run this on a 500w inverter? I could just screw the inverter to the top of the vac!
 

DDW

Super Anarchist
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Since a 500W inverter is dirt cheap, try it and see. It is no doubt a universal motor, these can run on really crap power, even DC. The inrush current spike is probably larger than that (response of a clamp ammeter is very slow) but inverters are pretty good at feeding short spikes.

The main problem with your scheme is, don't you now have to drag a DC cord around?
 

steele

Super Anarchist
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Land of the locks
Pobably not. Too much load on start up, and even at 3 amps will probably overheat after just a few mins. The vacuum's load will also peak above 6 amps if the hose is occluded, like when you first put the hose underwater in the bilge. Keep in mind with that load you can't use a cigarette lighter plug and will probably need aligator clips directly to the battery.
A recharble wet dry vacuum (dewalt or similar) would be a lot better plan.
 

Quickstep192

Anarchist
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Chesapeake
I would use alligator clips and connect directly to the battery when in use.

The problem I see with the re-chargeable type is how long the battery can keep charge between uses.
 

Zonker

Super Anarchist
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3A @ 120V = 360 Watts. Probably within the continuous rating of the inverter. (lots of cheaper inverters have a "Peak rating" much higher than they can withstand for very long)

My last boat inverter was 1000W. It would happily run a 6.7A grinder (800 W) for as long as I cared to operate it.

We had one of these on our last boat. Small enough to stow out of the way but great for sucking out the bilge or fiberglass dust.

1 gal shop vac

NOT good for getting soot out of the diesel heater. The soot was fine enough that it went right through the vacuum's filter and was blown all over the inside of the boat. I am still hearing about it about 8 years later.
 

DDW

Super Anarchist
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The vacuum's load will also peak above 6 amps if the hose is occluded, like when you first put the hose underwater in the bilge.
When the hose is blocked, the power will go down, not up. Less work being done.
A recharble wet dry vacuum (dewalt or similar) would be a lot better plan.
I have a Milwaukee battery powered wet dry. Works better than the DeWalt. Battery life, both running and shelf life are not a problem with it. But it does cost more than $20 or whatever a Buckethead is going for. Does have a real filter, while the Buckethead effectively has no filter.
 
I have a similar Milwaukee cordless vacuum. Very useful for getting the bilge dry. Like all non-marine stuff, the non-stainless things like the hinge pins rust and degrade over the years, but after 5 years its still OK. I don't have any paper filter on this vacuum, which is a big advantage over the typical Shop Vac.

I have all Milwaukee cordless tools, including an angle drill that we use to hoist halyards (instead of electric winches).
 

climenuts

Anarchist
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PNW
A lot of inverters have a soft-start feature where they ramp up to handle the inrush. By turning the device on and then turning the inverter on it does a ramp start.
 

sailak

Super Anarchist
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AK
The type of motors used in a lot of vacuums (universal) have some very high inrush currents.. You could sure try it on 500 and let us know! In my experience 1000 Watts is bare minimum for typical household sort of things with motors and 1500 Watts is usually enough for reliable starts and good service. I run grinders, drills, shop vacs etc from my Xantrex 1500Watt.
 

Grande Mastere Dreade

Snag's spellchecker
3A @ 120V = 360 Watts. Probably within the continuous rating of the inverter. (lots of cheaper inverters have a "Peak rating" much higher than they can withstand for very long)

My last boat inverter was 1000W. It would happily run a 6.7A grinder (800 W) for as long as I cared to operate it.

We had one of these on our last boat. Small enough to stow out of the way but great for sucking out the bilge or fiberglass dust.

1 gal shop vac

NOT good for getting soot out of the diesel heater. The soot was fine enough that it went right through the vacuum's filter and was blown all over the inside of the boat. I am still hearing about it about 8 years later.
or you can try the cheap version
 

Zonker

Super Anarchist
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Canada
Where we were travelling often no chance of replacement, so I preferred to buy something I'd trust i.e. Not HF
 
Beat to use an inverter rated for the surge capacity, which is 720 watts. However, the surge capacity of the 500 watt inverter is probably greater than 6 amps.
I also use a Ryobi One+ (18v) 4 gallon wet dry vac, which I love because of its capacity and portability. And the real filters.
 

sbkenn

New member
4
1
I use one of those cheapo Home Depot Bucket Head vacs to get water and crud out of the bilge.

The vac works really great, but dragging a long extension cord to the boat is a bit of a hassle. (First world problems, I know)

Using a clamp on ammeter, I determined that the vac briefly draws 6amps at start-up and a shade under 3amps while running.

Is it reasonably to think I can run this on a 500w inverter? I could just screw the inverter to the top of the vac!
You really can't tell what the peak current is with a digital meter, clamp or series. It will also depend on which part of the AC cycle is present when the switch contacts close. The instantaneous current is momentary voltage divided by the DC resistance of the motor, less a little for the series inductance. The surge capability of the inverter also takes a bit more to match.
Then there is the FACT that almost every Chinese unit will deliver considerably less than it claims, sometimes as much as 50% less. I know from experience with wind power, I have seen 6kW claimed for a 500W unit ! 3kW is a common claim for that one. Look at the DC terminals, then think "how much current are they likely to handle without getting hot". Something else that I recomment looking at with inverters: If there are a row of screws along the side, they are saving cost by using the case as a heatsink rather than having proper ones inside. I have a Power Jack one that I have been careless with a couple of times. It HAS heatsinks inside, and is well built and modular, so reasonably easy to repair. MosFETs are the usual failure, easy to test and usually easy to source.
 

Great Red Shark

Super Anarchist
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Honolulu
Completely separate from the power considerations, the "Bucket Head" makes for THE MOST unstable vacuum I have ever had to use. Give it one sideways look and it falls right over - top heavy & narrow, it's more annoying than useful.
 
Completely separate from the power considerations, the "Bucket Head" makes for THE MOST unstable vacuum I have ever had to use. Give it one sideways look and it falls right over - top heavy & narrow, it's more annoying than useful.

top heavy & narrow,

Give it one sideways look and it falls right over - top heavy & narrow, it's more annoying than useful.

This is pretty much the plague of the "Shopvac"in general. Do you Know of one that can run over it's own wire without tripping itself over?
 

Quickstep192

Anarchist
836
159
Chesapeake
Completely separate from the power considerations, the "Bucket Head" makes for THE MOST unstable vacuum I have ever had to use. Give it one sideways look and it falls right over - top heavy & narrow, it's more annoying than useful.
I put my bucket head on a three gallon bucket instead of a fiver. Less capacity, but less tippy.
 




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