Inverters

[Rohorn]

Hi.....I want to run a 1300 watt wet and dry vac for periods up to 5 minutes off my house batteries. Maybe later a small basic microwave for similar periods. I've got plenty of charging power.
Can I get away with modified sine wave for these two applications, and what size inverter would I need? I want to get away from Honda generators.
Advice appreciated!.....R

<hr width=100% size=1>

 

[sailorman]

try this site
http://www.tlc-direct.co.uk/Products/TLINV1500.html

<hr width=100% size=1>

 

[steve_cronin]

Well. do you have an hour or two? I'll try to be brief but I might omit an (to me) obvious point or two.

Your vac, having run off of a Honda generator seems not to require PURE sine wave input. Therefore the much cheaper "Quasi" or "modified" sine wave output of some mid priced invereters might well do. (Don't be conned by smooth salespersons on this point!)

The other point is power matching.

Although your vac is rated at 1300watts, it might well require much more power to start it's motor. 2000 or 2500 might well be required.

Now on the smart shiney, impressive box of an inverter sold as "1800watts" it might be stated as "start up 2200 watts" or "intermittent 2200watts" This is ONLY valid at some prescribed ambient temperature - often 20C or less. If you're going to use it at 30C then you have bought a 1250watt (1950)inverter which is useless for your purpose. If at 40C (Med in summer) then it is a 900watt (1100) or less machine. I hope that is simple but it gets more complicated:-

Inverter manufacturers knowing that there is no standard in the EC (there is in the USA where the rated output must be sustainable for a specified period -YBSA) vie with each other to publish ever increasing claims as to the possible output of their progeny. The decision is yours!

Anyway that took 20 minutes of my time and I daresay others will contradict - that is the nature of forums like this but you have the benefit of one who is currently looking into such matters for a very seroius purpose.

Steve Cronin

<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[Rohorn]

Hi Steve....Kind of you to reply with such good info.. I note the temperature restraints, the boat is in the Aegean.... Yes, I've been running a normal 1 kw vac off the Honda 1000 genny, but that vac had a variable speed control and I always switched on at the "low" setting, then wound it up when the Honda stabilised. Worked a treat. After sinking half my cat, the Honda is kaput, but it was always a bind to lift it out of the cockpit lazarette and start it, put up with the smell, leave it to cool before stashing it, keep gasoline on board etc etc.
Now, maybe if I dissected the variable speed electric gear off the old vac, and installed it next to the 220v outlet, that would also soften the start-up jolt on an inverter. Or find a stand-alone speed control in an electronics catalogue eg Conrad.
Microwaves presumably wouldn't accept the same treatment, but then the power is only 650 watts.
Thanks again....R


<hr width=100% size=1>

 

[andyball]

Steve...

We're looking for a big inverter or two at present & have seen what you mean about differing ratings.

Has your search revealed any brands to avoid or recommend?

Price & outputwise, for pure sine inverters , two dutch brands seem ok & one at least has had good reviews in uk magazines, but it's a struggle to find much other than manufacturers/dealers blurb about any of them.

& do I trust suppliers? Having just tested overnight a new "marine" dehumidifier with hot gas defrost against a non-hgd B&q cheapy in the same garage (5-7 C last night)......the B & Q has removed twice as much water as the "more powerful" & "works better at lower temperatures" one. Perhaps it wasn't cold enough?. Same situation when tested indoors at 22C.

I may still keep it, since it's very small & only 12" high, so convenient, but tempted to return it today on principle.

<hr width=100% size=1>

 

[William_H]

Steve do you have any idea why a Honda output waveform is so not a sine wave. going only from theory and not paractice it should be quite a good sine wave `being produced by a rotating magnetic field?
Back to the original question it depends on whether the wet and dry vaccuum cleaner has an induction motor ie no brushes runs at 2750 Rpm or if it has universal motor as in an electric drill with brushes running at a higher speed.. The latter type should be fine on square wave and certainly OK on modified square wave while the induction motor is rather fussy about wave form. I wonder if our original poster has considered an alternator belt driven from the main engine to run microwave and other heavy load appliances. Should be good for many Kilowatts.

<hr width=100% size=1>

 

[Rohorn]

Hi....ref fitting a belt driven alternator, with a clutched drive ....nice idea but the cost and effort involved I suspect will be prohibitive. The vac has a universal motor, which of course responds well to speed control, so I think I can fairly cheaply smooth the start-up, and use a 1500 watt inverter.....providing it was a quality product.
Anyone have strong views about, and experience with, a quality, modified sine, 1500 to 2000 watt inverter?
The vac, believe it or not, was made in Belgium, has a stainless steel tank and cost 59 euros! Pennies count in my operation, so a good but inexpensive inverter, if I can find one, is a serious objective.
Never come across a vac with an induction motor.......
Cheers.....R

<hr width=100% size=1>

 

[pvb]

Microwave power ratings...

The quoted power ratings of microwave ovens represent the cooking power - the actual power consumption is much higher. A 650watt microwave would need something like a 1500watt inverter to operate properly.

<hr width=100% size=1>