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DC - AC Power inverter

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Hilda Winkler

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Jul 21, 2021, 6:15:45 PM7/21/21
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hi group, why won't a 1.0 hp wet/dry vacuum cleaner model 2010. 120v 60hz 5.5a. Work on a 4000w 110v DC - AC Power inverter ..???

Rheilly Phoull

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Jul 21, 2021, 7:57:41 PM7/21/21
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On 22/07/2021 6:15 am, Hilda Winkler wrote:
> hi group, why won't a 1.0 hp wet/dry vacuum cleaner model 2010. 120v 60hz 5.5a. Work on a 4000w 110v DC - AC Power inverter ..???
>
What size battery ?

Hilda Winkler

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Jul 21, 2021, 9:38:14 PM7/21/21
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12v hooked up directly to the terminals..

Rheilly Phoull

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Jul 21, 2021, 10:05:25 PM7/21/21
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As in ampere hours, can you measure the battery voltage when the load is
connected ?

Rheilly Phoull

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Jul 21, 2021, 10:09:56 PM7/21/21
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Bearing in mind that at those levels, the battery will need to supply
several hundred amps for the motor to run.

Hilda Winkler

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Jul 22, 2021, 6:35:33 AM7/22/21
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Tested 12.4v before the load, 12.3 with the load,.

Phil Allison

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Jul 22, 2021, 6:39:21 AM7/22/21
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hildawi...@gmail.com wrote:
----------------------------------------------------
<
>> .... the battery will need to supply
> > several hundred amps for the motor to run.
>
> Tested 12.4v before the load, 12.3 with the load,.

** Wot load ?

You said the vac did not run.



..... Phil

Rheilly Phoull

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Jul 22, 2021, 10:30:34 AM7/22/21
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Yeah, like Phil said ??

Peter W.

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Jul 22, 2021, 11:39:19 AM7/22/21
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Mpffff.

One Horsepower = 746 watts. For now, let's ignore the starting surge.
746/110 = 6.78 Amps. That is the *AC* load for the motor when running.
746/12 = 62.2 amps from the battery to make that load.

Now, consider the starting surge (typically six (6) times the running current).
That battery would need to put out +/-373 amps for the start.

This also ignores inverter losses (typically between 5 & 15% - 5% for a grid-tie type, 15% for most others).

The inverter may be rated at 4,000 watts. There are very, very few conventional automotive-type lead-acid batteries that could sustain it.

Peter Wieck
Melrose Park, PA

Ralph Mowery

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Jul 22, 2021, 12:44:53 PM7/22/21
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In article <d6d719a3-3fcb-46cf...@googlegroups.com>,
peterw...@gmail.com says...
I have often wondered why there are inverters out that convert 12 volts
to much over 1000 watts. Even that is high, but it may take that to
start the small motors or the input rush of other electronics.

As you pointed out it takes a very large battery to provide that much
power for very long. If you are going to run an engine to keep
thebattery charged, you might as well use a 120/240 volt generator in
the first place.

Rheilly Phoull

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Jul 22, 2021, 9:30:25 PM7/22/21
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So Hilda there you have it, from multiple sources !!

Phil Allison

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Jul 22, 2021, 10:57:54 PM7/22/21
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Ralph Mowery wrote:
=================
>
> >
> I have often wondered why there are inverters out that convert 12 volts
> to much over 1000 watts. Even that is high, but it may take that to
> start the small motors or the input rush of other electronics.
>

** These supplies use " modified sine wave" aka variable pulse width rectangular waves.

The peak voltages are the same as the usual AC supply.
A lot of overload current could be avoided by having a "soft start" system.

The unit would need a "start" button that brings up the duty cycle of the output wave from zero over a few seconds.


..... Phil
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