Seeking opinions for unusual connection for inverter

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Anonymous - 18 Oct 2005 01:33 GMT

I am getting over 200Ah battery reserve for my RV. I want to explore
temporary connections from this 12v power to the 110v system using a
1200watt inverter so I can run the electric coffe maker and the microwave,
for example.

I am sure I can design an appropriately safe cable from the 110v inverter
output to one of the 110v outlets. The hope is that this introduces 110v to
the appliances until I remove this connection. A question I have is what
happens to the converter that normally tries to charge the battery (I can
see a loop here, 110v now making its round to 12v to charge the battery
which is making the 110v to begin with); is this a problem? Will this work?
Has anyone done this?

Thanks Al

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Matt - 18 Oct 2005 01:44 GMT

I would build a small transfer switch so that when the inverter is on
the power is coming from the inverter only with no chance for feedback
into the converter.

A double pole double throw relay would work. Power the coil from the
inverter output and use the normally open terminals for the power from
the inverter. The normal 110 from the breaker panel goes to the
normally closed terminals on the relay. When the inverter is off the
connection is made to the normal 110 volt source, When the inverter is
on the relay pulls closed and the power to the common terminals comeds
from the inverter. The common terminal is used to feed the desired
outlets. You will need a 110volt relay with contacts rated at least 15
amps. Additonally if you really want to run the coffemaker or microwave
get at least a 1500 watt inverter or even a 2000 watt unit. Remember
that these appliances draw more power on startup than when running and
the inverter needs to be sized accordingly
My two cents for what it's worth. :)

> I am getting over 200Ah battery reserve for my RV. I want to explore
> temporary connections from this 12v power to the 110v system using a
[quoted text clipped - 10 lines]
>
> Thanks Al

Signature

Matt
"Where are we going again, Dear?"

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ninebal310@aol.com - 18 Oct 2005 10:26 GMT

> I am getting over 200Ah battery reserve for my RV. I want to explore
> temporary connections from this 12v power to the 110v system using a
[quoted text clipped - 10 lines]
>
> Thanks Al

Good question! I have thought of doing the same thing. I was thinking
no harm will be done. But then you reminded me of the converter
charging the battery. This would definately pu tmore load on the
inverter. Good point! I will be waiting for others responses.

My only thought at this time would be to plug the appliance in directly
to the inverter. Kind of a hassle, but safe.

Hank <~~~giving this some thought

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Peter Pan - 18 Oct 2005 16:51 GMT

>> I am getting over 200Ah battery reserve for my RV. I want to explore
>> temporary connections from this 12v power to the 110v system using a
[quoted text clipped - 20 lines]
>
> Hank <~~~giving this some thought

I did it so the shore power and gen worked normally, but the inverter, along
with supplying 110 to the inverter, also energized a relay that broke the
connection from the 12v output to the batteries. IE on shore or generator I
had full 110 and 12v for charging the batts, but on inverter I just had 110.
Been using it for a few years that way, works fine.

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Will Sill - 18 Oct 2005 12:46 GMT

I see where "Anonymous" <nowhere@yahoo.com> contributed:

>I am getting over 200Ah battery reserve for my RV. I want to explore
>temporary connections from this 12v power to the 110v system using a
[quoted text clipped - 8 lines]
>which is making the 110v to begin with); is this a problem? Will this work?
>Has anyone done this?

Al, if you have to ask, don't even think about it. Instead, get help
-- or do some research on how to wire in an inverter. It is not
practical to spell out the safe, working methods in a short usenet
post.

Will Sill
The Curmudgeon of Sill Hill

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Jim Redelfs - 18 Oct 2005 13:51 GMT

> if you have to ask, don't even think about it.

No kidding. I was scratching my head... :\

> get help -- or do some research on how to wire in an inverter.

[muttering] transfer switch, transfer switch, (professionally installed)
transfer switch...

> It is not practical to spell out the safe,
> working methods in a short usenet post.

Agreed. They should read your FIRST admonition for good instruction.

I am having a bit of difficulty coming to grips with the realization that, for
many RVers, *CHEAP* is the ONLY way, whether they can afford a better way or
not. (The inverted flower pot heated on the stove burner to stay warm comes
to mind.)

Many of the systems on a modern RV are capable of killing an occupant. Taking
a shortcut with these systems for ANY reason strikes me as strange, at least.
Then there's stupid...

<sigh>
JR

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Mickey - 18 Oct 2005 17:21 GMT

> I am getting over 200Ah battery reserve for my RV. I want to explore
> temporary connections from this 12v power to the 110v system using a
[quoted text clipped - 10 lines]
>
> Thanks Al

Is it possible your converter is wired into the breaker panel and not
on a common breaker as the microwave and kitchen plug? If so all you
would need to do is flip the breaker when operating the inverter.

My converter is hooked up via the breaker panel.

Lot of coment could be made on trying to draw this amount of power
from a battery bank but you didn't ask about that.

Mickey

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Healeyman - 18 Oct 2005 18:43 GMT

I made a short jumper cable with a MALE 110VAC plug on EACH/both end. I
plug one end into my 12VDC powered 2000W inverter and the other end into one
of the wall outlets in the RV.

By doing this, all of the INverter output stays on the high side of the
CONverter and is distrubuted throughout the RV.

I was concerned about issues with the input side of the CONverter, but since
the CONverter input is powered from the shore power plug/cord or generator,
the INverter input and 12VDC house battery charger (diode output) is never
involved.

You and others should examine your wiring diagram/schematic and resolve any
feedback or power distribution issues before trying this. As others have
suggested, you may want/need to install a power relay for primary side
isolation or the isolation of distribution legs.

This jumper philosophy may not work for you, but it works for me.

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Will Sill - 18 Oct 2005 22:17 GMT

I see where "Healeyman" <timoran@verizon.net> contributed:

>I made a short jumper cable with a MALE 110VAC plug on EACH/both end. I
>plug one end into my 12VDC powered 2000W inverter and the other end into one
>of the wall outlets in the RV.

I was trying to remember a more ridiculous and potentially
dangerous/destructive idea, but the only thing that came readily to
mind is setting ones' self on fire to get warm in winter.

Will Sill
The Curmudgeon of Sill Hill

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George E. Cawthon - 19 Oct 2005 01:16 GMT

> I am getting over 200Ah battery reserve for my RV. I want to explore
> temporary connections from this 12v power to the 110v system using a
[quoted text clipped - 10 lines]
>
> Thanks Al

You will need a lot of battery, so I think the
idea is inadvisable. If you proceed, keep the
output of the inverter separate from the 110 ac
circuit. Hook the inverter to the battery with as
short and as big leads as possible. Then run a 12
gauge extension cord from the inverter (nothing
special is needed). Just plug the accessory,
e.g., microwave or coffee maker into the extension
cord.

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