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Old 04-23-2012, 05:49 PM   #1
Join Date: Apr 2012
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Swapping out inverter?

I recently purchased a new to me 2006 HR Admiral and it has a 140watt inverter. This may be a stupid question but can I simply transfer all wiring over to my larger 1000w inverter I took out of my old motorhome? I want to run my tv and sat. reciever/dvd player off this inverter. Also for some reason the inverter plugs into a 110 wall plug, is that for a fan or is that so when i am hooked upto shore/generator power it has power running through it as my tv is always plugged into it.

Thanks in advance for the help.
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Old 04-24-2012, 09:21 AM   #2
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It's possible that the 140w inverter is a small pure sine inverter, just for running a computer or other digital electric item. As far as switching the 1000w inverter, I'm sure someone with more knowledge than I (just about everyone) will answer that part.
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Old 04-24-2012, 02:14 PM   #3
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Short answer is NO!

A 140 watt inverter (unless you meant 1400) will have very small conductors (wires) supplying it.

Let's just use some off the cuff math.

Ohm's law is volts equals amps tiems resistance

Watts equal amps times volts

and we will just guess and state for demonstration the inverter is not 100% usful of the power, so we will just guess that the overhead of the inverter os 20%, so power in is 20% more than power out, this is only to demonstrate the math.

So a 140 watt inverter will need 168 watts

watts is volts times amps, so divide 168 watts by 12 volts and get 14 amps, so a #12 wire will do for a SHORT distance, forget about voltage drop over the length of the conductor for now.

For the 1000 watt inverter is will need 1200 watts in

1200 watts /12 volts equals 100 amp, thus a #2 or so size wire.

If you had a factory installed correctly installed 1400 watt unit you are fine for wire size, and a direct swap should work unless there are control or display functions.

If you have a 140 watt unit the supply wires will need to be upgraded which would include confirming the supply point is capable of supporting the large load.

You also need to upsize the wire to compensate for losses and peak use, but that is a whole nuther discussion.
Tony & Lori
1989 Country Coach Savannah SE
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Old 04-24-2012, 05:34 PM   #4
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i just tested my tv on and sat on at the same time and it seemed to work off the 140 watt inverter, do i have anything to worry about?

i never dialed my sat in but it was searching for the signal, will it make a difference when it acually finds the sat?

thanks for all the help
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Old 04-24-2012, 08:24 PM   #5
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It will work fine until you exceed the capacity of the wiring.

If the wires area over-fused you may have hot wires.

Verify the wife size that supplies your unit.

Next verify the fuse via removal to confirm it, then make sure the rise matches the ampacity of the wires, if #12 is used then 20 amp fuse.

That will support 240 full watts into the inverter with little risk
Tony & Lori
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Old 04-25-2012, 03:21 AM   #6
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sorry what i meant was do i even need to change the intverter out or will the 140 watt one work for what i need to run, (tube tv/sat receiever)
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Old 04-25-2012, 10:34 AM   #7
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Not sure but you can be.

Every device must have a data plate located on it describing the power needs.

Usually where the power cord is.

So locate this plate on all of your devices and record the loads.

You are looking for numbers with the following units.

W for watts
A for amps
VA for VoltAmps

Since your inverter is rated in WATTS you need to convert all readings to WATTS,
So any reading that is listed as W, WATTS or VA can be used as is.

Any reading that is listed as A or AMPS needs to be multiplied by 120

Now simply add all of these up, if less than 140 you are good to go.
Tony & Lori
1989 Country Coach Savannah SE
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Old 04-25-2012, 01:09 PM   #8
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Depends on how big the tv is. Add up the watts needed for everything that you want to power at the same time. 140 watts is the budget.

You could probably upgrade to 300 watts without stressing the wiring too much, but I would want to see it - or at least know the wire gauge and length) before saying that definitely. It's really only the wiring from inverter to battery that is a concern - it is hard to imagine that the output wiring is not rated for at least 3 amps or 360 watts (18 gauge wire).
Gary Brinck
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
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Old 04-25-2012, 02:42 PM   #9
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Are you sure its only a 140W inverter? That is extremely small for a class A motorhome. I doubt 140W would operate a TV and satellite receiver unless the surge rating on it is much higher.

If you do decide to replace it, the key is sizing the wires for the load, especially on the 12V side.

The Engineering Toolbox has a nice table to show the min wire size.
Amps and Wire Gauge - 12V Circuit
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