Author Topic: inverter  (Read 3852 times)

Offline tony

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inverter
« on: February 25, 2011, 10:12:23 AM »
i need to put the ? a little diff with more details  i have a 1980 mci buse i have wired it for 120 volt and i have an 8k des generator i am looking at an inverter on ebat 4 or 5 k  24 volt to 120 volt my fridge will run on gas or electric i have a roof air that is electric 120 volt 20 amp would it be better to just use the gen when i am going down the road or an inverter and do you think the ones on ebay would work they cost about 500 thanks tony

Offline Sean

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Re: inverter
« Reply #1 on: February 25, 2011, 10:47:02 AM »
You probably don't want to run an absorption fridge on battery power.  If you are concerned about using LP while driving, then running the electric element from an inverter is a good option, but make certain you switch to LP when you stop.

As for the A/C, hard to answer without knowing more about what inverter you are looking at.  You need a true sine wave model to run induction motors, and I would guess that the $500 model from eBay is MSW instead.

Whether you want to run your generator while driving vs. using an inverter off the alternator is a personal choice.  If you already have the inverter, because you need it for boondocking or whatever, then it's an easier decision, because you've already got the hardware.  It always takes less fuel to power things from the main engine alternator than from a separate generator.

-Sean
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Offline Oonrahnjay

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Re: inverter
« Reply #2 on: February 25, 2011, 11:40:21 AM »
(snip)  I would guess that the $500 model from eBay is MSW instead.  (snip)

Yeah, in comparison to everything I've seen, this looks like a "something for nothing" situation.  I know that people sell good things for cheap prices on EBay but this is "too good".  You *may* get an inverter that will take alternator output and run an A/C and other things, but it just doesn't seem likely.  If it's a "4K inverter" that is actually 4K peak/2K continuous (often sold on EBay), then it might not run a 120v/20A air con at all; if it does, there won't be any extra power to run other things (microwave, fridge, etc.)
And it just doesn't make much sense to use a non-code-approved inverter in a vehicle; even if it doesn't burn up (and take your bus with it), you'll get lots of heat from insurance companies, valuation co's, when trying to sell, etc.

Find a quality inverter that's properly sized to your needs with known feeds for the amount of watts your alternator can supply compared to how many watts you need to supply -- and is approved for vehicle use -- and see what that's like in comparison to this.  I'm guessing that this EBay unit will fall short.
Bruce H; Wallace (near Wilmington) NC
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Offline happycamperbrat

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Re: inverter
« Reply #3 on: February 25, 2011, 11:56:24 AM »
I have read that with the modified inverters they can handle small loads pretty well but a pure sine wave inverter needs to be nearly maxed and smaller loads will burn them up quicker. I dont know how true this is and hopefully people with knowledge/experience will comment on that, but I "believe" it would be something to consider in buying one of the cheaper off brands........
The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post

Offline Sean

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Re: inverter
« Reply #4 on: February 25, 2011, 12:01:44 PM »
I have read that with the modified inverters they can handle small loads pretty well but a pure sine wave inverter needs to be nearly maxed and smaller loads will burn them up quicker.
This is complete balderdash and I would guess that whoever provided you that information has something to sell.

In fact, almost all inverters are more efficient at lighter loads.

FWIW, I have a 4kW inverter and it mostly runs the internet and the clocks on the microwave and coffee pots all day, less than 150 watts.  The only time it ever sees 4kW is when we are running down the road with two air conditioners running.

-Sean
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Offline thomasinnv

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Re: inverter
« Reply #5 on: February 25, 2011, 03:53:11 PM »
HCB, Psw are generally slightly less efficient than msw under similar power usage levels... and large inverters (say for example 2000w or higher) are often less efficient than smaller inverters (say 500w or so) when they are under no load, or standby power consumption.
Some are called, some are sent, some just got up and went.

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Offline happycamperbrat

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Re: inverter
« Reply #6 on: February 25, 2011, 04:13:33 PM »
Everyday I am thankful for the knowledge and sharing in this group! Thanks guys!
The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post

Offline Joe Camper

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Re: inverter
« Reply #7 on: February 25, 2011, 05:24:41 PM »
Something else I needed to do on our bus.

I moved a cruise air, the front one, over to an inverter a 2500 w 24 v Heart. I have to manage my loads while doing it but i felt it was a compromise I was willing to make for the added comfort. if Deb wants the micro or a curling iron I have to momentarily turn it off for those larger intermitten loads. All the other constant loads are small and combined do not overload it.

So that all works great.

The problem arises when you go to shore or gen and your camping. Because all the a/c current still flows thru the inverter when it is in charging mode that makes everything too inconvenient to be managing around when camping specifically all the big draw stuff like the kitchen appliances we do not do going down the road.

I ran the power source with a switch thru a relay and solenoid. So when we are NOT underway I can get that cruise air off that inverter circut and back where it belongs so we can use most of the appliances that are on that inverter circut at will and as designed.

Does that make sense I hope?
« Last Edit: February 25, 2011, 05:28:14 PM by Joe Camper »
Signing off from Cook County Ill. where the dead vote, frequently.

Offline Sean

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Re: inverter
« Reply #8 on: February 26, 2011, 12:26:55 PM »
... Psw are generally slightly less efficient than msw under similar power usage levels...
That's only true for 100% resistive loads.  If there is any inductance at all, MSW is always less efficient than SW.  And, as I have written here many times, induction motors should never be run on MSW; if they don't burn up outright, they (and thus the inverter) will use 10%-20% more power than on SW.  That would include air conditioners as well as household refrigerators.

-Sean
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Offline Lin

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Re: inverter
« Reply #9 on: February 26, 2011, 01:32:31 PM »
We have a Trace MSW inverter.  It is very useful, but has its limitations. Of course, we do not use it for an motors so airing up with the aux compressor requires the generator.  I will use it for the microwave sometimes, but the microwave sounds to me like it's laboring, so I tend to turn on the generator if it is to run more than a minute or so.
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Offline Cary and Don

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Re: inverter
« Reply #10 on: February 26, 2011, 01:33:24 PM »
Kind of a related question.  If you are running the air conditioner through the inverter off the engine generator,  do you need any additional regulation for the generator?  We attached the generator feed through an isolator to the house batteries  and a magnetic switch.  This way we can either hook the house batteries into the bus feed or leave it off.  Is there anything else that would be better?

Don and Cary
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Neoplan AN340
1973 05 Eagle
Neoplan AN340

Offline dougyes

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Re: inverter
« Reply #11 on: February 26, 2011, 07:02:11 PM »
Tony, If you add some periods to the ends of sentences and capitalize the first word it will be a lot easier for us to read your posts.

Offline Joe Camper

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Re: inverter
« Reply #12 on: February 27, 2011, 06:31:33 AM »
Don that discription matches ours.

1 large alternator for the chassis and the house also works great for us.

Signing off from Cook County Ill. where the dead vote, frequently.

Offline chart1

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Re: inverter
« Reply #13 on: March 02, 2011, 01:04:29 PM »
I have been looking at some inverters. My ? is do all of them have 3 prong plugs for the 110 side or do they have some for direct wire with electrical lugs like what is on the 12v side.
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Offline Sean

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Re: inverter
« Reply #14 on: March 02, 2011, 03:52:17 PM »
I have been looking at some inverters. My ? is do all of them have 3 prong plugs for the 110 side or do they have some for direct wire with electrical lugs like what is on the 12v side.
Whole-RV inverters are hard-wired on the AC side.  The ones with direct receptacles can only be installed directly at the point of use (for example, to run a television set).

-Sean
http://OurOdyssey.BlogSpot.com
Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com