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Author Topic: Ok, weird question I know but...  (Read 778 times)

Oilersman

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Ok, weird question I know but...
« on: May 11, 2020, 09:54:12 PM »
So, my scenario, large RV with a fairly large deep cycle battery bank. What I want to do is this. Kids want to watch tv at night and I don't want the genset running. The battery bank runs DC loads only of course so lights and controls. Now for the weird part... Hookup my inverter on my battery bank and plug the shore power cord to this inverter for tv power. This looks like an odd cycle that may or may not work and I don't know if this would damage anything? Definitely would have inefficiencies and losses but it's only for a few hours and I'll recharge at some point from the genset  the next day. Any ideas on this? Thx guys. 😊

Isaac-1

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Re: Ok, weird question I know but...
« Reply #1 on: May 11, 2020, 10:06:00 PM »
There are better ways to do this, and if you did it your way you would want to always make sure to turn off the converter so it is not trying to charge the batteries that your inverter is drawing power from, also you would want to make sure the refrigerator did not auto-switch to shore power.  A better way would be to only power the one circuit that powers the tv with the inverter, either through an auto transfer switch or manually plugging a cord in.

p.s. modern tv's don't draw much power, usually under 25-30 watts for most models, there are also models that can be powered by DC directly from the batteries, so potentially avoiding the need for an inverter.
« Last Edit: May 11, 2020, 10:07:32 PM by Isaac-1 »
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MartyB

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Re: Ok, weird question I know but...
« Reply #2 on: May 12, 2020, 06:59:02 AM »
That's exactly how I do it.  No, it's not the best way, but it is the easiest, and it works.
Marty and June
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Gary RV_Wizard

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Re: Ok, weird question I know but...
« Reply #3 on: May 12, 2020, 09:03:43 AM »
Plugging the shore cord direct to an inverter has a major drawback: the RV's own converter charger gets powered and tries to pump amps back into the same battery the inverter is drawing from. That's a power loop that will usually run the batteries down very quickly. You need to do something to stop the onboard charger from running, e.g. turn off its circuit breaker, unplug it from its outlet, or disconnect it from the battery bank.
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Great Horned Owl

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Re: Ok, weird question I know but...
« Reply #4 on: May 12, 2020, 09:42:27 AM »
I operated for several years by plugging my shore power cord into my inverter outlet. It worked fine until the time that I forgot to turn off the breaker to the converter first. That depleted my batteries rather quickly. After that, I inserted a normally closed relay into the 120 volt feed to the converter, and connected the coil to the inverter output. that way, the converter and the inverter could never both be on at the same time.

For what you need to do, there are much simpler solutions. You can just get a small inverter (about 200 W) and plug just the TV into it. Even simpler, would be to get a 12 volt TV. There several nice ones available. Several even have a built in DVD player. Look at this one https://www.amazon.com/TVD1805-24-24-Inch-Features-Technology-Function/dp/B074WLZ1GJ/ref=sr_1_3?dchild=1&keywords=12+volt+tv+dvd+combo+axess&qid=1589295785&sr=8-3.

Joel
« Last Edit: May 12, 2020, 10:05:13 AM by Great Horned Owl »
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John From Detroit

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Re: Ok, weird question I know but...
« Reply #5 on: May 12, 2020, 05:51:51 PM »
The biggest issue is the converter that normally charges the battery

Battery feeds inverter feeds shore cord feeds converter feeds battery  Both converter and inverter are 80-90 percent efficient so this is a leaky tank.

Better to run extension cord from slaller (say 300-600 watt) inverter to TV direct not power rest of house.
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Domo

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Re: Ok, weird question I know but...
« Reply #6 on: May 13, 2020, 11:32:00 AM »
Hook the inverter to the batteries.

Run an extension cord from the inverter to the TV.

No conflict with charger, etc.

Done.

Depending on the TV load, you may be able to get a small inverter that simply plugs into a cigarette lighter in the rig.

We used to have a TV that used a 12 Volt wall-wart (120 VAC stepped down to 12 VDC center positive) - I threw away the wall wart and simply installed a cigarette lighter socket behind the TV and plugged it in with NO 120 VAC required. That was a 20" Element TV from Walmart for around $100.
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Ex-Calif

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  • Dan from Dayton...
Re: Ok, weird question I know but...
« Reply #7 on: May 18, 2020, 01:50:02 PM »
"Depending on the TV load, you may be able to get a small inverter that simply plugs into a cigarette lighter in the rig."

That's what we do when Jeep camping but we are only charging phones and iPads... Gotta be careful in the Jeep if we flatten the battery and get stuck on a mountain somewhere - LOL

Check the tv label for current draw - If it's a smaller/newer tv it's probably well within the capabilities of one of these.

There are a lot of other solutions - Most of the youngins don't even watch TV any more (I am a convert too) - If you have Wifi you can stream to an iPad. If you don't have wifi (or are gonna be out of touch) there is a ton of content that is downloadable to iPad - I load up on international business trips in advance and watch iPad on planes and foreign hotels where there may be nothing watchable.

You can also watch directly on a laptop with a separate laptop monitor which is also a very low current draw solution.
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Utclmjmpr

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Re: Ok, weird question I know but...
« Reply #8 on: May 18, 2020, 02:59:19 PM »

 You say it's a large RV with a large battery bank,, most RVs of that description have an on board inverter already hard wired in,,,whats the problem..???>>>Dan
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The difference between intelligence & stupidity is: intelligence has it's limits
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Ex-Calif

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Re: Ok, weird question I know but...
« Reply #9 on: May 18, 2020, 03:21:29 PM »
@Utclmjmpr

If that >>>>Dan reply was for me, I guess I thought the OP wanted to know about running 110V plugs in the RV off battery power - I was offering some DC solutions as well as a very simple AC solution for low amp loads...

Sorry if I misinterpreted OP's question...

BTW - I see you have a Jeep Liberty - Mine's a 2012 - Love it!
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Various classic MGBs
Ex-liveaboard boater - Class A newbie in sponge mode

Utclmjmpr

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Re: Ok, weird question I know but...
« Reply #10 on: May 18, 2020, 06:06:27 PM »
 EX,, 2012 was the last year for the Liberty,, I had the first year,, 2002 and wanted the last year when Jeep dis-continued the line..>>>Dan is for me... Are you a Daniel, or a Danny?
« Last Edit: May 18, 2020, 07:20:14 PM by Utclmjmpr »
Vary rare American Tradition 38TT/330 turbo Cummins
Last year Jeep liberty 4 down
72 VW Baja 4 down
Cedar City, Utah
USAF vet. 59-63
FMCA F312919
The difference between intelligence & stupidity is: intelligence has it's limits
      Albert Einstein.