TV \ Inverter

I was curious so I went out to the MH and plugged the TV into the adapter, then the adapter into my 300w PSW inverter. The TV was tuned to a local station with the sound at a normal listening level.

The TV running with the adapter drew 0.14A @ 120v, 16.8W. I couldn't measure the current out of the adapter. The adapter says it is rated at 3A at 12v, 36w.

Running off the inverter and the adapter it drew 2.0A @ 13.2v, 26.4w.

These measurements were done with my clamp-on ammeter.

Doesn't look to me that a 300w inverter is required.

MuddyLane wrote:
I am reviewing the same issue but the gentlemen that are saying their TV's only draw 1.4a @ 12v, I am wondering how are you figuring that out? Are the TV's 12V? If there are 120v the watts would be much more than 17-20watts. I have been currently looking for an inverter myself and my TV draws 1.3 max @ 120V and every place I talk to do not recommend anything small than a 300 watt inverter even though I only need about 160 watts. They say that an inverter should not run more than 80% capacity for any length of time.

I'm one of the "gentlemen" (gee, I don't get called that much. :) ) that has a TV that draws 1.4A at 12V. When I bought the TV I didn't realize that the TV was a 12v TV, but the adapter that plugged into the wall had an output of 12vdc. Sure enough the TV worked fine on the RV 12v system. I measured the current into the TV with my multimeter, and it is 1.4A. I have not measured the AC current when using the TV with the adapter on 120vac. Inverters and adapters are not 100% efficient so I am sure it will draw more than the 17W from the 120v line, and especially the 12v line feeding the inverter, however, inverters are rated by their output so a 50W inverter should run this TV easily. Yes, the TV is a 22" LED TV.

My tv has a power pack that sits on the floor between the wall receptacle and the tv. That power pack has the output rating right on it, and it's miniscule amperage at 12v. The tv can't draw any more than the power pack puts out, so I know that's the Mac mine can draw.

Mine is also an led, which makes a distance in the power consumption compared to even a small tube tv...

I am reviewing the same issue but the gentlemen that are saying their TV's only draw 1.4a @ 12v, I am wondering how are you figuring that out? Are the TV's 12V? If there are 120v the watts would be much more than 17-20watts. I have been currently looking for an inverter myself and my TV draws 1.3 max @ 120V and every place I talk to do not recommend anything small than a 300 watt inverter even though I only need about 160 watts. They say that an inverter should not run more than 80% capacity for any length of time.

The problem is using the 12v outlet to power the inverter. Anyone can check their own to see if they have a problem. First read the voltage across your battery-terminals with a decent multi-meter, Then read the voltage at the 12v outlet with the same meter. Note the difference in voltage. The farther the voltage drops at the outlet, the less power for the converter to convert to 120v ac, and even more loss if the TV has a power block to convert back to around 12v dc.

The other problem here is people pushing "pure sign-wave" versus "modified sign-wave" inverters. There are good and bad MSW inverters along with good and bad PSW inverters. When using the internet check what purchasers say about the equipment they buy.

There are inverters sold over here from across the Pacific being labeled as "pure sign-wave" that are not as labeled. They cause problems same as cheap MSW inverters do. I had a 350 watt MSW (Vector) inverter that ran 3 different TV's fine for 9 years. I now have a N-Power 1000 watt MSW inverter that works just fine too.

One caveat is people with smart-phones, etc., have to be more careful and use an approved 12v, dc, charger, 120v ac, charger on shore-power, or a good brand "pure sign-wave" inverter that claims it works on all 120v ac equipment.

tenbear wrote:
My 22" TV is an LED TV and it draws 1.4A at 12v. That's only 17 watts. I doubt yours draws over 100W but it is possible. I would be suspicious that the 12v at the socket may be low. It would be a good idea to measure it with the TV connected, or connect the TV directly to the battery with short wires as bikendan and MNtundraRet suggested. If that fails I would try a PSW inverter.

I was thinking along the same lines... IIRC, ours is 1.3A @ 12V... Why somebody would need a 100watt inverter to power a 20 watt tv is a mystery to me.

Our particular TV ordinarily uses a power brick to convert 110V AC to 12VDC, and the max output of the brick is rated at 3A IIRC. I installed a regulating isolation transformer to prevent any 12V spikes from the converter or low battery voltage from affecting the output, and it still draws less than 1.5A all together when it's running.

Could be overloaded but I think the issue is low voltage due to the long thin wire from battery to the panel and then to the 12v connector. Or battery is not full charge.

When you are ready to make some changes post what you need in Tech Issues.

The best way for me was to install a 300WATT Inverter as close to the battery bank as you can get and still be inside the trailer. Then run a 120VAC drop extension cord to where you want to use it for your HDTV and other home entertainment as well as camping off the power grid items.

You also may want to run a second 120VAC drop cord to the bedroom night stand area. All of these 120VAC extension cords can be completely out of sight. All that will see is the multiple receptacle 120VAC extension cord head sitting in the back of the cabinet or table.

The Inverter I have is remote controlled and I got the 300WATT PURE SINE WAVE VERSION first and then kept wanting to add a few other nice things to use when camping off the power grid. I finally ended up with a 600WATT PSW AIMS BRAND Inverter ($149-from The Inverter Store)

Has been working fine for us for the past four years now. Of course all INVERTERs are battery hungary and you may want to at least install a second 12VDC Battery or better yet get two 6VDC batteries and connect in series for 12VDC. Successful camping off the power grid works great for us with around 220AHs bank bank capacity.

This is a simple drawing showing how you can install a PSW Inverter in the pass-through storage area as close to the battery bank connections as you can and still be inside out of the wet weather conditions for the Inverter...



I am not a fan of using the 12VDC cigarette type plus for power connections just for the same reason you are now having trouble with. Direct connection to the battery circuit is the best way to go IMO.

I am also not a fan of using MSW type Inverters especially when electronic devices are in the mix. Others get away with the Modified Sine Wave type Inverters but eventually someone will plugin something since the extension cords are laying there in the open and it will go up in BLUE SMOKE. I have lost one electric blanket controller and a couple of 120VAC box fans from using MSW type inverters. Anything using an transformer adapter will get hot on you and TVs and audio items will not work like you want them to with strange noises in the audio or funny looking lines running across the TV screen. To me it just not a good idea however others will tell you it works just fine for them - so there you go... Everything you plug into a PURE SINE WAVE Inverter will work the same as being plugged into a regular shore power connection.

The small extra cost these days getting the PURE SINE WAVE type inverters to me is well worth the difference and peace of mind it will always work.

Just me yaking....

Roy Ken

Without knowing more about the TV I can't tell if it's trying to draw more than 100 watts, but this I do know, When figuring amps, you normally divide watts by volts (at least on the DC side, but more complex on AC)

You would think that means 100/12, but when running through an inverter you divide not by 12, but by 10

This means you are drawing 10 amps

That, is quite likely the max rated current on that 12 volt outlet UNLESS it's the one that's on the wall plate with the antenna connection, then it's less.

You need to get a better inverter (There are some nice 300 watt TRUE SINE WAVE jobs out there) I assume your batteries are on the tong, In this case mount the Inverter in a nearby compartment (If the batteries are inside a compartment mount the inverter in the NEXT compartment) connect with starter cable from your favorite auto store, do not forget a fuse, (300 watts will need at least a 40 amp fuse, but read the owner's manual for the proper size) and run 120 volt wire from the inverter to the TV.

Though some folks get along fine with an MSW inverter,, There is a long list of things that MIGHT not work properly with MSW.

With a True or Pure sine wave, that list is.. Well, non existent.

The only ting on it (is also on the other one) "Items needing more power than the inverter can provide" (Which makes sense)

Which is why I recommend TSW inverters./

You could get a better inverter and that would fix your situation. The smaller 100w inveters don't last for very long.