LCD TV Powered by DC?

[svcattales]

We have a 15" LCD TV on the boat. When I looked at the square transformer in the AC power cord, it converts 120V AC to 12 V DC. Any problems in running this directly on 12V DC? This will avoid turning on inverter and consume less battery power.

[Alan Wheeler]

No problem with running it on 12V DC. But the problem you have to watch is that the DC system on the boat is NOT 12V. It will drop bellow 12V when batteries are down and then most worryingly, it will climb to 14V or more when under charge. So you have to ensure the LCD can handle the voltage range. Low voltage won't be the issue, apart from poor performance, but careful of the higher voltage. However, in saying all that, I would also suspect it will be fine.
You can also buy a DC/DC regulator that will insure that the higher voltage input will always remain at a constant 12V output.

[Rick]

Like Wheels says, "12V" in a boat is not what is called "nominal" and certainly not specific as might be the LCD input requirement. Always assume that boat and RV "12V" is anywhere between 10 and 16V for the purposes of applying sources and loads.

Although the voltage may exceed 16V under abnormal conditions protection devices properly applied and installed can ensure safe operation of most devices. Although the battery voltage may drop below 10 V to 8 or so, usually one should specify a dc/dc converter to function with the inputs between 10 and 16V without damage or loss of regulation.

I have been running my 22" Sharp LCD on battery power since I got it about 2 years ago, with no problems. It does not seem to mind the power variences much. I do not have it on when the engine is running and charging, so I do not worry much about exceding 12.5 volts.

[svcattales]

Thanks for the inputs. Kai Nui, its good to know that someone has made it work. We also have a Sharp TV. I think we are going to try to regulate voltage since the TV will double as display for electronic charts and we sometimes run the engine when underway..ha..ha. Called Radio Shack and they have a DC to DC power supply that might solve the problem. I have to check out the polarity first before I buy it. They said it is only 8 bucks. May see if they have one that will run the lap top computer also.

Just a warning with the Sharps, if you have not tried to use it as a monitor yet, we had that in mind, and found out that ours would not work as a monitor. We figured it was just due to not having a USB, so we bought the converter, and found that 640x480 was the only resolution we could get on the 22" screen, and it was so distorted, and blurry that it was unusable.
And I did not say I did not use the engine underway, but for those of us who suffer from mal de mer, watching TV while under way is not high on the priority list. Stil the DC-DC converter, if you get one that is 12-12 will work fine, and is a good idea.
Good luck with your project.

[svcattales]

Kai Nui, thanks for the advice. I will do some testing with the laptop before doing any installations. Our plan is to put the TV on a mounting arm that swings into the companionway door area for navigation and swings into the salon for TV. Hope it works.

Another thing to consider, is the more functions one component performs, the more funtions you loose if one component fails.
I am for simplicity, but often that means more pieces doing simpler things. Flat LCD computer monitors have gotten cheap enough, to dedicate for such things, and powered with a laptop, you always have a back-up. If you are bound and determined to consolidate the TV into this mix, they make a board for the computer that will allow it to receive TV. Sounds more complicated, but this setup will allow a back-up for each system, 2 TVs and 2 monitors. (the built in on the laptop).

[svcattales]

Kai Nui, I have the same philosophy about most things. I avoided the tempatation to buy a chartplotter/radar combo because I didn't want one failure to kill two important instruments. On the TV, the mounting location works out to be the best spot for two "lounging lizards" to see the screen while laying across the settees. If the TV quits, we can still use the laptop for navigation and read more books instead of watching TV...and save some precious amps.

[delmarrey]

I also have a Share LCD TV. When I first bought it I e-mailed Sharp asking if I could bypass the 110VAC transformer and run it on 12VDC or if they had an adapter. And their reply was just basicly "NO". I didn't really believe them except the problem I had was which wire is ground. I assume it's the outer ring of the adapter plug but I wasn't willing to find out the hard way.

Anyway, I just run mine through the inverter for hours and I don't even notice a voltage drop out of two group 27 batteries. I also bought one of those portable DVD players that plug into the cig lighters and use the Sharp as the monitor. Trying to keep a channel an a pitching and yawing boat is frustrating. So I rent DVD's when on the hook................................._/)

Greg, as a fellow TV addict, I find it amazing how much consideration I give the TV on the boat And yes, a comfortable position to lounge while watching is very important.
I am not surprised sharp advises against the conversion. As for determining wich pin is positive, I put a multimeter to ground, and tested the out put end of their cord to determine wich one was positive. I purchase a unversal power cord from the local office supply, that allows me to use the same cord for 110/12v, on multiple appliances. I needed to replace the power cord on my laptop, so I chose one that would work for everything.
I will agree that Delmaray is correct about the AC power draw. Even using the set on AC, you will barely notice a draw. Unfortunately, if you do not have a very efficient inverter, the darw will be far greater adding in the idle draw, and the efficiency factor. Off shore, where power is a far more valuable commodity, 1 or 2 amp/hrs is an important issue (maybe 20%-40% or your referigeration budget). And for those who say just read and save the power all together, off watch, sometimes there is nothing better than some mindless entertainment like a DVD. Sometimes a book or card game is just more than I am up to.