Powering a 12v TV - Voltage Question.

Discussion in 'General Electronics Chat' started by briandye, May 29, 2016.

  1. briandye

    Thread Starter New Member

    May 29, 2016
    Hi everybody, been a lurker for some time now, new poster. I like to think I have a decent amount of electrical knowledge until I see some of the threads on here! Lol.

    Here's my fiasco:

    I am building (another) "Cooler Stereo" which is just what it sounds like. A 12v stereo system built into a cooler. I've built a few before and am on a monstrous one now, 150qt Cooler on a heavy duty off road wagon axle kit.

    It houses a bunch of electronics, as well as having about 70 useable quarts of space still. I have a large deep cycle 12v battery, I believe it's around 125AH. I also have an on-board charger, which charges at up to 10a. (Genius brand)

    I went a huge step further with this build and incorporated a 19" LED TV in the underside of the lid in this one. It's an "Element" brand, very common set used in RV's, Boats and cars because of the ability to run on 12v. I have read thread after thread of people just snipping the cord at the power brick (120v AC input to brick, brick outputs 12v DC) and splicing it to a cigarette lighter plug or hardwiring it.

    I hard wired mine with a fuse and switch, but my question is, how sensitive is it to voltage spikes? It works phenomenally at the resting 12.6ish volts my battery sits at.

    I watched an hour long episode of a Netflix show, playing through the headunit in the cooler, and had very little battery drain. I was impressed, but I digress.

    When I charge the cooler, the charger sometimes reaches 14v (14.4ish seems to be the highest I have saw, but then again, I haven't really ever drained it much. Just been "top offs"). I have always kept the TV off (the switch cuts power to the TV, I'm not talking just having the TV off).

    My question is, would that 14v hurt the TV? Does it have some kind of voltage step down unit inside or anything? I don't want to risk it and "just try it" like some other forums have said. (I've seen a few threads similar to what I'm asking, but never once a definite answer) I picked up the last unit Meijer had, and they weren't getting any more of these in stock. (The new model did-away with 12v, and has a straight AC cord permanently attached. Don't ask me how I know lol)

    Thanks guys for any input! Appreciated in advance!
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    More than likely totally fine... But only the manufacturer would really know as there is no "standard" on how much over voltage something may allow..
  3. briandye

    Thread Starter New Member

    May 29, 2016
    I'm so tempted to just try it, since I can order a new one online for about $80 but I would be so pissed.

    If it did "fry" it, is there a common replaceable part I could just replace/solder/etc? Or do you think it would fry the whole board? I see people repairing broken LCD/LED TVs, I'm sure some of them had a power issue. I dunno, we'll see. I'll definitely post back if I do, and what happened.
  4. ian field

    Distinguished Member

    Oct 27, 2012
    It would seem reasonable to assume that a 12V TV would be rated for the voltage range you'd expect on a car battery.

    Technically the maximum would be around 14.4 - 15V - but I'd expect it to survive 16V.

    AFAICR: the heater voltage in the old B&W portable TVs was 11.5V - if you know where to look; a data sheet should tell how good my memory is.

    I'd assume most, if not all colour portable TVs have SMPSU, so makers specifications should give a reasonably good guide to the range that should be aimed for.
  5. AlbertHall

    Well-Known Member

    Jun 4, 2014
    I too would expect it to survive unharmed. Is there a rating plate on the TV that might give you a clue.
  6. Lestraveled

    Well-Known Member

    May 19, 2014
    All the other RVers would have subjected the TV to the same voltage changes (higher than 14 volts) that you will. If you got good reviews about it operating on 12V RV battery systems then I think you are good to go.
  7. NCSailor

    New Member

    Jun 15, 2013
    I think most of the responders either misunderstood the OP's TV or I did.
    My understanding of the TV is that it is not a 12V TV but a 120VAC TV that uses a PSU to convert the 120VAC to 12VDC. If this is a good PSU, it will output very close to 12V under all normal conditions and is thus not comparable to the 12V available from an unregulated RV or automotive 12V system.
    I think Lestraveled comment is on point, however, it assumes that people operate the TV while the RV is under power.
    I would first check the output from the original PSU. It may in fact be well above 12V and then all should be fine. If it is closely regulated, then I think I would add a DC - 12VDC SMPS in the supply circuit. This would be simple and cheap insurance.
    My experience (in the marine industry) is that unless a device was designed to be powered by a 12V cigarette outlet or similar, they do not live long on the 10.8 to 14.8 voltages found in automotive and marine systems.