How to power a 32" LCD TV.

mwilsonnm
mwilsonnm Solar Expert Posts: 26 ✭
in Off Grid Solar & Battery Systems #1
I have a 12volt system with a 675 ah battery bank. I attempted to power a 32" LCD TV that consumes 92 watts with a MSW inverter rated at 200 watts. All I got was a brief flash of light initially and then nothing. The set works fine on AC. Any ideas? Thanks Mark
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: How to power a 32" LCD TV.

    Modified (square/sine) wave inverters (MSW) can play havoc with power supplies. Some will overheat/fail or not work correctly (MSW peak voltages are less than Sine Wave peak voltages).

    There are so many types of power supplies out there--It is difficult to say if yours should work well with MSW or requires a TSW (true sine wave) inverter to work correctly.

    In any case, if you are looking to go off grid/long term emergency power--You probably would be better off to look at newer LED based TVs... They appear to use 1/10th or less power than your present TV.

    Off grid / emergency power is all about conservation... It is almost always cheaper to conserve vs generate power.

    A very rough rule of thumb, grid power costs around $0.10 to $0.30 per kWH... Off grid power around $1.00-$2.00+ per kWH.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #3
    Re: How to power a 32" LCD TV.

    Hi Mark, welcome to the forum!
    Couple of things quickly come to mind. First is that the startup surge (charging up capacitors etc) of the TV is greater than what the inverter is capable of supplying long enough to allow the TV to get stabilized in normal operation. Second, many of these smaller MSW inverters have exaggerated power output claims, and it may just not be capable of running the TV. And finally, the 3'rd of the two things I had thought of, is the possibility of the 12 volt supply voltage as it appears right at the inverter terminals is dropping under load, to the point where the inverter kicks off under low voltage. That could be caused by batteries in poor or undercharged condition, or poor connections (gator clips instead of good solid bolted tight connections, or wire too small and too long for the job. The TV, drawing 95 watts, could easily be sucking 8 or 10 amps out of the battery, so everything there needs to be A-1.
    If the battery and connections are OK, then I'd fully question the performance of the inverter.
    And of course, depending on the internal power supply of the TV, it might not work right at the best of times on MSW, and could in fact emit smoke. Expensive smoke. And of that, there's no way to tell in advance, it's the luck of the draw. Most TV's are OK with MSW, but that doesn't mean yours will.
    Hope this helps.
    Wayne
    PS: As usual I'm slow composing my response, so didn't see "BB's" till after I posted mine :D
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  • mwilsonnm
    mwilsonnm Solar Expert Posts: 26 ✭
    #4
    Re: How to power a 32" LCD TV.

    Thanks for the info...both of you. I suspected the inverter was proably the issue as my battery bank was fully charged and the wire run to the TV was apprx. 6 feet of #10 awg. I have since discovered the power saving feature of LED TV's, as Bill mentioned and the LCD set has found a place in my permanent home. Looks like it's time to find an LED set for my cabin. Thanks.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #5
    Re: How to power a 32" LCD TV.

    Also, as Wayne said--Check the DC terminals at the battery bank and the AC inverter... Many folks have used cable clamps to connect to the battery bank--And those connections are not, usually, near good enough to even run a "smallish" power inverter.

    Hard bolted up connections with some anti corrosive grease and heavy copper wire between the battery and inverter's DC input--All needed to reduce the chance of the DC input voltage failing below the minimum input voltage for the inverter (especially when starting AC loads).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #6
    Re: How to power a 32" LCD TV.

    Good example of the lower power consumption of the LED TVs, I just bought a 60" model which draws nearly the same as your 32" @ 99 watts.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • DavidOH
    DavidOH Solar Expert Posts: 112 ✭✭✭
    #7
    Re: How to power a 32" LCD TV.

    Check and see how soon it is worth getting a new TV. The LED TV's use much less electricity. Some that size use less than 30 watts. While you are checking on them ( Look in stores at the BACK of the TV ) look for the power supply. Some of the new ones use EXTERNAL power supplies. 12 Volts! Vizeo and Samsung are just a couple. If you use a 12 Volt DC powered set you can eliminate the inverter trouble and it's power losses altogether!
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  • Kevink_2017
    Kevink_2017 Registered Users Posts: 1 ✭
    #8
    Would a 115ah battery suffice to power the TV?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #9
    Need to know the voltage of the battery bank too... Say it is 12 volts, the available power would be:
    • 115 AH * 12 volts = 1,380 Watt*Hours of storage
    Say you have a TV that takes 30 Watts 12 VDC. And you discharge the battery to 50% maximum (recommended for longer battery life):
    • 1,380 WH  * 0.50 max discharge = 690 Watt*Hours of "useful" energy
    • 690 WH / 30 Watt load = 23 Hours of TV time (lots of guesses here) to 50% discharge
    Say you have a smallish AC inverter and use 120 VAC @ 30 Watts for the TV--You have some lost energy in the AC inverter (85% efficiency is a good number for planning):
    • 690 WH storage * 0.85 AC inverter eff * 1/30 Watt AC load = 19.55 hours of run time
    It is always a good idea to use some sort of energy meter to measure you loads--For example:

    https://www.solar-electric.com/kiacpomome.html (Kill-a-Watt AC meter)
    http://www.rc-electronics-usa.com/electrical-test-equipment.html (DC Watt/AH meter)
    http://www.sears.com/craftsman-digital-clamp-on-ammeter/p-03482369000P (AC/DC Current Clamp DMM)

    If you want more discussion, please feel free to start your own thread--That way we can discuss your questions without earlier discussions confusing your issues.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #10
    I use a 32" samgung led with thumb drive port at 18/20 watts.
    I can down load 1000s of movies on to a few thumb drives, and plug them in with out useing extra power.
    I use a pro sine 300 watt inverter
    The tv has the best picture of all the small tvs .
    I think a small samalex inverter 150/200watt will start the Samsung 32"tv.
    A DVD or cable box uses 35/120 watts? So check it out with a watt meter
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #11
    I used a 12v g 31 for a few months and I could use the tv radio and some lights and water pump for 2 days .
    I would take the battery home tocharge.
    2 golf cart battery's would be better
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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  • PNjunction
    PNjunction Solar Expert Posts: 762 ✭✭✭
    #12
    A general comment to saving even more power while watching ....

    While "power savings" features are good if they are available, you may be able to save even MORE power by overriding it and adjusting things yourself.  Think of it as a big laptop. :)

    In this case, turning down the *BACKLIGHTING* to as low as you can stand it will reduce current consumption far more than reducing brightness.  I always get the two confused at first, but pretty soon you'll remember backlighting reduction first, THEN adjust brightness.

    Toggling these two, especially if you darken the viewing area first, can really cut down on the current draw.
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