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Jimbee's avatar
Jimbee
Explorer
Mar 14, 2020

Power inverter question

Hey All,

Silly question regarding power inverter battery consumption. If I'm using my portable 400 watt power inverter to power a 75 watt TV, does the inverter draw the full rated wattage at all times or will it only draw the amount of power it needs to run the TV? I have 300 watts of solar to re-charge the batteries during the day, but it would be nice to watch TV at night for a few hours without worrying about draining the batteries too much.

Thanks!
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Mar 14, 2020
    “but it would be nice to watch TV at night for a few hours without worrying about draining the batteries too much”

    Do you have an adequate battery bank for your power needs? Determine this by an “what I want to use” energy survey. Once the battery power needed is pegged you can compute if 300 solar watts is sufficient for recharging.
  • pianotuna's avatar
    pianotuna
    Nomad III
    Mar 14, 2020
    Divide wattage of device by 10 to know the battery draw in amps.

    75 watts = 7.5 amps.
  • Jimbee's avatar
    Jimbee
    Explorer
    Mar 14, 2020
    Many Thanks,
    I was hoping that the load dictated the power consumption rather than the inverter pulling maximum wattage all the time whether I used it or not!

    Jimbee
  • jkwilson's avatar
    jkwilson
    Explorer III
    Mar 14, 2020
    Input power consumed roughly tracks output power being delivered. Depending on the particular inverter, there is some inefficiency. Up to about 15%, so you’d expect maybe 85W being consumed running a 75W load. There is also a small idle demand, probably about 100mA or a Watt to a Watt and a half.

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