Inverter AC Voltage

Discussion in 'General Electronics Chat' started by alkit, Feb 26, 2015.

  1. alkit

    Thread Starter New Member

    Feb 8, 2015
    6
    0
    Hi,

    Just a quicky:

    Busy testing some 500W MSW inverters.
    I find that some of them start losing AC voltage as the battery starts draining.
    They start at 220V AC output but go down to around 180-190V.

    Is it safe to power my electronics at that low voltage?
    Is it normal to go down to that range or does it indicate a fault with the inverter?

    Thanks in advance!
     
  2. Reloadron

    Active Member

    Jan 15, 2015
    963
    232
    You don't mention the battery voltage? Some use 12 volts and some use 24 volts? You also don't mention the load you are applying? If testing an inverter you should be looking at the output voltage under various loads. However, a 500 watt inverter under a full load on a 12 volt battery for example would be 500 watts / 12 volts = 41.7 amps. That does not begin to consider the inefficiency of the inverter itself and energy lost as heat. You would need to measure the current draw at the battery and the current at the load for starters.

    As to your electronics? I have no idea. You need to read the nameplate data on the actual electronics you have. My home computer for example is 120 VAC 60 Hz. between 90 and 240 VAC. So if I go below 90 volts then I will have problems. My guess is your inverter is either overloaded or your battery is not able to support the load.

    Ron
     
  3. alkit

    Thread Starter New Member

    Feb 8, 2015
    6
    0
    Thanks for the reply:
    1) Battery is a 102Ah deep cycle 12V battery
    2) Load is 140W
    3) I have no idea of the electronics, as they will be changing all the time. I just wanted to check if it is normal for the voltage to go down so far and if there are any electronics that would be affected by the lower voltage? I know for example, if I connect a lightbulb, when it starts drawing less Volts, the light starts to go dimmer. I'm just wondering how that would affect a TV, computer, Set top box etc.

    Thanks
     
  4. Reloadron

    Active Member

    Jan 15, 2015
    963
    232
    Knowing 1&2 I would have to say the inverter has a problem. 140 watts is only about a 28% load on what should be a 500 watt inverter, not very much at all. The battery when charged assuming a good battery also should have no problem. Assuming good cables from battery to inverter I would be looking long and hard at the inverter.
    How this would effect a computer is hard to say depending on the computer but I can pretty much say there is likely an inverter problem. Me? I wouldn't use it.

    Ron
     
  5. RodneyB

    Active Member

    Apr 28, 2012
    633
    13
    Are the Inverters modified or Pure Sine wave
     
  6. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,785
    945
    this sound like a cheap cigarette lighter socket type of device. I bought one to put in the car and the rating must be a max instantaneous peak value. it was rated 400 Watts, but would seriously sag to around 70-80 VAC if loaded more than 30-40 watts. ended up junking it. my laptop power supply was max. 85 watts load and it would not support the load
     
  7. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    the output transformer of an inverter is what determines the output of the inverter. a 12 volt to 120 volt inverter has a 1 to 10 ratio. if the input voltage drops, the output voltage will drop too, at a 10 to 1 ratio, 10 volts in, 100 volts out. make sure your dc wireing is heavy enough to carry the current without much voltage drop, and if the battery is dropping voltage too much, check it for capacity .
     
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