Small 'frige connected to inverter power draw inconsistency

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SkinnyCow
SkinnyCow Registered Users Posts: 10 ✭
in Solar Beginners Corner #1
Hi,

I have a small frigidaire wine cooler connected to Xantrex prowatt 2000 which connected to 175Ah battery using 4/0 cables shorter than 2 feet. When the frig starts up, the inverter shows 800w (0.80) then back down and stable at 40w(0.04). This is consistent with what describes in the frig power consumption. However, after running overnight and the battery is down to about 12.6 volts, the inverter didn't show any wattage (0.00) when the frig started and a couple seconds later, it showed 40w. The frig was still running but I'm concerned because I didn't see the power surge on startup. Is the inverter at fault or is there something wrong with the battery?

Will this Xantrex prowatt work and preserve the longevity of the frig or will it damage the frig's compressor in the long run? Any one has this inverter connecting to refrigerator for a few years without problem?

Thanks in advance.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: Small 'frige connected to inverter power draw inconsistency

    The inverter probably can not read the start surge under normal operating conditions because it is too brief to register. At other times, however, the power demand of the compressor will remain high enough long enough for the inverter to pick up at least an averaging of it (the 800 Watts).

    Motors are tricky things. In free air (no load on shaft) the start surge of an induction motor may be only 3X running current, and brief enough to not show unless you have a really expensive meter that samples at a very high rate. Under a load such as a compressor (which is what a refrigerator is) the start surge can be 5X running or even more, and can last long enough that it will show on just about any meter. It all depends on how much effort the motor has to make for how long in order to get up to speed. Refrigerators and other similar devices do not have consistent start-up demand owing to changes in the coolant pressure. Post-defrost, for example, will not only cause high start demand but will also increase running demand for awhile. It isn't anything to worry about.

    Your ProWatt is a pure since inverter and will not damage the refrigerator.
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  • Wxboy
    Wxboy Solar Expert Posts: 70 ✭✭✭✭
    #3
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    Re: Small 'frige connected to inverter power draw inconsistency

    I have a Xantrex Prowatt SW2000 and I've run a refrigerator, dehumidifier, tv, small AC and just about anything else I could find on the inverter. It's a great little inverter that doesn't get talked about much but it's got very low self power consumption and it's very quiet. The fans hardly ever need to run. It's currently my back up inverter but it's a great inverter for the price. Don't worry about it hurting the fridge. As Cariboocoot mentioned the surge doesn't last long so it won't always register and the fact that the display fluctuates between voltage and watts doesn't help the situation.
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