Why oh why

Chris11Chris11 Registered Users Posts: 126 ✭✭

This past weekend we had our final family get-together of the year on our off grid property.  All went well with the lights working well in my  17 building western town.  For overnight use my Son-in-law uses a CPAP machine and the next morning I asked him if all went well with the machine.  (For this CPAP I was able to connect my 1000 watt inverter.)  He replied that it worked until about 4 AM when it shut off.  I really like my SIL so I don't want to kill him.
I checked the batteries with a hydrometer and found both end ones in  the 4 in series were at their normal 1.300 reading, which seemed strange after 4 or 5 hours of light bulb usage in many of the buildings PLUS 4 or 5 hours of CPAP usage, and equally strange was the two center batteries were at 1.250.  I did a full charge as the  sun rose then did 3 one hour equalizations which seemed to fix the glitch.  By the way the next night his CPAP worked perfectly all  night but I did connect his hotel room to my 2500 watt inverter in case the inverter was the problem.
All three inverters seem ( I failed to mention the 500 Watt one I also use for smaller loads ) to be working well

My simple question is why did the 1000 Watt one shut off ?  Im suspecting that lack of doing my equalization routine over the past few months caused this since doing 3 hours worth seemed to fix it.   Possible?


  • WaterWheelWaterWheel Registered Users Posts: 362 ✭✭✭
    I'm wondering why you refer to a SG of 1.300 as normal.        What type of batteries are you using?   

    Conext XW6848 with PDP, SCP, 80/600 controller, 60/150 controller and Conext battery monitor

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  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Few CPAP machines require more than 100w unless heaters are being used.  Running your smaller inverter will consume less power overall.  A well built 500w inverter consumes less internal power than a 2500w inverter.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
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  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    Is the 1000w inverter a pure sine wave type, or a modified (square or step) wave type?

    With some loads, MSW inverters induce heating or other problems in the load. Purely resistive loads like heaters are generally fine, but other loads with motors, electronics, etc can have trouble.
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
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