digital Clock wont keep time

Ive got my master bedroom hooked up using a morningstar suresine inverter
and my alarm clock looses about 3 mins a day. I used to have a cheap mod sine
wave inverter and my clock would run fast about 3mins a day. I researched
for a fix for the clock running fast and made the switch to pure sinewave but
now this. Ive been dealing with it by moving the clock up 5mins everyother
day but now iam wondering if maybe i have a faulty inverter. Should i contact


  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: digital Clock wont keep time

    Have you checked the Frequency with a meter or a Kill a Watt?

    Sounds like it is running a tiny bit off. What other loads are you running at night? I suppose that if you are running only tiny loads over night it might put out a little bit higher or lower hz. My MS inverter was putting out 59.6hz the last time I checked with a kill-a-watt.

    It does beg the question as to why you don't just use a cheap battery digital clock and put the inverter to sleep.

  • VicVic Solar Expert Posts: 2,933 ✭✭✭✭
    Re: digital Clock wont keep time

    Hi mr. mike,

    Most inverters use a quartz crystal to determine the output frequency. Some appear to be trimmed or set for exact frequency within fairly close tolerances, but still there will be variations when taking into account temperature and voltage changes etc.

    At my off-grid site use battery-powered clocks, altho I do miss an illunimated digital clock. But expecting an inverter to output very precise frequency over a long time is expecting too much, especially when using a fairly inexpensive inverter (nothing against your inverter).

    Even when on-grid, several of my digital colock do not keep perfect time -- things happen to the AC waveform which cause the clock to gain or lose time. If you really want to see clock errors, use Search mode !

    you might call Morningstar, and try to find their spec of freuency tolerance, and if they feel that this is out of spec.

    BTW, i have never set the clock on the propane stove, or the Microwave, so I dunno about the accuracy of my inverters.

    Good luck, vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: digital Clock wont keep time

    based on the 3min loss i figure his has a frequency of 59.875hz and isn't too bad. your only option may be an atomic clock that will right itself to the correct time if you don't want a battery operated one.
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: digital Clock wont keep time

    Sounds about normal to me. DW was happy to get a new microwave at Xmas but disappointed that the digital clock lost about 3 minutes per day.

    Fortunately the display can be turned off, and is.

    Battery powered alarm clocks are one of the sacrifices necessary to live off-grid.

  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: digital Clock wont keep time

    Better yet,,, the old wind up westclocks,

    My house is alive with the ticking of various clock devices. Wind up recording barometer, bedside clock, kitchen time, pendulum wall clock.

    (i do have a digital bedside with large numbers so I can see it without my glasses, battery operated)

  • System2System2 Posts: 6,290 admin
    Re: digital Clock wont keep time

    Thanks fellows I think i will get a battery powered clock. As far as loads go
    the only thing running at night is the 5w clock and the cordless phone stays
    plugged in and a 1157 bulb in the hallway. Thats about to change to 2- 15
    watt 12v cfl's. Iam thinking it might be better to just light the house up at night
    with 12v's and put the inverter up until i get more pv watts. Iam at 240 now.
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: digital Clock wont keep time
    mr.mike wrote: »
    and the cordless phone stays
    plugged in

    I've only had two cordless phones and when buying each of them I searched until I found units that used 12VDC for power, from the wall wart, then tied them to my 12V batt bank. Seemed like a waste to convert 12VDC to 120VAC so that it could be converted back to 12VDC.

    The first one lasted for many years, and its replacement has been in use for at least 7 or 9 years so far.

  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: digital Clock wont keep time

    One corded phone in the bedroom,,, put the cordless' on a power strip. We have a dual 12vdc system in the house so that we have 12vdc lights always even if the inverter is off or sleeping. A couple of 12vdc leds serve as night lights while drawing ~.001 watt.

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