Slow clocks with pure sine wave inverter

terrynew
terrynew Solar Expert Posts: 48 ✭✭
in Off Grid Solar & Battery Systems #1
All the digital clocks in my house, including in appliances, lose 1-2 minutes a day. This had been ever since I went off-grid nine months ago. I had thought it was just something to suffer through, but recently was told that it may be an inverter problem. The funny thing is that it's a full sine wave inverter (Magnum MA4448PAE), not a modified sine wave one that is known to cause digital clock troubles.

The specs say it outputs 60 HZ +/- 0.04%, which I figure shouldn't account for 1-2 minutes/day loss. Is there a way for me to confirm the frequency without buying an expensive scope or meter?

Any advice would be greatly appreciated. Thanks,
...Terry
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Slow clocks with pure sine wave inverter

    That should be +/- 0.57 seconds per day error.

    Assuming your digital clocks use line frequency--that should be enough to "prove" that the inverter is not meeting specifications (by the way, I cannot find a model MA4448PAE inverter--is it is a "MS" model?).

    I wonder if the frequency can be "trimmed" to meet specifications (a small justifiable capacitor to tune the frequency)?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,891 ✭✭✭✭✭✭
    #3
    Re: Slow clocks with pure sine wave inverter

    Measure with a frequency counter! A decent Fluke has one built-in. My favorite Agilent has that and an amazing ohms circuit for finding DC ground problems in noisy circuits. Kind of a 4 wire ohms meter that uses two wires and does a calulation to simulate what a 4 wire meter does. More than you need but nice to know that HP's offspring are definately still the cutting edge!

    Simple solution, use battery clocks!
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
    Re: Slow clocks with pure sine wave inverter

    I don't use 120 volt AC clocks for a couple of reasons, and suspect most others off grid don't either. First, I know inverters aren't dead on with their frequency, and second, electric clocks are viewed, at least by me, as parasitic loads. My solution? Battery operated digital clocks, then I know the time is right, especially as I have several and can compare :p
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #5
    Re: Slow clocks with pure sine wave inverter

    Even on grid, I have a couple "atomic" battery clocks (and even a Casio wrist watch). So far, they work well for me and usually receive the radio signal ever day or two (the clocks/watch need to be kept away from electrical wires/interference to receive WWV after midnight).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • terrynew
    terrynew Solar Expert Posts: 48 ✭✭
    #6
    Re: Slow clocks with pure sine wave inverter

    Oops, you're right, Bill, it's an MS4448PAE.

    The battery-powered clock solution will work fine, but I'll have to train myself to ignore any appliance clocks.

    I'll see if I can borrow a Fluke or other meter with a frequency counter.

    Thanks,
    ...Terry
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #7
    Re: Slow clocks with pure sine wave inverter

    A $15 kill a watt meter has a freq meter in it.

    I second battery clocks with rechargeable batteries in them. All we ever use.

    T
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #8
    Re: Slow clocks with pure sine wave inverter

    I would be a bit surprised if the k-a-w was accurate to 0.04% --That is only 60Hz +/- 0.024 Hz.

    A digital/analog with second hand AC clock + accurate time source measured over a week+ is probably easier and more accurate (average over time) to see a +/- 0.57 second per day frequency error.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #9
    Re: Slow clocks with pure sine wave inverter

    My k-a-w jumps back and forth between 60 Hz and 59 Hz, spending more time showing 60 than 59, so yes, it's close to 60 Hz.
    Like BB said: "A digital/analog with second hand AC clock + accurate time source measured over a week+ is probably easier and more accurate".
    A LOT more accurate! But really what's the point, we all know that inverters wonder around their design frequency. Now a $500,000.00 inverter, I'd expect to be a lot more accurate, but a battery operated clock costs much less. :p
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #10
    Re: Slow clocks with pure sine wave inverter

    Argh... I've not thought about this. TV's and VCR's and such, wow, I will need a accurate source
    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 ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #11
    Re: Slow clocks with pure sine wave inverter

    I've got one of those "atomic clocks"; receives radio signal from time base.
    Doesn't actually work at the cabin; radio signals have a hard time getting in there. :roll:
    Sometimes it doesn't get a signal elsewhere either.

    Any measuring device is only as accurate as whatever you compare it to; inevitably another measuring device. Or as Ogden Nash said: "A clock is something you check your watch against only to discover the clock is several minutes wrong." :p
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  • machineman
    machineman Solar Expert Posts: 129 ✭✭✭
    #12
    Re: Slow clocks with pure sine wave inverter

    The digital clock on my propane stove top has the same issue. Clock falls way behind but I haven't actually calculated the rate. It's always been off grid so I figured it was a proplem with the stove. I have Magnum MS-4024AE pure sine wave inverter running 21 months now without issue.

    Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #13
    Re: Slow clocks with pure sine wave inverter

    I wonder if there is a "trim" cap on the 60Hz master, that can be fine tuned....
    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 ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    #14
    Re: Slow clocks with pure sine wave inverter

    Buy a wrist watch. problem solved. or sync your computer..http://www.worldtimeserver.com

    this problem of clocks being inaccurate when run off inverters is not new and I have never found one inverter that has an accurate enough frequency keeping circuit. Its just not worth while for the manufacturer to go to the extra effort to use a trimmed crystal for frequency accuracy as most items opperate perfectly at + or - 5hz of 60 or 50 hz.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #15
    Re: Slow clocks with pure sine wave inverter

    I use pool.ntp.org for time sync on the computers.

    But the stove, microwave and VCR/DVD all have clocks, and same with clock radios . Well, I guess when I move to the ranch, I won't need the alarm clock, my PDA has that function, and cell network updates it's time. But I like all the clocks to read the same, and my watch keeps +- 20 seconds from DST to ST, so it's OK. But clocks loosing/gain minute a day, what a pain. And I'm sure they use the generic TV colorburst 3.xx MHz crystal as their timebase, what a shame if there is no way to trim it.
    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 ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • chevenstein
    chevenstein Solar Expert Posts: 100 ✭✭
    #16
    Re: Slow clocks with pure sine wave inverter

    My Magnum inverter goes all over the place when it's not heavily loaded, according to my Kill-A-Watt. I've seen it as low as 45 Hz, but never much over 60. It seems to smooth right out when I apply any load over a few tens of watts. I don't have any clocks that plug into AC so this has only been something of a curiosity to me.
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