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Small Cabin Forum / Off-Grid Living / Ceiling Fans
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gcrank1
Member
# Posted: 2 Feb 2021 10:31
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My cabin came with one, a 120vac typical, cheap, house type, mounted up but not wired. When I decided on using only 120vac inverted from my bat-bank I wired it up and found it runs slower and 'growls' on msw inversion, just fine on psw.
I wondered how much juice it uses running, not the start up since that is short, and I dont have a Kill-o-watt meter.
I found this article online from Jn 29, 2019 on the afresherhome.com site:
'How much elec does a ceiling fan use'
It is very good.
Short story is that motors that run stuff like a ceiling fan need to be 'power factor corrected'; ie, add some more amps draw because creating the magnetic field for the motor to make it work takes more than the label indicates (a PF chart for some appliances is inc.). Imo the author used a decent methodology for his testing and PFC his fan used:
Low 12w 0.17a
Med 42w 0.58a
High 47w 0.65a
All under 1amp at 120vac, thats pretty good.
But, for us off-gridders who are inverting off a bat-bank, often 12v we need to multiply those amps draw by 10 (12x10=120) and factor in the inverter efficiency (mine is rated at 85%) to see what we are really pulling off the bat-bank.
Thus, at 12v, the fan draw rounded up (I always round up for draw calcs):
Low 0.17a x 10 = 1.7a + 15% = 2a 'real world likely'
Etc.
Yeah, not all fans are going to be the same, either, but this gives me a better sense of how to figure my bat-bank sizing and dod, etc. while I contemplate from my easy chair this winter.

Steve_S
Member
# Posted: 2 Feb 2021 18:57 - Edited by: Steve_S
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I will point out that Modified Sine Wave is never recommended for ANY type of motor. Yes they may run, yes they will "growl". They will run at 2X the temperature & heat up quickly, it will shorten the lifecycle greatly and the feedback in the circuits will be "felt" by everything else on the entire electrical system.

BTW: If using a Mod Sine Wave Inverter, look at your lightbulbs... see what an Incandescent & an LED bulb do then compare with how they perform with Pure Sine Wave.

A vast majority of Inverter Generators are also only Modified Sine Wave, only a few like Honda (and that level) are Pure Sine Wave.

Pure Sine Wave is also a tad odd, as there is Low Frequency & High Frequency variants. Low Frequency with large copper wound coils are the most suitable and can typically handle 3X surges. So a 2000W LF Inverter will do 6000W surge handling while a HF Inverter will only do 2X surge handling. There are also Caveats to HF and Motors, see below.

https://www.magnum-dimensions.com/knowledge/high-vs-low-frequency-inverters/inversion -methods-explained-high-frequency-vs-low

ICC
Member
# Posted: 2 Feb 2021 19:48
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Quoting: Steve_S
I will point out that Modified Sine Wave is never recommended for ANY type of motor.


Yes, that is very true but it does seem to be ignored by many people much of the time. Microwave ovens don't work all that well on MSW either.

Steve_S
Member
# Posted: 2 Feb 2021 20:02
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Ohhh My, you mentioned the Nukelators !
I did it ONCE and that was once too many times for the Panasonic Inverter Nuker - it never worked properly again and went to trash. Had to, it was an emergency situation and I used a 3kw "Car Inverter" thinking it would be ok... WRONG ! 90 seconds and it was finished.

paulz
Member
# Posted: 2 Feb 2021 20:23
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So what does run on MSW correctly, anything?

ICC
Member
# Posted: 2 Feb 2021 21:07 - Edited by: ICC
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Incandescent light bulbs, resistance element heaters that sort of thing. No motors, no electronics. Though it can also depend on the item, the way it is made, type of motor. I gave up on MSW years and years ago.

Everything we buy that operates on house power is designed for use with power grid pure sine wave power. Some things just complain more on MSW or refuse to work or get damaged.

scott100
Member
# Posted: 6 Feb 2021 00:15 - Edited by: scott100
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For the ceiling fan we use most of the time, we sprung for a energy star rated dc motor unit. It is a lot more efficient than a standard ceiling fan, but at low speed a standard ceiling fan isn't exactly an energy hog either, as you found out.

Funny thing about microwaves. We have an Aims 3000 watt pure sine inverter. I noticed the clock on the microwave loses several minutes a day. Weird, I thought, so I measured the inverter frequency. It's just a tad less than 60 hz, off exactly enough to account for the missing time. Not off enough to be out of the allowable error in the spec sheet, so it was a keeper, I guess.

Steve_S
Member
# Posted: 6 Feb 2021 04:04
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The AIMS are not actually outputting exactly 60Hz, which you can easily verify with a Kill-A-Watt meter which shows the Hz of the 120V line.

Over 60Hz, clocks = faster.
Under 60Hz clocks = slower.

If using a Genset to charge batteries & provide passthrough, the inverter/charger will pass through the Genset Hz Frequency as well. so if the genset is running at 62Hz your whole system will see that while the genny is running & charging while also providing passthrough power.

Lower Cost Inverter Generators which use High Frequency Pure Sinewave electronics can also vary in Frequency beteween 58-62Hz pending on loads and electrincs quality.

gcrank1
Member
# Posted: 6 Feb 2021 10:52
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Does that mean my 700w $50ish when new microwave will likely die a premature death running exclusively on my inexpensive Champion 2000w (1700 continuous) psw inv/gen?

paulz
Member
# Posted: 2 Apr 2021 14:34
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Ceiling fan time for me too since I'm working up there (15'). Ran wiring yesterday.

I was thinking 12v but I don't see any on the market with lights. Plus they are $100-$150 (I have one of those small cheap 12v jobs elsewhere, works good but too small for this ceiling).

Also have an AC house one, the big brass things with lights that looks like it belongs in the Versailles and weighs 50lbs. That would look OK up there. And I now have a FSW inverter. Maybe that's the plan...

gcrank1
Member
# Posted: 6 Apr 2021 19:25 - Edited by: gcrank1
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This past week I became convinced I had a battery issue. During day use of the fan Ive been having the bat-bank depleting, that should not be on a sunny day! The solar should easily be running the cabin light duty loads with no bat-bank drain whatsoever, leaving a full bb for evening use.
A load tester was borrowed and one of my 2 big, old agms is toast, the other tested quite good yet. The bad one was compromising the good one, just like those in the know say (duh on me!, but I had wanted to see how far I could go with these).
Removed the bad one, the good had a solid day of prime solar charging and the next day until 11am, cc was on float when we arrived and bat tested fully charged, I switched on the 300w psw inverter.
I turned on my little fan and 2 led 9w 120v lights then checked the cc panel. The change from no load to that load read 3.2amps, close, but less than I had calculated (great!). That was all being driven by the solar, no discharge on the battery at all.
We left about 5pm, I shut down the loads at 4 pm and always discon the inv., we would have had a full bat for the evening hours (and we have no overnight loads).
This is a pretty bare bones set up but comfortably adequate. Knowing I can read my loads when I have a fully charged battery will be handy.
One may ask,"how do you know you didnt draw some off the battery?" Well, that hour between 4 and 5pm the battery was in a resting mode, no load (other than being hooked up to the cc which has a small draw), no charging taking place. When I checked it at 5pm with my multimeter it read 12.9v. That says fully charged at rest to me.

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