Not PURE enough? Need inverter help!

I am finishing up installing my off grid system. 710 watts of panels, Solar boost 50 controller and 270ah of batteries.

I just bought and installed an AIMS 1500 watt pure sine inverter. My main reason for needing a clean sine wave are the washer/dryer stack and possibly a window air conditioner. Both of these run well on my Onan generator, but do not like my smaller generator.

The washer will run on the inverter, but the dryer does not even attempt to start, much like when using the small generator.

Voltage and current are not the problem. I am getting full voltage to the inverter on startup of the dryer. The dryer is gas, so the current draw is small. 600watts on startup, 300 on run. The washer which runs ok, is 450watts on startup and 200 on run. Not big enough of a difference.

I am guessing that it is a matter where I got what I paid for, but before investing in something else trying to fix the problem, I figured I should ask around.

So my questions are: What are you using that works? What is the grade of the waveform on various brands?


  • KamalaKamala Solar Expert Posts: 452 ✭✭
    Re: Not PURE enough? Need inverter help!

    I use a ProSine 2.0 (2KW) by Xantrex. But I am not (so far) employing inductive loads. In selecting an inverter for my camper, I only considered Xantrex and Samlex/Cotek.

    I just installed it on 08/01/09 and inaugurated it by popping corn in the micro (inductive?) We enjoyed watching the battery monitor's amps display jump from 6A to 104A for 2.4 minutes. Worked great. I can't endorse the Xantrex product based on only 1 day of use, but I can say that it is a quality product and the manual alone probably accounts for 2% (where's I get that from?) of the price <$1400.

    One of Xantrex's tag lines regarding "purity" of waveform is "better than your power company" or some such.

  • BB.BB. Super Moderators, Administrators Posts: 31,629 admin
    Re: Not PURE enough? Need inverter help!

    On the drier--Do you know if it is a spark or "glow bar" type ignitor?

    The Spark Type Igniters typically need a ground neutral to work correctly (at least in my limited experience).

    300 watts running and 600 watts "starting"--Is that first turning on and moving the drum, or during the ignition cycle?

    I don't remember the specs. for a glow bar--but they do take 300+ watts as I recall... If the voltage is poor (RMS voltage, not all meters can measure True RMS--they measure an "average" which, with MSW inverters is not very accurate).

    If the bar is getting low voltage, or beginning to fail (crack/burned spot beginning to limit current)--it will glow--but not quite "white hot" enough to light the gas.

    Is the drier not lighting, or not running?

    You will need to check with AIMS or their manual to see if they support grounded neutral (with a grounded "-" battery lead). Many MSW type Inverters cannot (they let out the magic smoke when the battery "-" is grounded with the AC "Neutral" (again, this is most important for spark type systems).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Not PURE enough? Need inverter help!

    The problem is with the motor starting. Push the button and the motor hums. The glow bar doesn't kick in until later, and it adds about 200 watts and is off most of the time.

    Thanks for the heads up on the battery negative problem. I tried it with an extension cord before wiring into my system. Maybe that was a good thing as my whole house is wired with the AC and DC bonded to the box.

    My voltage reading was with an old Robinair meter and it showed 122 volts on the output while running the washer load. My experience with square wave has been that it showed up at about 85 volts on an analog meter. I don't have any experience with modified or pure sine inverter voltage up until now. I don't have an RMS meter, but do have a scope, so I can look at it that way and see how smooth the waveform actually is as well. Just haven't gotten that far.

    I thought about buying a Xantrex Prosine, but opted to save about $800, so here I am.

  • BB.BB. Super Moderators, Administrators Posts: 31,629 admin
    Re: Not PURE enough? Need inverter help!

    Have you measured the V*A of the drier? A very handy meter for 120 VAC is the Kill-A-Watt... Measures both VA and Watts (and PF, plus kWhrs, etc.).

    The only things I can think of are:
    1. Inverter is really much closer to MSW (would be interesting what the o'scope shows). Check inverter frequency (probably not not problem).
    2. Drier has poor Power Factor. If PF is closer to 0.5, VA is closer 1,200 VA, may be close to inverter's VA limit (which should be equal or greater than 1,500 Watts/VA)-- Inverters will limit VA>max just like Watts>max
    3. Drier motor start capacitor is bad--or too small (larger cap can give better starting torque).
    4. Check DC input voltage on inverter--Wiring voltage drop or battery sag maybe too great.
    5. Motors can have very large starting currents (high VA, not high Watts)--may just be outside the ability of the inverter to start.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: Not PURE enough? Need inverter help!

    The idea of using a glow bar ignition dryer on a ~700 watt PV system seems a bit excessive. Let's assume for the moment that the glow bar runs for 10 minutes per load. 200*.6= 120 wh. Let's also assume that the motor draws 75 watts for 1.5 hours/load would be another 112 wh making a total of ~232 wh per load.

    That 232 wh would translate to ~20 ah from the battery bank or about 7% of the total ah capacity.

    Now take my "rule of thumb" for a battery based system. Take the 700 watts of Pv/2*the number of hours of good sun (~4 usually) leaves 1.4 kw day on average available into the battery bank, or about 16% of daily input,, just for 1 load in the dryer.

    It just seems to be a pretty hefty draw on a fairly small Pv/battery system. Add in the washing machine which I would guess would draw about the same wh per load or a bit more and you are close to 1/2 of your daily input. ( A 500 watt small window A/C unit would only run for ~1-2 hours on the remainder of your daily capacity).

    My hunch as to why the dryer isn't running is that the big starting draw is giving the inverter too low a voltage.


    PS I realize that my response was not asked for so, take it as you will,, just my opinion.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Not PURE enough? Need inverter help!

    I see two things wrong here.

    First of all, a dryer motor usually uses less current than a washer. Washers have to move the clothes in a tub full of water. Why is this dryer drawing so much? What does the spec plate say for power usage? And what does a K-A-W say for V/A?

    Second, unlike starting batteries deep cycle batteries don't like to put out high current in an instant. It is entirely likely that the battery voltage is dropping significantly when the dryer tries to start.

    Of course, it could just be that all AIMS inverters are poor-quality and don't live up to manufacturer's specifications. They wouldn't be the only product to fall into that category.
  • PhotowhitPhotowhit Solar Expert Posts: 5,565 ✭✭✭✭✭
    Re: Not PURE enough? Need inverter help!

    I've got a tiny 24 volt 210 AmpHour storage. If yours is 230 AmpHours at 12 volts that is truely tiny and the it would be interesting to see what the voltage drop is when the dryer starts up.

    I regularly run a Window AC once my batterys are fully charged during the day, I can't recall exactly the wattage, It's 5300 btu and I think on paper says it draws 500 watts and change, though the Kill-A-Watt meter says 440watts (from memory)

    I originally ran this on a cheap Ebay 1400 watt stackable "semi-Sine wave" inverter and it ran fine, about a year ago I switched to a 1800 watt Prosine inverter.

    My bet is the start up capacitors are dead or dieing. if the Aims is a charger/inverter (handy if you run a generator and worth thinking about) start it while running off the generator and switch to running off batteries. I believe most will switch in a couple cycles, others here would know if this would be viable.

    Good Luck.

    FWIW - the cheap 1400watt stackable inverter is no longer sold, the fan went out on it after a year and it lived for another year with it gutted open and a small 6" fan blowing on it during summer, finally something shorted out, a couple wasp bodies were found near the shorted area. It ran for maybe 2 years total not bad for @$100 Someone is selling a 2500watt version now that is stackable, likely a bigger version of the other... They make a 48volt version if I was switching to a 48 volt system I'd pick one up in a pinch, I might still get a 24 volt version for a backup now I don't have(or want) a generator(I like to have spares and currently only have 12volt MSW inverters as spares)

    My inverter lives outdoors(OK in an unheated/AC shed/thingy) which was my reason for going with the prosine as it's original design was for marine enviroments and it handles heat pretty well. Something else to consider...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former, 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: Not PURE enough? Need inverter help!

    What is the battery voltage right at the inverter when this happens? Just take a simple DC meter and watch it. If it drops to 11v or less meter it again right at the battery, if it drops the same you wiring is like ok from the battery to the inverter and the battery is not able to handle the starting load. If the at the battery the voltage doesn't fall as far then the wire between the battery and the inverter needs to be larger.

    People often overlook the DC side wiring and think; well it's a sort run so #10 should be fine. But even dropping a 1/2 volt with a 12v battery is often enough for the inverter to shut down.

    Or it could be a combination of the battery and the wiring on the DC side.
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • interd0ginterd0g Registered Users Posts: 7
    Re: Not PURE enough? Need inverter help!

    I don't think it is looking for purity . More likely its looking for brute strength. I went through a simlar problem trying to run a small washing machine off the older 2.5kw Trace 'modified square wave".
    The system ran a 1.5HP water pump no problem but the washing machine wouldn't get rolling.
    It seemed stiff to me and, suspecting shipping damage ( everything in Antigua is damaged), i took it apart and found nothing. Its never been quite the same.
    I ran the supply to the outhouse in #6 twin and then it was OK.
    Voltage drop during the locked rotor moment must have been excessive.
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