Fridge is surge overloading inverter

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Comments

  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭

    This has been mentioned before, but make sure you have really short and heavy wires from the battery to the inverter. I would suggest #4 if not longer than 18 inches or #0 up to 4 feet. The easy way to check this is put a volt meter at the inverter and watch that input side voltage while the load is starting, if it drops to 11.0V you either need a thicker wire or a larger battery. You can measure the voltage at the battery as well and do the same thing, it is only drops to 12.0 then your wire needs to be thicker.

    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin

    Taslim,

    I believe you are in Pakistan? Do you have any inverter (or linear) compressors over there yet?

    In the USA, the inverter refrigerators are still not very common, especially in the smaller sizes. However, in many of the areas of the world, the inverter/linear compressor refrigerators are becoming common.

    Inverter/Linear compressors use a VFD (Variable Frequency Drive) that varies the output frequency of an inverter driving a (typically) 3 phase motor. Instead of high starting surge (like a normal induction motor compressor), it has a very low (almost no) starting surge.

    For your existing system, you can look at the DC input wiring to your AC inverter... Need short, very heavy wiring from the batteries to the inverter's DC input.

    Check the inverter's DC input voltage when starting--Should be over ~11.5 volts for a 12 volt FLA battery bank (or 23 volts for 24 volt bank, or over 46 volts for 48 volt bank).

    Also, you need a battery bank that is large enough to supply starting surge/energy to the inverter. For flooded cell lead acid batteries (FLA battery), that would be (very roughly) a minimum of ~600 AH @ 12 volt battery bank (or ~300 AH @ 24 volt, or ~150 AH @ 48 volt) battery bank--Typically driving a 1,200 to 1,5000 Watt rated inverter.

    One trick that sometimes works--Get a 50-100 foot light to medium extension cord (~15 to 30 meter) and plug the refrigerator into the cord, and the cord into the inverter output. Sometimes, the increase in AC wiring resistance is enough to allow the refrigerator start/run and not overload the AC inverter.

    Standard refrigerators are what usually take a "small" off grid power system to "medium" size system.

    The other thing to look into... DC powered refrigerators (typically 12/24 volt input). They have a version of VFD internally to run the compressor motor and have almost no starting surge.

    DC powered refrigerators have been around for a long time. However, they are usually very expensive and it is a close call between DC fridge+small off grid power system, vs a standard AC refrigerator and a "medium" sized off grid power system + AC inverter.

    Taslim, please feel free to start your own discussion thread. And we can discuss your system and energy needs.

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PNW_Steve
    PNW_Steve Registered Users Posts: 79 ✭✭

    FWIW: I have the same inverter and have been running a refrigerator on it for three years with no problems.

    My battery bank is two GC2's (6v, 225ah) in series.

  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭

    There are really good referigerators available that do not require a inverter, smaller than a standard household AC fridge and never with auto defrost. Since I bought mine I will not go back to AC referigerator. The newest generation uses technology patented by Danfoss of the Netherlands. These units use a DC permenant magnet motor controlled by a electronic controller. Mine will run on a 100 watt solar panel and 1 100 a.h. battery. 42 watts average draw at 10-15 volts or 20-30 volts DC. Way more expensive than an AC referigerator but the power source is way less expensive! No inverter, 1/4 or less the power use. ....... .20-.25 kWh/day........I have three now, one cool box for vegetables 42-46 deg. F one cold box for meat, dairy etc. 36-39 deg. F and a smaller frig used as a freezer 3.3 cu.ft. -20 deg. F All running on my 24 volt system.

    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
  • PNW_Steve
    PNW_Steve Registered Users Posts: 79 ✭✭

    When I was looking at a replacement refrigerator for my 5er I looked at DC refrigerators.

    The ones I looked at cost about 5x as much as the AC refrigerator that I wound up with but use half the power.

    I knew that solar, batteries and inverter would be necessary for other power needs. I simply needed to make the solar system a bit larger if going with an AC refrigerator.

    In my case the larger AC refrigerator was a better fit for me.

    It has worked well enough for me that I am getting ready to put my 3rd AC refrigerator in my latest RV project.

    If a DC refrigerator was in my budget I would still have reservations with my application. I travel and have had two (absortion) refrigerators fail when I was a long way from home. Finding qualified service and parts can be difficult to find while traveling. Getting my Frigidaire serviced is much easier. Worst case I have to Shell out $379 for a new one at Best Buy, Home Depot or Lowe's.

    Solar has come down in cost enough that things that were impractical a few years ago have become viable options.

  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    edited April 2019 #37

    I paid about $700 for a Grape Solar Glacier GS 5 at Home Depot online with free delivery to my local Home Depot, the freezer door hinge snapped at 11 1/2 months into the 12 month warranty , grape solar shipped me new one and didn't want the broken one. It was not that hard to make a plug door, push in to fit. Not bad for $700, then got the no-name 3.3 cu. ft unit from a New Peterbuilt that was totaled. Same Danfoss clone Colku from China. I got a real deal. They are getting more common now. I have a large Dometic absorbsion referigerator I use as a pantry. Not efficient at all. The grape unit replaces it. It works on gas but the AC element is burned out. And just like a Dometic...not reliable. My dc units have had no issues at all except the door which was caused by ice buildup, I live right on the left coast so my humidity soars at night and drops in the daytime, perfect conditions for excess frosting.

    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
  • PNW_Steve
    PNW_Steve Registered Users Posts: 79 ✭✭

    Wow!

    The 10 cu.ft. DC refrigerator that I looked at a couple of years ago was over $2000 with shipping.

  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭

    Yes they have come down a lot peek at green energy innovations. Very good looking dual compartment dual compressor units for $800 or so. There are two totally different sites with that name, one is a big bucks green contractor,maybe in Hell-A, the reefer people are in New Jersey.

    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭

    Sundanzer is still the Rolls Royce, but pricey.

    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
  • Taslim
    Taslim Registered Users Posts: 10 ✭✭

    My inverter leads are too short and inveter doesn't beep while starting for low battery as it has enough power from battery. Its just trips for overload protection. In my country there are many types of inveter refrigerator but i don't want to pay for new one as my old refrigerator works perfectly and it uses about 210 watts countinously on electricity. I was thinking to start its compressor by any type of ac capacitor or 500 watts bulb connected in series with refrigerator.

  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭

    A capacitor may offer some power factor correction, which may allow the inverter to support the compressor especially during the starting phase, how this will work is unknown, but power factor is a consideration with induction motors.

    The question I have is, what type of inverter is it you have, pure sine wave or modified, if modified these will not be well suited to induction motors.

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin

    Is your refrigerator use 250 watts to run the motor (typically 25 to 50% of the time)? That is a lot of power (usually use around 100-120 watts when motor running and 500-600 watts during defrost cycle one or two hours per day).

    Or is it using 250 Watt*hours per day? That is very low usage (250-1000 WH per day is very energy efficient).

    Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Taslim
    Taslim Registered Users Posts: 10 ✭✭

    It accurately uses 210 watts countinously while running compressor. This power also includes the stebilizer power. I have modified sine wave inverter. I am running ceiling fans and other home appliances like washing, spinning, blender and LED's bulb etc without any problem.so is it good to run this refrigerator on this inverter

  • Taslim
    Taslim Registered Users Posts: 10 ✭✭

    I have connected 600watt mono solar panels with 12 volt system having 150ah battery bank. How many load can i put on this in sunny days. I have movable solar panels from east to west directios which provides me full efficiency of power from 9 am to 3 pm.

  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭

    A MSW inverter can cause heating in such motor loads. They may run, but run hot. This can mean higher consumption (ie some of your 210 running watts is going to heat wire as well as what's used to actually run the motor).

    At 6hrs full sun, I'd guess production of ~600x6x75%=2700watt-hours, x80% average inverter efficiency, maybe 2200 AC wh, less whatever for MSW heating/wire loss and any poor PFs in loads (microwaves and some lighting can be .6 or so.)

    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • Taslim
    Taslim Registered Users Posts: 10 ✭✭

    Can i connect ac capacitor on output side like 50 uf or 100 uf to start heavy surge Motor for few seconds. For example i connect the capacitor first to inverter to let it charge for few second, after that is connect load on inverter. If it starts ,i remove capacitor. Will this work for me to manage surge???

  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭

    NO !

    Capacitors on AC don't affect surge, they affect power factor. Most motors come with the proper size Starting and Running caps. Sometimes, if you have the right gear and knowhow, you can fine tune the caps for that particular motor.

    motors on compressors (air con & fridge) sometimes can have a "Hard Start" cap kit installed.

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  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭

    Or you might try correcting power factor with film caps. Startup surge is usually horrendous in terms of power factor. You might end up with a setup where the efficiency is less due to the mismatch during run, but it starts.

  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭

    Be very careful that capacitors to over-correct power factor are wired directly to the supply, not after the motor switch. Ignore this and you can get some damaging resonances.

    I am available for custom hardware/firmware development