Size of inverter to start a refrigerator?

I want to get an inverter to run my refrigerator. It is a normal size
(850*600*600mm), "A" efficiency refrigerator. The running power is pretty
small - 70W I think - but I'm not sure how much current is needed to start
up the induction motor in it.

Will a 250W inverter get it started, or do I need something bigger?

Thanks

Roger

 

Once you get it started off an inverter check the servo motor for the defrost
timer. They are power picky and it may not run at all.

 

I would be very surprised if it would start on that little inverter.
Refrigerators can easily take up to 10X their run power for starting. You did
not mention what type of inverter, many refrigerators do not seem to like square
wave power (or MSW). My 'fridge (about 200 watts run power) will not start on
my little 600-watt Honda "lunch box" genny, and it will not start reliably on my
1000-watt inverter, but does run very well on my 2000-watt Honda inverter genny.

Vaughn

 

This and many other similar postings points to the necessity for a
demand-surge capacitor bank. A very common problem with alternate power is
the need for a much higher load for a brief period of time for things like
starting motors.

I'm not aware of any such devices on the market, but I'm sure a good
engineer could enlighten us.

 

The problem there is that capacitors are a DC device, and actually will
filter AC. For a capacitor bank to be of any use, it needs to be on the
DC side of an inverter, and therefore still limited by the capacity of
the inverter.

 

And therein lies the engineering challenge.

 

Joh, thanks for the kick starter tip. May want this some time in the future
for some larger drives in my future full sized application.

Agree that fridge should start with small inverter for the OP. Just need to
use decently sized wiring and securely connect inverter to battery. Then the
battery is the "capacitor" and most inverters will handle the temporary
surge. Of course, better inverters will handle more for longer.

surfnturf

 

Thanks for your comments Harry.
I wonder if you could further comment on these questions:

Does the Trace send a pulse about every second - which clicks a relay
in the fridge on/off? (I'm not talking about the normal clicking
associated with turning the motor on/off at the usual intervals)

Does the inverter shut down or go into "standby" mode at intervals
when the motor is not running?

What make is the fridge?

Does it seem to have electronics which run all the time (things such
as timers, fan etc).

Generally the small "dorm" type fridges are no problem because they
are just a compressor with a thermostat.

Any further comments appreciated.

(PS - the "super-effficient" fridge I have just remembered is a Gram)

Eric Sears.