From: muratlanne@gmail.com   
      
   "Vaughn Simon"  wrote in message   
   news:pn9ec2$9c7$1@gioia.aioe.org...   
   > On 9/11/2018 3:39 PM, danny burstein wrote:   
   > In my experience, there are three possible problems with   
   > refrigerators on inverters:   
   > 1) Some refrigerators don't like square wave and modified square   
   > wave inverters.  You don't know until you try.   
   >   
   > 2) The inverter must be big enough to handle the compressor starting   
   > current, which may be several times its running current.   
   >   
   > 3) As already mentioned, the defrost cycle on a frost free   
   > refrigerator or freezer can cause a very heavy load because of the   
   > defrost heaters. I have seen 800 watts!   
   >   
   > Really, you don't know for sure until you have tried a particular   
   > refrigerator with a particular inverter.   
   >   
   > Vaughn   
      
   1) The unsubstantiated rumor I heard was that modified square waves   
   might overheat the motor and shorten its life.   
      
   2) The starting surge is proving hard to measure. I can take DVM peak   
   hold or storage scope readings but they aren't consistent, and the   
   compressor has to wait quite a while for the pressure to equalize   
   between starts.  Maybe the useful test is to watch for a voltage dip   
   on an analog meter or with a light bulb, since I don't really know how   
   much starting surge current the inverter can tolerate either.   
      
   The Summit's starting current is roughly consistent with the cold   
   resistance of the PTC thermistor in series with the start winding, as   
   measured across the AC plug.  The Magic Chef's initial current appears   
   to be lower than the resistance would suggest.   
      
   The Alpicool C20 DC-powered fridge/freezer soft-starts gradually. I'd   
   be more impressed with it if it had better insulation and didn't fault   
   occasionally.  Condensation forms on the outer walls if I add too much   
   external insulation.   
      
   3) My three small fridges are all manual defrost. On older units the   
   defrost timer motor could be temporarily disconnected when running on   
   batteries, at the risk of clogging the evaporator and its fan with   
   ice.  I don't know about modern ones. These manual defrost units put   
   the evaporators inside the walls so frost buildup isn't as much of a   
   problem.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)