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Dometic Group

MY CFX3 SAYS “!ALERT – VOLTAGE LOW” EVEN THOUGH ITS PLUGGED IN. WHAT DO I DO?

Your CFX3 has a 3-stage battery protection system that actively monitors inbound DC voltage and will turn off the cooler if it senses low voltage. This feature is designed primarily to prevent the cooler from draining your vehicle’s starter battery and leaving you stranded while out on the road. It also prevents damage to accessory batteries. The battery protection system has three levels: we recommend High or Medium for applications where the CFX is running from your starter battery, and Low when its running from an accessory or dual battery.If your battery protection is set to a recommended setting and the CFX still won’t turn on, try setting the system to one level lower – eg from High to Med. Do not use splitters, pigtails or extensions.  Each of these can create more line loss (DC voltage decreases along the length of a cable) which will cause lower voltage at the socket.  

NOTE: 

  1. When electricity (current) flows from a battery, the voltage of the battery reduces. This is known as Peukert’s Law, and commonly referred to as the voltage when battery is “under load”. This is important to understand when troubleshooting voltage issues because the CFX3 is not using the “no load” battery voltage for the 3-stage battery protection system, but rather the voltage when the compressor is running, and battery is under load.  This means that your vehicle battery may read a full 12.8V at the terminals, but when the CFX3 compressor turns on, your voltage readings will drop, and then return to the original voltage when the compressor shuts off.
  2. The voltage drop from the battery to the CFX3 is also an important consideration. Voltage is measured at the internal electronics, then calculated to equate to the voltage at the DC Plug at the end of the DC lead. This value is displayed on the CFX3 display, and in the CFX3 app.