Setting up an inverter charger as an UPS for a freezer

This video shows an experimental set up of a domestic capacity UPS for fridges and freezers. It uses a Giandel inverter charger rated at 1000w and 25A-55A with a 100Amp-Hour deep cycle hybrid battery. The freezer is small but old technology, so it isn’t particularly efficient drawing about 100 Watts or just under 10 Amps from the 12 Volt battery.

This set up automatically switches to battery power and inverter mode if the mains power disconnects, and then back to charger mode when mains power reconnects. This gives a back-up power supply sufficient for around 5-7 hours duty cycle – for me that’s enough to get home from work in time to start a generator and stop food spoiling in the event of a grid black out.

Cost of the inverter is under AUD$200 and the battery is around AUD$220.


  1. Richard Mullens on December 27, 2019 at 5:31 am

    Not a good test ! If the freezer wasn’t running when the power failed then the inverter would have to supply extra current when the compressor motor starts up.

  2. tim elkington on December 27, 2019 at 5:41 am

    very interesting clip i have done similar with larger inverters but have too build the change over relay myself

  3. Bax Bax on December 27, 2019 at 5:41 am

    Just purchased one of these inverters. What I like about them is that the input is electrically isolated from the output AND they have the internal elecrical hardware to enable them to be earthed to the ground, without having to purchase expensive RVD and RCD devices. Something that perhaps most people thinking about buying an inverter would not even consider BUT these 2 capabilities could one day save a life. Might pay to research a little about input/output isolation and inverter earthing! Sure raised my eyebrows.

  4. Philip J Ayton on December 27, 2019 at 5:50 am

    Great vid! 🙂 How have you found the Giandel Inverters performance so far? How long has it been operating?

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