wildebus
Forum Member
My campervan will have no Gas on-board so a 3-way Fridge is neither an option or something I would want anyway, so Electric-only is my solution.
Due to the high price of DC Compressor Fridges, after some research I decided to install an AC Compresser Fridge. This post (and some future followups) will show the kind of power usage to expect and if the Electrical setup is sufficient. (My own will be I know but this analysis may be useful for others interested in a similar option.
Fridge: Class A++ 94L Fridge with icebox - £170
(Class A/A+ are available for less, but significantly less efficient. A 12V DC Fridge of comparable size will be around £700)
Inverter: Inverter used for testing is a 1000W Pure Sine Wave Inverter ~ £120
very unspecial Inverter by David, on Flickr
(The Inverter for regular running will be a Victron Pheonix 12/500 PSW Inverter which is more efficient but also - critically - noiseless)
Below is a video showing power draw into the Inverter (so it includes the energy overhead cost of the inverter as well as the power the Fridge is using). Before Video started, fridge temp dial set to off, Fridge unplugged and Inverter was turned off.
[video=youtube_share;T9JE46VwWxc]https://youtu.be/T9JE46VwWxc[/video]
The times below show the event changes during the video - you can see what is causing the power use to go up and down.
Times:
0:05 - Inverter Switched On
0:20 - Fridge Plugged in
0:30 - Fridge Door Opened (so Light comes on)
0:41 - Fridge Temp Dial turned to Max - Compressor In-rush Current comes on
0:45 - In-Rush Current ends
0:53 - Fridge Door Closed (so Light off)
Note that the power use you are seeing from 0:45 is the maximum power draw all the time the fridge is actively cooling, which is a small percentage of the time on a Compressor Fridge (this is what makes them so efficient in use)
After the video ended I changed the temp dial setting to the normal running one
The Power Monitor in the video records both instantaneous power use and also cumulative power over time. I reset it before commencing the test so can check what power has been drawn by Fridge+Inverter over time.
This testing is being carried out in the winter in an unheated Camper. In warmer weather the Fridge would have to work harder and so use more power, but the same is true of any Fridge of course. When Weather permits I will repeat the experiment.
Notes:
The in-rush current occurs on Compressor Fridges, both AC and DC - this high albeit very short current spike is why it is so important to wire up a DC Compressor Fridge with substantial cable (4mm+ depending on length of run) even though the provided specs of a 12V Fridge might imply a much thinner cable is sufficient with a quoted 3-4A current draw.
If the only use of an Inverter is to run an AC Fridge, that extra cost might make this option not as price-attractive, but if your Camper is using the inverter for other purposes so you will have it anyway, there is no additional cost incurred.
Due to the high price of DC Compressor Fridges, after some research I decided to install an AC Compresser Fridge. This post (and some future followups) will show the kind of power usage to expect and if the Electrical setup is sufficient. (My own will be I know but this analysis may be useful for others interested in a similar option.
Fridge: Class A++ 94L Fridge with icebox - £170
(Class A/A+ are available for less, but significantly less efficient. A 12V DC Fridge of comparable size will be around £700)
Inverter: Inverter used for testing is a 1000W Pure Sine Wave Inverter ~ £120
very unspecial Inverter by David, on Flickr(The Inverter for regular running will be a Victron Pheonix 12/500 PSW Inverter which is more efficient but also - critically - noiseless)
Below is a video showing power draw into the Inverter (so it includes the energy overhead cost of the inverter as well as the power the Fridge is using). Before Video started, fridge temp dial set to off, Fridge unplugged and Inverter was turned off.
[video=youtube_share;T9JE46VwWxc]https://youtu.be/T9JE46VwWxc[/video]
The times below show the event changes during the video - you can see what is causing the power use to go up and down.
Times:
0:05 - Inverter Switched On
0:20 - Fridge Plugged in
0:30 - Fridge Door Opened (so Light comes on)
0:41 - Fridge Temp Dial turned to Max - Compressor In-rush Current comes on
0:45 - In-Rush Current ends
0:53 - Fridge Door Closed (so Light off)
Note that the power use you are seeing from 0:45 is the maximum power draw all the time the fridge is actively cooling, which is a small percentage of the time on a Compressor Fridge (this is what makes them so efficient in use)
After the video ended I changed the temp dial setting to the normal running one
The Power Monitor in the video records both instantaneous power use and also cumulative power over time. I reset it before commencing the test so can check what power has been drawn by Fridge+Inverter over time.
This testing is being carried out in the winter in an unheated Camper. In warmer weather the Fridge would have to work harder and so use more power, but the same is true of any Fridge of course. When Weather permits I will repeat the experiment.
Notes:
The in-rush current occurs on Compressor Fridges, both AC and DC - this high albeit very short current spike is why it is so important to wire up a DC Compressor Fridge with substantial cable (4mm+ depending on length of run) even though the provided specs of a 12V Fridge might imply a much thinner cable is sufficient with a quoted 3-4A current draw.
If the only use of an Inverter is to run an AC Fridge, that extra cost might make this option not as price-attractive, but if your Camper is using the inverter for other purposes so you will have it anyway, there is no additional cost incurred.
Last edited:
it is a little (just a wee bit :scared: ) skewed to "you must get a Sterling Inverter/combiner/whatever and was misleading on performance of other competitor's makes, but ... the Fridge part is good 