AC Fridge In Campervan -.Power Consumption Test

[oldish hippy]

would fitting a child lock help as to make sure it is sealed tight when door is shut and usefull when travelling

 

[wildebus]

would fitting a child lock help as to make sure it is sealed tight when door is shut and usefull when travelling

That is a downside of fitting a fridge that is not expected to be going round corners!

I have a neat little lock that works very well. Purchased from Amazon ...
Lock by David, on Flickr

 

[wildebus]

Inverters are seen as having an energy overhead just by being on (and they do indeed, but the amount is often exaggerated) and after setting up my electrics to be accessible via an internet portal, I am getting information on a 30 minute cycle and can really see what is happening!

So although Fridge is now unplugged for a while while I am building out, I have my 12/500 Inverter on permanently, providing power to the in-vehicle network router and monitoring computer.

I thought this following screenshot might be of interest, which shows the voltage drop overnight - the only thing in use is the Inverter and devices plugged in as described above, plus a Battery Monitor (BMV-712) and Battery Temp & Voltage Sensor with Bluetooth Connection

Clarenceovernight by David, on Flickr
The Battery Voltage (blue) is high while the Solar Panels are getting light (when orange line is >0. Battery Current = current INTO battery from MPPT Controller), but the interesting bit is between 7:30PM and 6:30AM, where there is no charging occuring, and with an inverter powered up throughout the night, the voltage drops from 12.78V at 7:30PM finally down to 12.76V by 6:30AM - so a reduction of 0.02V.

It has been suggested about using some kind of timer to turn off the inverter automatically between certain times and is something I had considered as while I have had some info on high and low voltages, never had access to a proper overnight graph. Now I do, I don't think it is something that needs any more thought over, at least as a way to save inverter overhead.

 

[nick23]

At Night

Could you not just turn the fridge off at Night when you go to bed :goodnight:

 

[wildebus]

Could you not just turn the fridge off at Night when you go to bed :goodnight:

I could



If I wanted to



Or if I needed to



Do you turn your fridge off overnight? The problem with the idea of manually turning a fridge off is remembering to turn it on again. With my very efficient 240V Fridge and inverter it is clearly not a problem I need to worry about

 

[colinmd]

Be interested to see power consumption and voltages at moment with the hot weather making the fridge work harder, but solar getting plenty of sun.

 

[channa]

I could



If I wanted to



Or if I needed to



Do you turn your fridge off overnight? The problem with the idea of manually turning a fridge off is remembering to turn it on again. With my very efficient 240V Fridge and inverter it is clearly not a problem I need to worry about

Valid point, but I guess you could fit a timer so the fridge shuts off when ambients are cold at night and set it going again in the morning..as you say not a problem to yourself but perhaps a remedy with a less robust set up

Channa

 

[wildebus]

Valid point, but I guess you could fit a timer so the fridge shuts off when ambients are cold at night and set it going again in the morning..as you say not a problem to yourself but perhaps a remedy with a less robust set up

Channa

You are quite correct.
AC Timer Switches are very easy to get and cheap as well. DC ones not so common however.

There was an earlier post with a link to a little device that has a temp probe connection and you could set to turn on if the temp rose above the preset. A neat little device, and I actually have bought a similar unit (will do a post on it in a while once everything is set up) to control a little 12V fan that will be directed at the compressor.
It would be very easy to have the temp probe inside the fridge and the output of that device going to a Relay that turns an Inverter on and off. Overnight with the fridge door closed and the ambient temp dropping, chances are the Fridge would be cool enough to have it off and so the Inverter would be off (and so the inverter losses that people worry about also gone).
As a bonus, the chances are the control via this would be better than a lot of Fridges internal dial temp which always seem a bit flaky.

I hope the above makes sense (sometimes converting what is in the head into typed words is not always that successful!), but in essence, if someone has a rig that is top-heavy with Solar and under-weight on the battery side, this would be in all likelyhood a decent option for summer use.

 

[wildebus]

Be interested to see power consumption and voltages at moment with the hot weather making the fridge work harder, but solar getting plenty of sun.

Fridge not been on for a couple of weeks as I build my galley kitchen, but hopefully in the next couple of days it will be plugged in again :cheers:
Not got any real load in the camper right now other than the Inverter running the Raspberry Pi and an Router/Radio Intranet.
About to plug in a Mains Battery Charger into the Inverter (sounds weird I know) to charge the Starter Battery as I have a highish drain on it (I think due to the Tacho, for which I cannot find the fuse to disable ) so that will add a extra load - but only minimal though.

But due to the minimal load (around 500W a day average), the batteries are at Float for most of the daylight hours.
mpptstate by David, on Flickr

Each day the Bank drops to a low of around 98.5% SOC by first light but back to 100% within an hour

 

[wildebus]

Out of curiosity decided to plug in the fridge tonight and do some random checking ....

So at 18:30 Fridge plugged in. Internal Frdige Temp was 24.4C; Ambient Temp was 25.7C

Loads on Leisure Battery are:
Victron 12/500 PSW Inverter +

230V Compressor Fridge
Victron 12/20A Mains Battery Charger (output to Vehicle Battery)
230V Ubiquito Router and Radio (Wi-Fi Booster)
​

Direct DC Loads

MaxxAir Fan; set at 50% and set to close when internal temp drops to 20C
Raspberry Pi (via 12V-USB 3A Converter) Monitoring Computer
Small Hot/Cool Fan Controlling Unit (for extra fridge fan but set high to avoid kicking in during test)​

Total load of all the above at 18:30 - 65W

As I am typing this (2 hours later) the load has dropped to 25W and the fridge has reach set temp (put dial to "Med" - not sure yet what temp that is)

With the Fridge operating within a much warm ambient temperature it will be interesting to see how it goes

 

[wildebus]

Be interested to see power consumption and voltages at moment with the hot weather making the fridge work harder, but solar getting plenty of sun.

Following on from last Post, here are some charts which may be interesting?


Now I have 440Ah of Batteries and the State of Charge (SOC) went down to 95.8% at the lowest point (again, at first light as it always will be). So 4.2% taken out of the battery bank total power.

Fridge-SOC by David, on Flickr

If someone has the same setup, but just a single 110Ah battery, that would take their SOC down to 83% (17% worth used).
This is over approx 12 Hours.
If we assume no battery charging (e.g. no Solar or Hookup) then a full day would double that, so on MY setup, the SOC would be at 90.4% and the 110Ah setup would be down to 66% SOC.
Conclusion there? As you don't want to ever go below 50% SOC on most Leisure Battery installations, you Can't run a Compressor Fridge off a 110Ah battery for more than a day without supplementary battery charging (e.g. Solar).


This is how the power is being consumed in the camper (loads noted in previous post)

Fridge-BattW by David, on Flickr

I think the increased load between around 14:00 and 19:00 is my roof fan? I turned the speed down around 7pm when I closed the van up (but don't think the fan shut off at all overnight as I expected it to, as the remote control was in the wrong place!).
You can see the peaks of power as the compressor comes on every so often. The close peaks around 21:00 will be while it is coming down to the set temp (2C looking at gauge this morning). It would seem the compressor doesn't constantly run while the temp needs to drop, but just kicks on and off much more frequently?
Note those peaks look dramatic but only actually represent an increase of 40W (open the fridge door and the light coming on draws 10W!)


Final Chart shows the Battery Voltage over time and the NET current drawn

Fridge-BattV&C by David, on Flickr

I've added a red line to this chart - if the (orange) current line drops below the red, it is net current OUT of the battery and when it is above the red, it is new current INTO the battery (i.e. Solar is providing more than the load on the battery).
So it is getting light around 6AM, but due to trees and buildings it is only around 8:00 or later any clear sunlight (so noticable harvesting) comes in.
With the Solar Charging the batteries, it is back to 100% SOC at around 10:30 AM
the same level of charging and time to return to 100% SOC would be true of the 100Ah battery as well, as the same power was taken from both overnight.
If there was less Solar on the roof than my 400W Array, then the time WOULD be longer; However you could/might park in a better position for harvesting (if I moved my camper just 15 foot NNE, I would get MUCH better solar performance), and it is dependant on cloud levels as well of course, so estimating time to return to 100% SOC is nigh on impossible.
BUT I think it is safe to say that generally what you use overnight from the battery will be replenished during the day.
Comparisons:
a 100Ah Battery contains approx 1200Wh of TOTAL Power (P=IV == 1200Wh = 100A x 12V) which equates to 600Wh of usable power (I am simplifying this and ignoring Peukert's law for any one who wants to get picky)
A 100W Solar panel in the Summertime should bring in more than 600Wh of Power in a day I would say. As an example, today my 400W array has brought in 500Wh upto just before noon. Thats 125Wh per 100W panel in around 4 hours. Extrapolate to 16 hours of daylight and at 500Wh per 100W panel. Park in a better place and it will be significantly better.


I had a Weaco CRX-50 in my last camper, with 220Ah of Batteries and 200W of Solar. I would get back to full charge and the battery in float mode by mid-morning. That 12V Compressor Fridge is less efficient than the 230V Compressor Fridge I have now based on all my testing of both units.
(If Dometic wants to send me a 12V CRX-80 to do the same testing that I have done with this Household Fridge, I would be happy to do so )

 

[wildebus]

Quick little update and recap ....

So the Fridge Compressor seems to come on for a set time (about 5 minutes) and then go off again. This bit is a constant and what changes is the frequency of how often it comes on (as opposed to how long it is on each time).
On the charts I am seeing the gaps between on-times wider in the early hours then at mid afternoon for example. Makes total sense as the ambient temperature is greater so it has to work harder.

I am able to see a constant power usage of around 24W, and the fridge on makes it jump to around 57W for that 5 minute period.
Recap: The Fridge is rated at 84kW/annum, which equates to around 240Wh/Day (10Wh/Hr).
Generally I have been seeing numbers around that most of the time, but for a few hours today, the power consumption has been around 10Wh higher in those hours, which I will put down to the fridge working harder - reason being that I turned the fan off last night to allow the ambient temp to rise to stress the fridge more - and the ambient temperature peaked inside the van at 45C, so quite toasty! When I went in there at around 7pm to do some bits and pieces it was 35C, so probably been pretty warm in there all day!

At those temps I expect the fridge to be working harder, and instead of it kicking in around 5 or 6 times in 3 hours (between midnight and 3AM or 3AM to 6AM), it kicked in around 9 times between noon and 3PM and between 3PM and 6PM.
However in terms of performance, it is working pretty well how a fridge typically does - the interior temp has had a minimum of -1C and a max of 6C. This is about (or maybe actually better?) then I would expect - and certainly better than the Waeco CRX-50 I had before (I monitored the temps of that with the same IN-OUT LIDL Thermometer).

So Conclusion there is: Pretty well as expected. Target Consumption matches specs; consumption increases as ambient temp get significantly higher, but the consumption increase is not massively large and on a par with "proper" MH 12V fridges
(the SOC dropped to its lowest value of 96.2% at 08:30 but by 10:30 was back to 100% with the solar having kicked in and pumped 300Wh into the batteries in those two hours.

Might be worth mentioning that the Fridge is currently totally empty, and if working on same idea of adding ice blocks in a coolbox to make it work better, if the Fridge were half-full, the fluctation would probably be a bit less?


As a PS, as mentioned, temp was 35C when I went in at 7PM. Turned the Maxxair fan onto AUTO with a target temp of 22C - got there within 30 minutes and then fan turned itself off and lid shut, so very pleased with how that is working

 

[wildebus]

Well, looks like summer is over!

But in case it comes back, I fitted an external 12V Fan to the back of the Fridge and directed at the compressor

Extra Fan on Fridge Rear by David, on Flickr

Wired up to a Digital Thermocouple Controller - KKmoon 10A 12V Digital Temperature Controller Thermocouple -40℃ to 120℃ with Sensor Delay Protection Function: Amazon.co.uk: DIY & Tools

Which I installed in the under-cupboard plinth.

Cooler Display by David, on Flickr

not easy to see, but it is the kind of device that you don't really need to access on a regular basis as once set it runs automatically. Not sure yet what temp I need to set to have the fan come in.
I'll probably have to get a max/min thermometer on the back to find the range to get an idea and then repeat with the fan set to cut in and see what effect it has had. The rear of the CRX-50 in my last camper hit 50C on occasion and I was meaning to install a cooling fan there but never got round to it.
I am more concerned to keep the compressor temp cooler for product reliability and longevity more then energy efficiency, but if it saves power that would be a bonus.

 

[wildebus]

How a PV System Reacts to Power Demands

Maybe the title should be "How MY PV System Reacts to Power Demands" as other Solar Controllers may (and probably do) react differently.
But anyway, thought this post and data may be of interest to PV Anoraks like myself


So a main consistant use of power in my system is the Compressor Fridge (I would have said constant, but of course the compressor is not alway on).
This is what happens when the Compressor kicks on (we are interested in the info between 17:25 and 17:45)

VRM-PV & Fridge - DC System by David, on Flickr

So power demand jumps by around the 35W the compressor uses when on.

But hang on... Despite the increase in demand by 35W - and so a increase current draw of around 2.5A, the Battery Monitor is not showing any extra call on the battery during the compressor on time with either higher current OR a drop in voltage due to extra load

VRM-PV & Fridge - Battery V & C by David, on Flickr


How come? Well, the Solar Controller detects the increased demand from the system and instantly pulls in more power from the Panels

VRM-PV & Fridge - PV Yield by David, on Flickr

And the Solar Version of the Voltage and Current Chart show how that increased yield is converted into increased current provision to cover the fridges requirements

VRM-PV & Fridge - Solar BV & C by David, on Flickr


And all the while, the MPPT Controller remained in Float Mode

VRM-PV & Fridge - Solar MPPT State by David, on Flickr


As said, some of this action will vary for different controllers, especially between PWM and MPPT, but think it may be of interest.

 

[wildebus]

....
I look forward to seeing the results when the fridge is in practical use in higher ambient temperatures....

Be interesting to see the summer figures to get a direct comparison to a 12v fridge....

I'd suggest leaving more testing until the early to mid summer when conditions might be representative enough to provide useful information for those thinking of installing a mains fridge. Then of course the figures will need to be measured from the battery so as to include inverter losses.

The above are a selection of replies from around March, pointing out that usage info in the summer maybe of interest, which of course I agree with and always planned on doing when the summer arrived!


So Summer is here - and yesterday was maybe as hot as it usually gets in the UK. The outside temp in the shade went to 28C (82F) and the temp in the camper reached 44C (having windows all around and no shades up meant a toasty interior!). It was warm enough that a block candle I had on the counter top went soft and started to melt - so I think that is warm enough for a "summer test" now?

So down to business.
I have a min/max temperature gauge in the Fridge and that ranged from 1.1C to 5.6C - a healthy tight range fluctuation I think. So I think that confirms the fridge was in a healthy working condition throughout the day.
I saw a reading of up to 38C from the Temp probe on the compressor (this will be with the computer fan running). Quite high, but as the ambient temp inside the camper was getting so high (my Min/Max thermometer recorded upto 44.3C), blowing hot air is not going to have much effect - but what it does confirm is that the fridge was fine working in that kind of environment.

Now to the power figures. These charts are for the entire day yesterday - midnight to midnight - and show what power is being consumed - not just for the fridge, but in total. However, as per previous discussions and graphs, the fridge has a very distinctive tell-tale when it comes to power use, so it is very easy to spot Fridge Power and non-Fridge power


VRM-HotDay-PowerUse by David, on Flickr
As per previous notes, the spike seen on some parts of the graph occurs EVERY TIME the fridge compressor starts. It is however so short lived, the data sample that takes place every minute usually doesn't show it.
Each time there is a little blip on the graph (most obvious between midnight and 9AM but still can be seen pretty easily after that), that is the fridge kicking on.
What is surprising is that despite the high ambient temperatures, the frequency of compressor starts had very little change between night time and peak day (the internal van temp varied from a high of 44.3C to an overnight low of 14.6C). I would suppose (this is supposition) that if the fridge were actively in use (door opened and closed quite a few times) then the frequency would increase somewhat, but I have not seen much variation in the Compressor-On frequency compared to ambient temp in the months and months I have looked at the data.

Going back to the chart above, you see the power consumption rise at around 10AM-ish and more so from around 2PM and 5PM.
The first rise will be due to the MaxxAir fan kicking on automatically and later on with the doors being open (and courtesy lights with standard bulbs going on, powered by Leisure batteries now) and me whacking the fan up to 100% to try and cool down the interior more. The Fridge itself is actually lesser power consumer here.


So another question that comes up - is this only feasible for someone with a big battery bank and lots of solar?
Well, this is the SOC (State of Charge) for the entire day.

VRM-HotDay-SOC by David, on Flickr
The fact it was a very hot day has had NO real impact on the State of Charge pattern - back to 100% SOC by 10:30 and stayed that way until 6:30.
Power Usage Peaked at around 160W when the Fridge Compressor on (that is max of 5 times x 5 minutes in each 3 hour period) and the Peak otherwise was around 125W.
The Total power consumed midnight-midnight was 1460Wh - however, there are two things to bear in mind
1) The Solar brought in 1410Wh of energy - so a total deficit of 50Wh (around 4Ah on a DC system if you prefer that nomenclature) over a full day - so the battery bank could easily have been smaller.
2) The Solar system was actually in Float mode from before lunchtime until after 5pm and was only delivering specifically what the system required (the batteries were at 100% so no room for more power there)

VRM-HotDay-MPPT by David, on Flickr
So on a day like yesterday, the fact I had 400W of PV panels was not a factor as I was only harvesting something like 100W on average at the time of day when Solar would be at its peak performance.
A 100-200W System would have done the job just as well yesterday.


So conclusions?
A Domestic Fridge seems to work fine in a Campervan Environment.
Its power consumption is not noticabably impacted by high ambient temperatures.
The Power Consumption ties up very closely with the manufacturers energy statement (at least for MY fridge it does - I guess other models may vary) and is easily comparable to 'proper' Recreational Fridges.

The initial reason for selecting a Standard Household AC Fridge instead of a 12V Compressor Fridge was on a cost basis - £300 (inc Inverter) vs £700 odd.
The information I have gathered over the last 8 months or so has led me to believe that there are virtually no downsides to having an AC fridge in a Campervan, and the cost saving is tremendous!
And the flexibility .... If I were to go abroad on a extended tour and the Fridge failed, I could buy a replacement unit for around £200 at countless electrical shops. I would be looking at another £500 for a Weaco unit or as some people recently experienced on this forum, £1500 for a replacement 3-Way!!


Guess what kind of Fridge I would be fitting next time I build a Campervan?

 

[jagmanx]

Interesting

Certainly powerful (pun intended) data to support electric only.
Gas abroad only really works imo with a refillable system at say £600.
By eliminating gas £600 saved thus available for extra batteries and a good quality inverter or 2.
Extra solar panels.
Induction hob and microwave relatively cheap.
Fridge much cheaper.
Even an electric bbq or grill ok.
Also weight and space slight saving gas tanks gone but batteries needed.
Winter is the problem either ehu or genny needed.
As WE only use moho in summer it would work for us.......but the cost of changing is not worthwhile.

 

[Tony Lee]

We spent late autumn early winter in Iceland last year. Thank goodness for propane and hookups.

 

[hairydog]

So your conclusion is that in hot weather, the fridge uses 1460 watt hours of power in 24 hours.

That's useful information.

 

[wildebus]

So your conclusion is that in hot weather, the fridge uses 1460 watt hours of power in 24 hours.

That's useful information.

No, that is NOT my conclusion.
My ENTIRE Electrical system in my Campervan used 1460Wh of power in 24 Hours on the day in question.
That included a powerful roof fan running for most of the day, and often at full power, 3 X 5W filament lamps running for many hours, an internet router and booster running 24/7, a mobile phone on charge 24/7, a tablet charging most of the day and an Amazon Echo playing for a few hours.

The Fridge itself was a small proportion as you would clearly understand if you actually read my post unless you are just trying to cause trouble again?

 

[wildebus]

We spent late autumn early winter in Iceland last year. Thank goodness for propane and hookups.

Excellent point. I will bear your advice in mind not to rely on solar if holidaying in Winter in Iceland
Any more handy tips?