AC Fridge In Campervan -.Power Consumption Test

wildebus

Full Member
I would expect a 12/1200 would be ok :)
My Fridge is a right devil, so the Peak wattage I saw when I had a meter directly on the inverter was 666W :devilish:

The video above also captures the "buzz" when the Fridge starts and the inverter overloads.
 

Duckato

Full Member
I wonder if the compressors do loosen up, amazingly even on eco it has not stalled anything like as much as it was initially whilst connected to my small Victron and even under my carport the solar panels are replenishing the batteries every day.

So far so good other than than damn buzz!
 

wildebus

Full Member
I wonder if the compressors do loosen up, amazingly even on eco it has not stalled anything like as much as it was initially whilst connected to my small Victron and even under my carport the solar panels are replenishing the batteries every day.

So far so good other than than damn buzz!
I reckon initially they are 'tighter'. I don't know if it is the same kind of thing but in the olden days (circa late 1980's) the first miniaturised computer hard drives (talking 5.25" and 3.5") used to suffer from stiction and needed a jolt to get spinning from stationary and they tended to be ok later on (We used to build the small 20MB jobbies Alan Sugar used in the Amstrad 1640 PCs)

I used to have my 12/500 Inverter in the electrics area that was under the bed (not in a compartment, but just under the mattress) and it did do the jolt/buzz each time the fridge started but I didn't really notice it and it didn't wake me up (or stop me getting to sleep). However the Weaco CRX-50 12V Compressor Fridge in another camper I had I used to notice much more when that kicked on with the little shake the fridge did.
One difference was the 12V fridge was bolted to the cupboard that was bolted to the low base cupboards that made the bed base - so there was a direct physical transmission route, whereas in my current camper with the 240V fridge the bed and inverter have no direct connection. Would damping the inverter mount make a difference to how much you noticed it maybe?

I'm currently working out a setup for a small camper using the 45L Inventer Fridge and trying to decide whether to go for the 800VA or 1200VA version within the Multiplus range. 1200VA would eliminate the buzz for sure but is an extra £200 (that extra does include a more powerful mains charger though)
 

Duckato

Full Member
Ah mains chargers bring something else the equation my Ambulance came with 2 Votronic 30A duo chargers (yep it originally had five batteries and four different 12v systems) these on face value are brilliant, highly configurable, rugged etc designed for permanent use everyday etc but....

They are dreadfully inefficient, when not actually charging anything they draw about 25 to 30w constantly I have kept one of them for use on mains hookup when away but at home I use my Ctek instead which only draws 3w at idle.
 

wildebus

Full Member
Ah mains chargers bring something else the equation my Ambulance came with 2 Votronic 30A duo chargers (yep it originally had five batteries and four different 12v systems) these on face value are brilliant, highly configurable, rugged etc designed for permanent use everyday etc but....

They are dreadfully inefficient, when not actually charging anything they draw about 25 to 30w constantly I have kept one of them for use on mains hookup when away but at home I use my Ctek instead which only draws 3w at idle.
I guess to a degree that inefficiency does not matter too much when the cost per kW is what 15p or so? I wonder if you might actually be better off with the CTEK when away on site hookup in case you have to pay OTT rates per kilowatt?
 

wildebus

Full Member
I noticed in this hot weather the fridge was running for much longer - i.e. the On-Off Duty cycle that is typically around 10 minutes on, 60 minutes off had become many hours on! The Fridge was still working as expected (ice cubes and lollys in the ice box still frozen :) )

When I had a check yesterday, I noticed that the temp setting had been knocked and moved to the "Max" (this is the only annoyance I have with the Inventor Fridge - the dial is much too easy to get moved when getting stuff in and out :( ). This will be part of the reason for the longer running.

However, I thought it might be interesting to log the Fridge Temperature to the times the Fridge kicks on to see the pattern. I can easily tell when the Fridge starts as it wakes up the Inverter (it is the only thing that will do so when the Camper is unattended if I don't have the Hot Water Heater set) so it will be an easy comparision.

So I reset the Temp Dial to the usual position I use and fitted a Temperature Sensor inside the Fridge. I also fitted a Temperature Sensor to record the ambient temperature inside the camper to see if that will tell me how fast the fridge warms up when the Compressor is not running.

This is the Inverter ON (so Fridge ON) pattern mapped on the Internal Fridge Temperature ....

Fridge-Inverter
by David, on Flickr
You can see how the Fridge kicks on at some time after the fridge reaches 2C, and then goes off again once the fridge drops to 0C? The length of time once it hits 2C seems to vary a bit but I think (going by the data sample here) that it is when the fridge hits 1C, some kind of timer starts up, as everytime the fridge compressor kicks in 27 minutes after the fridge temp went from 0C to 1C, and then stops 3 minutes after the temp has dropped back down to 0C.

It is a bit premature to be definate about this - and of course other fridges will vary in their behaviour - so will be monitoring further. I plan to defrost the fridge in the next couple of days (the "max" setting has frosted up the ice box a little) and will monitor the power pattern as it runs to get down to temp, but reckon it is useful to know and predict when the compressor with start and stop :D
 

wildebus

Full Member
Sounds like its time to fit a locking screw of some sort to the thermostat knob ? :)
need something :) I removed all the contents for the defrost and the three bottles of water under the ice box were frozen solid.
On the plus side, it shows the fridge can work in pretty extreme temperatures :D
 

SquirrellCook

Full Member
We don't use a fridge with an ice box, for the amount of time we are away from shops the extra space is better for us. Mind you, I do get told of if I've got it too cold and start to freeze things. Since fitting cooling fans in the fridge cooling vent our on times do seem shorter.

Mark
 

wildebus

Full Member
We don't use a fridge with an ice box, for the amount of time we are away from shops the extra space is better for us. Mind you, I do get told of if I've got it too cold and start to freeze things. Since fitting cooling fans in the fridge cooling vent our on times do seem shorter.

Mark
I love having a small icebox in the fridge :) Out on a day trip on Friday (bit of Tomahawk throwing, pistol shooting and archery) and went back to the camper for a late lunch and filled the glasses with ice cubes for some chilled cider :love: :p (y)


Since moving the dial back to the right place, I am back to the more regular on-off cycle (but the weather has cooled as well a little) and the temperature now goes between 1C and 2C.
Took about a hour to get down to setting following defrost, then I slightly tweaked the dial position to drop the average temp 1C to my target preference.
I didn't actually realise just how stable the fridge internal temp was! Fluctuating within a degree is remarkable for a basic domestic product I reckon. Impressed even further with this fridge!
1564308343444.png




(I have also now put a bit of tape on the dial so it cannot be moved from the setting accidentally)
 

Duckato

Full Member
I have noticed similar to your post above that the on off cycles are fairly consistent but with the crazy heat we have had this week mine did speed up noticeably and yes I have temp probe and it does keep a very consistent temp, the side of my fridge gets quite warm so I am glad I have left some ventilation all round.


Picking up from what I mentioned a while ago, when my charger is plugged in it completely smoothes out the on off waveform of the voltage dips that I see when the fridge is running only on batteries!

I find that a bit baffling, its a 30A charger running over comparatively lightweight cabling and its mounted quite a way from the batteries it does have a voltage sense wire but I can't imagine the charger could react that quickly to a voltage change or could it!

I turned the charger on at 11:30 today so you can see prior to that the transients then once on bulk then float and hardly any sign of the transients from the fridge

IMG_0044.PNG
 

wildebus

Full Member
It will be interesting to see how the Victron 12/1200 behaves on the next build.
I had the "buzz" on the 12/500 Phoenix Inverter.
The 12/800/35 Multiplus device gave an 'overload' warning each time the fridge came on due to the in-rush but I can't remember if anything physical was noticed - it was only used for a short time as a test unit really.
So in the next day or two I will be doing another test which is combining the two styles of unit - namely a Victron Multiplus 12/500/20 which is arriving today and which I want to configure and test before sending it on to the customer - and running a Compressor Fridge will be a good test for the unit and also be interesting how it reacts to the overload (warning report only or something more physical/audible?). I am expecting a similar result to the 12/500 Inverter but maybe the different overall design has changed this?
 

SquirrellCook

Full Member
I am seriously impressed with the functionality of the multiplus on paper, but it's that eggs thing. At least with stand alone devices you may be able to mix and match in the event of trouble. That said, for those that are unable or willing to fiddle with stuff it might be a better answer to have only one part to swap out.

As you've actually played with one Dave, I notice there is a 1amp supply to hold the engine battery up. Is that adjustable between 12 and 24volts? For example I have 12 volt habitation and 24 volts in the base vehicle.
 

wildebus

Full Member
I am seriously impressed with the functionality of the multiplus on paper, but it's that eggs thing. At least with stand alone devices you may be able to mix and match in the event of trouble. That said, for those that are unable or willing to fiddle with stuff it might be a better answer to have only one part to swap out.
I get where you are coming from here and I do agree generally.
The Multiplus is a bit different though. Having the functionality of a AC-DC Charger and a DC-AC Inverter in the same unit means you get benefits over and above having simplified cables and space saving (which is often the main benefits of having combo units). Those extra benefits come at a price though - the Multiplus is more expensive then getting the equivalent individual Charger and Inverter devices. But I think it is worth it :)

As you've actually played with one Dave, I notice there is a 1amp supply to hold the engine battery up. Is that adjustable between 12 and 24volts? For example I have 12 volt habitation and 24 volts in the base vehicle.
Good question and I actually double-checked this the other day :) The answer is no :( According to the manual the main DC charging output is configurable to a few options, such as 14.1V, 14.4V (or their 24V equivalents) and the 1A trickle charge for the starter which is at "a slightly lower voltage" (I am guessing the 'slightly lower voltage' is based on the starter battery assumed to be a Wet Cell Battery so usually wanting less)


As an aside - but an important aside - if you were able to use the trickle charge output and had a B2B charger that autostarted based on starter battery voltage like most do nowadays, what would happen is that the starter battery would eventually rise to the level that would switch on the B2B and that would then actually pull power from the starter battery itself to transfer to the Leisure Battery. This lowers the starter battery voltage so the B2B probably goes off again until the battery again rose to the switch on level and then B2B goes on again, and this would repeat itself over and over so the end result is the Starter Battery would actually get depleted more than charged with the trickle charger UNLESS you have an ignition/D+ controlled B2B
Sounds a bit weird but it is due to the way most (all?) B2Bs work and their algorithm for detecting voltage.
So the Trickle Charge is less use then you might think. My own Multiplus has a 4A Starter Battery connection but I have not connected it for this reason.
 

SquirrellCook

Full Member
Ok then Dave, thinking aloud about a Multiplus 12/800/35

35amp battery charger, I guess it's AC demand would be around 0.5kW? So my noisy silent inverter generators 900Watt output should be enough?

700Watts of inverter output you mention was unhappy starting your fridge. Does the overload warning require any user intervention?

I guess if I really wanted too, I could use the 1 amp output through a DC DC converter to get it up around 28 volts at 400 or so milliamps. (would it be worth it) Bigger mercs suffer from constant battery drain that I've never been able to find all the loads.

How much other kit is required to use it? The cost of stand along devices is only around £50 is using the VE stuff.
Connectivity, I assume it's not Bluetooth? Can you play around with the settings as you can with other Victron stuff if connecting with a Dongle?

The engine start batteries will be charged with a couple of Victron 12/15 chargers, I have one and I like how it works.
These batteries also run the internal lighting and will have a 1200 watt inverter connected to them also.
This effectively doubling up allows some redundancy if I have problems.
Each system can run each other if needed.
 

wildebus

Full Member
Ok then Dave, thinking aloud about a Multiplus 12/800/35

35amp battery charger, I guess it's AC demand would be around 0.5kW? So my noisy silent inverter generators 900Watt output should be enough?

700Watts of inverter output you mention was unhappy starting your fridge. Does the overload warning require any user intervention?

I guess if I really wanted too, I could use the 1 amp output through a DC DC converter to get it up around 28 volts at 400 or so milliamps. (would it be worth it) Bigger mercs suffer from constant battery drain that I've never been able to find all the loads.

How much other kit is required to use it? The cost of stand along devices is only around £50 is using the VE stuff.
Connectivity, I assume it's not Bluetooth? Can you play around with the settings as you can with other Victron stuff if connecting with a Dongle?

The engine start batteries will be charged with a couple of Victron 12/15 chargers, I have one and I like how it works.
These batteries also run the internal lighting and will have a 1200 watt inverter connected to them also.
This effectively doubling up allows some redundancy if I have problems.
Each system can run each other if needed.
around 500W is around right if the charger is at full pelt. You could use that generator to provide all the neccessary power for battery charging.

Now the Inverter load ... the Victron 500 is a 430W Inverter. the 800 is a 700W Inverter - so neither are enough to provide the inrush current on a continuous basis - but of course, that inrush is less than 2 seconds - and the 500 can provide 900W for 30 seconds, and the 700 can provide 1600W for 30 seconds (see https://www.victronenergy.com/upload/documents/Datasheet-MultiPlus-500VA-1600VA-EN.pdf).
so the Overload Warning is just that - a warning, and not a fault, and clears itself once the overload is no longer present and no user interaction is required.

using the 1A secondary output through a DC-DC converter? you could do that but as you say, is that level of charge worth it? I suppose it might slow down the drain?

You can use it stand-alone with the switch mounted on the device to go on/charger only/off; you can fit a remote 3-way switch to do the same thing (couple of quid); or go further and get a USB dongle to connect to a Computer or a Bluetooth Dongle to use via the Phone, same as other Victron kit - looking at around £80 for those options.
This is a screenshot of Victron Connect talking to the Multiplus this afternoon (I'm supplying the 12/500/20 with the Bluetooth Dongle)
1565805111193.png

The VE Bus Kit (the more advanced Victron kit) tend to have just the basics configurable via Bluetooth and the major items via the VE.Configure program which must be done using a PC and either via the USB Dongle or via the Venus OS system. Once it is setup though you don't really change anything, just turn things on and off really.
 

wildebus

Full Member
I had the "buzz" on the 12/500 Phoenix Inverter.
The 12/800/35 Multiplus device gave an 'overload' warning each time the fridge came on due to the in-rush but I can't remember if anything physical was noticed - it was only used for a short time as a test unit really.
So in the next day or two I will be doing another test which is combining the two styles of unit - namely a Victron Multiplus 12/500/20 which is arriving today and which I want to configure and test before sending it on to the customer - and running a Compressor Fridge will be a good test for the unit and also be interesting how it reacts to the overload (warning report only or something more physical/audible?). I am expecting a similar result to the 12/500 Inverter but maybe the different overall design has changed this?
I tried the Multiplus 500 and it did the same thing as the Phoenix 500 Inverter - Buzz on load, overload light came on for a second and then went off and fridge running nicely.

Of the small Multiplus units, I'd recommend the 12/800 over the 12/500 as it is only £100 more expensive but as well as getting a more powerful inverter you get a 35A Mains Charger instead of a 20A (a nice difference if you have a bigger battery bank) AND you get the Power Assist feature which can be handy if on a limited amperage hookup.
The 12/1200 is quite a big jump in price with another £200 extra but of course is more powerful again so depends on your needs.
In terms of Inverter outputs, the power demand of a fridge is really just noise, so if you had need for say a 1000W inverter, the Multiplus 12/1200 would do the job perfectly along with the other things it offers, and should the Fridge start up when you are using the inverter with a 1000W draw, that 900W Inrush spike wouldn't matter and would be supplied alongside the existing 1000W (so the 1000W inverter will deliver the 1900W without an issue except for an informational overload warning). I rationalised my multiple inverters to a Multiplus 12/3000/120 so I can run my Induction Hob or electric Water Heater and if the fridge comes on while in use it doesn't matter and when the inverter is not having to provide a load it uses around 2Wh/Hr (while it is ready to come on automatically on demand). Plus of course a mege 120A battery charger which is a nice to have for a big battery bank :)
 

SquirrellCook

Full Member
Multiplus features?
Am I reading this correctly Dave?
2.3 Self consumption – solar energy storage systems When the Multi is used in a configuration in which it will feed back energy to the grid it is required to enable grid code compliance by selecting the grid code country setting with the VEConfigure tool. Once set, a password will be required to disable grid code compliance or change grid code related parameters.
If the local grid code is not supported by the Multi an external certified interface device should be used to connect the Multi to the grid.

Does this mean whilst I'm parked up at work, or home and connect to my building mains supply. I can use the normally wasted solar absorption of my Motorhomes solar array to offset my consumption of grid supplied power?

Now that would be a handy feature if it was so.
 

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