Additional solar system & B2B for compressor fridge

[wfdTamar]

This is where the fridge is now so you can see there is a definite limit on the size. Stupidly I didn't measure it before leaving, but I know the dimensions of the existing fridge. The stove is right on top of it too. Existing is 821x525x541mm (HxWxD) - 97 litres. Height and width are very fixed, no way to enlarge those. Actually could go for a slightly lower capacity fridge with no great loss. Maybe about 80-90 litres.

The 93 litre Inventor is listed at 860mm high with no removable top. I can't see that fitting unless it would with the feet off, but they're usually only on the front.

 

[wfdTamar]

Can you not fit a stand alone solar controller just for the extra panel and wire it directly to the LB

That's what I've done with the current solar setup. However, I'm talking about more than just an extra panel for a compressor fridge. It would need at least one, possibly two extra leisure batteries and extra panels just to allow for the fridge. That's where it gets complicated working with an EBL. I'd also be concerned about overloading the alternator. The AandN Caravan Services site talks about this on their 'add a second battery' page.

 

[Mark135]

That's what I've done with the current solar setup. However, I'm talking about more than just an extra panel for a compressor fridge. It would need at least one, possibly two extra leisure batteries and extra panels just to allow for the fridge. That's where it gets complicated working with an EBL. The AandN Caravan Services site talks about this on their 'add a second battery' page.

Maybe I'm not understanding how the EBL works, I thought this was just a combined mains, solar and b2b. If so, can't you just add additional LB's in parallel with the existing and add however many additional panels you need connected through their own separate solar controller directly to the LB's ?

 

[wfdTamar]

As they explain on that AandN page, any motorhome controller has limits. Mine is a 2002 model and is sized for one 90-100 Ah battery and a small solar array (with a 10A limit I think). Adding components without really thinking about extra loads is asking for trouble. Have a look at that site - I found it really good and well explained, but I think linking to it from here is verboten due to a difference of opinion between site owners (petty, I know).

 

[Mark135]

As they explain on that AandN page, any motorhome controller has limits. Mine is a 2002 model and is sized for one 90-100 Ah battery and a small solar array (with a 10A limit I think). Adding components without really thinking about extra loads is asking for trouble. Have a look at that site - I found it really good and well explained, but I think linking to it from here is verboten due to a difference of opinion between site owners (petty, I know).

OK, I just had a read the AandN article and realise that your charger may not be up to it.
All I can suggest, if you don't plan to change the EBL in any way is what I think you said to start with and install a separate set of panels, controller and batteries for the fridge completely independent from the rest. You could always carry a portable battery charger to use when on EHU or from a Genny (sorry, swear word).

 

[wfdTamar]

Yes, forgot to mention I have a Victron 30A 3 output mains charger I can use too. I am tending to lean toward as separate a system as I can manage which only leaves the alternator to worry about. Worst case I upgrade that too (what the hell, its only money).

 

[wfdTamar]

Wildebus - did you try running your fridge from a 375VA Phoenix inverter, or are you just guessing it won't run it, or allowing a safety margin? The peak your fridge drew was around 5-600 watts. The peak for the 12/500 is 900, for the 12/375 is 700, so I wonder if it would do it. It's only that high for a very short time.

Ah, for anyone else, he's already covered that. According to his Victron info, peak was more like 90 amps. That doesn't show in the video on his fridge thread. He did try the smaller model inverters and they didn't work.

Selecting the right inverter for an AC Fridge

I know ... another thread about AC Fridges in Campers, but I thought it may be worthwhile to just clarify what to look for in an Inverter if you want to run an Mains AC Fridge in your Motorhome or Campervan. These are my tips on Inverter Selection for a Fridge. 1. What power rating is needed...

www.motorhomebuilder.com

 

[wildebus]

Wildebus - did you try running your fridge from a 375VA Phoenix inverter, or are you just guessing it won't run it, or allowing a safety margin? The peak your fridge drew was around 5-600 watts. The peak for the 12/500 is 900, for the 12/375 is 700, so I wonder if it would do it. It's only that high for a very short time.

The fridge failed to start with the 375VA Inverter just as it failed with the 250VA Inverter.
I was able to get more accurate info on peak current draw as my equipment changed and I saw the peak was greater than 600W. I have more information on this blog post - https://www.wildebus.com/blog/products/selecting-the-right-inverter-for-an-ac-fridge/
I'll post a key graph here to show the load that is possible

EnergySnapshot - V&C (noted) by David, on Flickr
Note that the 12/800VA unit still overloads everytime the fridge starts, so if an 800VA Inverter overloads, then a 375VA with a similar peak ability similar to the normal running ability would be hard pushed to be suitable.
See the graph below for a 800VA Multiplus

MP800-FridgeACvsOverload by David, on Flickr
Now bear in mind a characteristic of the way the data is sampled means that the peaks are not always captured (the data is sampled just once a minute; the peaks only last 1-2 seconds), but the overload situation is noted every time on an inverter that can run at upto 650W continuously.

Is the fact the inverter goes into Overload an issue? not if it is designed that way. From Victron ...
“Full bursts – High Peak output
Some electronic devices – particularly those which have an electric motor – require short burst of energy on start-up which is much higher than their rated power consumption. No problem – the Phoenix inverter has industry-leading peak-power capability.”
That peak-power capability is delivered in an 'overload' condition.

If you were to get the 98L Fridge that has the 131kW/Annum use, it is possible that it has a bigger compressor to cope with the freezer box (I don't know for sure). If that is the case, then I would not be surprised if the 12/500VA Inverter is not big enough either and you should get the 12/800VA unit as a minimum.
You can of course use a non-Victron inverter and go to 1000W for less cost than the Victron 12/500 or even the 12/375 which is too small anyway. there is no reason why you cannot. I selected and recommend the Victron for a number of reasons. Price is clearly not one of those, but I still would not get a non-Victron unit.

 

[wfdTamar]

Have you ever tried an inverter that has a normal load rating big enough to handle the fridge peak load to see if it doesn't make the 'overload hum'? A 12/1200, getting expensive - £327 over here, and heavy at 8kg!

 

[SquirrellCook]

Just on of interest, I fired up my mains fridge this morning. No ice box, more fridge space. Running from 2 Trojan T105's through a Victron 800watt inverter. 68watts being consumed. It also has a couple computer fans mounted to the radiator that only work when the fridge compressor is running.

 

[wildebus]

Have you ever tried an inverter that has a normal load rating big enough to handle the fridge peak load to see if it doesn't make the 'overload hum'? A 12/1200, getting expensive - £327 over here, and heavy at 8kg!

Simple answer. Yes. Obviously if the normal rating is above the surge, it is just 'another day in the office' for the inverter.
Right now I am using a 3000VA (actually a 12/3000/120 Multiplus) to run the fridge. It is actually less efficient than the smaller ones (but more efficient cost wise than having a 3000VA inverter AND another just for the fridge)

 

[wildebus]

Just on of interest, I fired up my mains fridge this morning. No ice box, more fridge space. Running from 2 Trojan T105's through a Victron 800watt inverter. 68watts being consumed. It also has a couple computer fans mounted to the radiator that only work when the fridge compressor is running.

68W sounds a lot if it is the inventor 45L fridge I think you have? I am not - and never have been - close to that on mine.

 

[wildebus]

To get a picture of how much extra load that an inverter adds when running a fridge, I am pasting a graph below

The Top graph is the AC power that the inverter is providing
The Bottom graph is the total load on the battery.
The start of each peak is the in-rush dying off.

Now bearing in mind, I have a pretty constant DC load (USB sockets, MiFi, etc) of at least 13W, so that needs to be taken from the Battery Power number of 69W to get what the Inverter is pulling i.e. 56W.
So for MY Setup of MY Fridge and MY Inverter, there is an inverter overhead of around 18W, when (and ONLY when) the fridge is running.
Also, it is correct to say that the bigger the inverter, the bigger the percentage overhead at the smaller load levels (think of it like a car engine - a V8 sat at the traffic lights will be using more petrol than a 1000cc hatchback engine), and the inverter I am using ( a 3000VA) is way bigger than the requirements the fridge has. If I was using the 12/500VA Inverter or the 12/800 Multiplus still, that Overhead would be significantly smaller (which is why it is important to size the Inverter for the requirements you have - just like engines in cars, bigger is NOT necessarily better when it comes to inverters).

 

[SquirrellCook]

68W sounds a lot if it is the inventor 45L fridge I think you have? I am not - and never have been - close to that on mine.

I'll switch out bits and bobs tonight to see what's pulling what. There may have been 5 watts running an extractor fan. The fridge is a Beko UL584APS class SN/T 130 litres A+ I know the extra cooling fans added a bit of loading, but the "On time" is reduced when it's hot.

 

[nabsim]

I have a different EBL to you (101-2) but had similar problems regarding solar going through the EBL and charging extra battery’s. I have 300w solar on the roof and go through a Votronic 250 Duo controller ( yes I know I have more panel but unlikely to every get 300w) directly to the battery bank. The mains charger in my EBL is 18amp and on advice from Martin at A and N I bought and fitted an additional Schaudt charger which was plug and play for me. At the normal 10x charger output I am good for 360ah battery bank, I had 270ah leisure bank which left some for starter battery.

I never thought the split charger system worked very well in my van so I got a Votronic 30amp B2B. It is very easy to fit with the EBL piggybacking on the existing firing fir all except the direct battery connections, it utilises some wiring but doesn’t go through the EBL. The B2B I got is not the ones in aluminium case but look similar to the mppt duo controller and similar size.

The only downside of not going through the EBL really is it doesn’t show on the control panel. My DT101 display doesn’t not have solar display anyway so no loss for me. It shows the voltage of battery just not where it’s getting it from apart from mains or not.

if you can’t (or don’t want to) get additional Schaudt chargers to suit your battery bank I would rig so you can charge your battery’s from mains before connecting hookup if necessary. I don’t know enough about electrics to know if you can disconnect mains charging through the EBL and still get other controller functions.

I have a Waeco 110ltr fridge freezer and diesel heating, fridge never had the 240v module so is purely 12v.

 

[SquirrellCook]

I'll switch out bits and bobs tonight to see what's pulling what. There may have been 5 watts running an extractor fan. The fridge is a Beko UL584APS class SN/T 130 litres A+ I know the extra cooling fans added a bit of loading, but the "On time" is reduced when it's hot.

Looks like it was happier with a cold start. After isolating as much as I come it looks like the fridge consumes with it’s fans 58-60 watts. The inverter about 9 watts. There are a few other bits that take a little. Watching the BMV as the fridge started I saw 4 figures, so a 1k plus spike.

 

[wildebus]

This is where the fridge is now so you can see there is a definite limit on the size. Stupidly I didn't measure it before leaving, but I know the dimensions of the existing fridge. The stove is right on top of it too. Existing is 821x525x541mm (HxWxD) - 97 litres. Height and width are very fixed, no way to enlarge those. Actually could go for a slightly lower capacity fridge with no great loss. Maybe about 80-90 litres.

The 93 litre Inventor is listed at 860mm high with no removable top. I can't see that fitting unless it would with the feet off, but they're usually only on the front.

Just went out to measure the fridge.... I make the fitted height 845mm which gives clearance of maybe just 5mm between the floor and the bottom of the door - so at the very very least you would need at least 840mm to allow the door to open (on the 93L, the top cover does not go over the fridge door and the body of the fridge is the same height as the door top to bottom).

So looks like if you are stuck at 821 maximim, the 93L like I have is no use to you.
I think Inventor list a 68L (IIRC?) but it is an A+, not a A++, so will use more power, but I would assume that much smaller would mean shorter so would fit?

 

[wfdTamar]

Even the Inventor 98L might not fit as its 86.5 cm. The top comes off, but I don't think that gives much extra as there's stuff up under the lid. Its A++ too though which is odd as it does, as you say, use about 50% more power than the 93. I reckon they work out the rating based on what functions it has as well as volume and the freezer seems a bit more serious on the 98. Its quieter too at 39 vs 42 db. I don't think the 68L would be big enough. I saw another brand about 80-85 which I could see being an ok size.

nabsim - yes, your setup is very close to mine as I have it now and the extra bits are what I've just bought. Cheaper to buy them from the UK ex VAT, then bring them over with me (10 % off too). Are you running a compressor fridge?

Have:
- 200 watts solar
- Votronic Duo digital 250 (with the display and temp lead). You get more info from these than the vans display.

Got coming:
- Votronic Duo Digital 430 (with another display and temp lead) - overkilll for another 200 watts solar, but means I can plug in additional portable panels if desperate. Gotta find out if there's such a thing as an exterior 'solar plug in under a flap' kinda thing. Or I could just run it into a locker (yes, that'd be better). This will be for the 'fridge only' leisure system. Separate from the original system.
- Votronic B2B 30A (same as yours) (with display).

I'll use my Victron Phoenix 12/500 inverter (and hope it works with whatever fridge I get). Just need to get the solar panels, battery(s) and all the fittings & wiring stuff when I'm back in the UK, then hope I can actually find a fridge that fits. Otherwise I'll have to get an expensive 12 volt fridge, which defeats the purpose.

I'll also be able to use my Victron 30A 3 outlet mains charger to charge at least the one (or two) fridge batteries, if not all leisure batteries.

Spend the whole holiday wiring it all up, then have a £1200 ice cream. Bluddy motorhomes, just one step short of a boat as a money pit.

 

[wildebus]

Noise wise, I don't know the actual noise my 93L makes versus the quoted noise but I would regard it as silent. I usually have to open the door to look at the light to see if it is running or not (the way the inverter is setup the light only stays on when the fridge compressor is running).
Another chap on the forum says it is the quietest fridge he has ever had anywhere and I would say the same (these really are super units!)

 

[wfdTamar]

Might be the inverter is more of an issue for noise, but that can go in a cupboard or under the couch (sofa) which will help. I sleep in the drop down bed over the cab and the fridge is up the other end. I’d insulate around the front perimeter too.