Fridge/Freezer – and the Battery.

[Solomongrundy]

We rarely use EHU when on holiday and when the Motorhome is parked up overnight, say from 5pm until 9am, we have the Fridge/Freezer running on the Gas setting.

Does it use a small amount of power from the leisure battery or could it quickly drain the battery despite being on the gas setting?

I realise that how full the fridge/freezer is and the outside temperature affect the performance but I'm not looking for a definitive figure only a general idea of the power likely to be taken from the battery.

I have a Dometic RMD 8505 Fridge/Freezer.

[Guest Had Enough]

Well, I'm the least technical person on here but my experience would be that on gas the fridge uses no electricity whatsoever.

 

Until of course you open the door and the light comes on, when you'll be using a minuscule and barely measurable amount.

[Robinhood]

...running on gas, it will take a (very) small amount of current to power the AES and other controls (and the light when the door is opened).

 

This is via a permanent 12V supply (the recommended protection for which is a 2A fuse - rather an over-provision). The much heavier demand 12V supply to the cooling (actually heating) circuit is separate, and should only function when the engine is running.

 

I wouldn't worry too much about the consumption for anything but a very extended stop.

[Guest Had Enough]

Robinhood - 2014-11-06 11:09 AM

 

...running on gas, it will take a (very) small amount of current to power the AES and other controls (and the light when the door is opened).

 

This is via a permanent 12V supply (the recommended protection for which is a 2A fuse - rather an over-provision). The much heavier demand 12V supply to the cooling (actually heating) circuit is separate, and should only function when the engine is running.

 

I wouldn't worry too much about the consumption for anything but a very extended stop.

 

Well, I've learned something else from my membership of this forum. If I knew what an AES is my education would be complete. ;-)

[Robinhood]

Had Enough - 2014-11-06 11:28 AM

 

 

Well, I've learned something else from my membership of this forum. If I knew what an AES is my education would be complete. ;-)

 

Automatic Energy Selector (the 8xx5 series, amongst others, has this feature).

 

I suspect the fridge in your new juggernaut may be thus fitted.

 

;-)

[Guest Joe90]

Had Enough - 2014-11-06 11:28 AM

 

Robinhood - 2014-11-06 11:09 AM

 

...running on gas, it will take a (very) small amount of current to power the AES and other controls (and the light when the door is opened).

 

This is via a permanent 12V supply (the recommended protection for which is a 2A fuse - rather an over-provision). The much heavier demand 12V supply to the cooling (actually heating) circuit is separate, and should only function when the engine is running.

 

I wouldn't worry too much about the consumption for anything but a very extended stop.

 

Well, I've learned something else from my membership of this forum. If I knew what an AES is my education would be complete. ;-)

 

Automatic Energy Selection. ;-)

 

Or how to make something overly more complicated than was previously the case.

[Guest Had Enough]

Robinhood - 2014-11-06 11:33 AM

 

Had Enough - 2014-11-06 11:28 AM

 

 

Well, I've learned something else from my membership of this forum. If I knew what an AES is my education would be complete. ;-)

 

Automatic Energy Selector (the 8xx5 series, amongst others, has this feature).

 

I suspect the fridge in your new juggernaut may be thus fitted.

 

;-)

 

Thank you o wise one. And stop with the juggernaut already! (lol)

[Robinhood]

Had Enough - 2014-11-06 11:40 AM

 

Robinhood - 2014-11-06 11:33 AM

 

Had Enough - 2014-11-06 11:28 AM

 

 

Well, I've learned something else from my membership of this forum. If I knew what an AES is my education would be complete. ;-)

 

Automatic Energy Selector (the 8xx5 series, amongst others, has this feature).

 

I suspect the fridge in your new juggernaut may be thus fitted.

 

;-)

 

Thank you o wise one. And stop with the juggernaut already! (lol)

 

....I thought that, by definition, you can't stop a Juggernaut!

 

;-)

[Guest Joe90]

When operating in the AES mode, the AES mode indicator lamp (A) will illuminate. In this mode the

control system will automatically select the energy source with AC having top priority, DC second priority

and GAS third priority. If the control system has selected a particular energy source such as AC, and then

it becomes unavailable, it will automatically seek out the next available energy source. ;-)

 

Unless it goes wrong, then you are in for a minimum £200 bill plus fitting :-S

[lennyhb]

Dometic specs quotes the electrical consumption as 3.2 a/h over a 24 hour period that's an average current draw of 133ma.

 

Worth noting a lot of the manufacturers now wire the AES fridges so that when in AES mode if there is no gas or mains present the fridge switches to the habitation battery. These 160 Lt fridges draw about 14 amps on when running on 12v so will soon flatten your leisure battery.

I pulled the fuse on my Elektroblock that gives the feed from the leisure battery to the fridge so it now works like they used to on 12v, only with the engine running.

 

 

[Brian Kirby]

lennyhb - 2014-11-06 11:59 AM

 

Dometic specs quotes the electrical consumption as 3.2 a/h over a 24 hour period that's an average current draw of 133ma.

 

Worth noting a lot of the manufacturers now wire the AES fridges so that when in AES mode if there is no gas or mains present the fridge switches to the habitation battery. These 160 Lt fridges draw about 14 amps on when running on 12v so will soon flatten your leisure battery.

I pulled the fuse on my Elektroblock that gives the feed from the leisure battery to the fridge so it now works like they used to on 12v, only with the engine running.

Seems even between different models/years from the same manufacturer there is not consistency. Our 2013 Exsis-i has a Thetford AES fridge-freezer. If the engine is stopped and there is no gas or mains available, it simply goes into "panic" mode after a few minutes, and sits with the fascia flashing. The only remedy is to turn off the fridge until the engine is re-started, and then turn back on. I had thought it would automatically re-start when the engine re-started but no, it has recorded a fault and the only re-set is to turn off and on at the panel. Never simple, are they? :-D

[lennyhb]

Brian Kirby - 2014-11-06 5:05 PM

 

lennyhb - 2014-11-06 11:59 AM

 

Dometic specs quotes the electrical consumption as 3.2 a/h over a 24 hour period that's an average current draw of 133ma.

 

Worth noting a lot of the manufacturers now wire the AES fridges so that when in AES mode if there is no gas or mains present the fridge switches to the habitation battery. These 160 Lt fridges draw about 14 amps on when running on 12v so will soon flatten your leisure battery.

I pulled the fuse on my Elektroblock that gives the feed from the leisure battery to the fridge so it now works like they used to on 12v, only with the engine running.

Seems even between different models/years from the same manufacturer there is not consistency. Our 2013 Exsis-i has a Thetford AES fridge-freezer. If the engine is stopped and there is no gas or mains available, it simply goes into "panic" mode after a few minutes, and sits with the fascia flashing. The only remedy is to turn off the fridge until the engine is re-started, and then turn back on. I had thought it would automatically re-start when the engine re-started but no, it has recorded a fault and the only re-set is to turn off and on at the panel. Never simple, are they? :-D

 

Since about 2007 Hymer have been wiring Dometic AES fridges as I described. One in our last van was a 7 series so no problem with fuse removed, current van with an 8 series with all this overkill electronic control, with fuse removed if no gas the alarm drives you nuts, but as we have the Truma Duo it always has gas unless we have turned it off for the ferry.

 

Why Hymer wire the Thetford one way and the Dometic another is a mystery as both manufacturers installation instructions are similar. As it does not appear to be a fridge function the switching to allow it to work must be in the Elektroblock both our vans have the same unit an EBL29.

My mates Carthago with an Dometic fridge & CBE electrics is wired the same as mine, ie fridge will run off the leisure battery if no other source of power.

[Solomongrundy]

Thanks for the replies.

To sum up, if I've got this right, there's minimal usage of the battery when the fridge/freezer is running on gas and if I turn off the AES then it can't switch itself to the battery if the gas ran out.

The AES works well at the moment but as you point out it will cost a bomb to repair or replace if it does go wrong.

I have another question about the heating system but I'll start a new thread for that.

Again, thanks

[lennyhb]

Brian, when I added the drawing the tex got lost:-

 

The 3rd fuse from the left controls it, marked Kompr./AES.

Is that fuse fitted in your van Brian?

[Derek Uzzell]

Had Enough - 2014-11-06 11:28 AM

 

Robinhood - 2014-11-06 11:09 AM

 

...running on gas, it will take a (very) small amount of current to power the AES and other controls (and the light when the door is opened).

 

This is via a permanent 12V supply (the recommended protection for which is a 2A fuse - rather an over-provision). The much heavier demand 12V supply to the cooling (actually heating) circuit is separate, and should only function when the engine is running.

 

I wouldn't worry too much about the consumption for anything but a very extended stop.

 

Well, I've learned something else from my membership of this forum. If I knew what an AES is my education would be complete. ;-)

 

Strictly speaking, the acronym “AES” (Automatic Energy Selection) only applies to Dometic products, with the alternative Dometic system being “MES” (Manual Energy Selection).

 

http://www.dometicapproved.co.uk/page.aspx?p=3way

 

Thetford fridge terminology is a mite more complex with “SES”, “MEC” and “EEC” being used.

 

http://www.swift-owners-club.com/support/oem-handbooks/thetford/troubleshooting-fridges.pdf

 

(Here endeth today’s lesson.)

 

[Derek Uzzell]

lennyhb - 2014-11-06 11:59 AM

 

...Worth noting a lot of the manufacturers now wire the AES fridges so that when in AES mode if there is no gas or mains present the fridge switches to the habitation battery...

 

 

Do you know this to be true, please, or is this a supposition?

 

You’ve instanced your Hymer and a Carthago as having fridges that will switch to habitation-battery operation if gas or mains-electricity is unavailable, but the Thetford fridge in Brian Kirby’s Hymer evidently does not do this and it seems to be contrary to Dometic’s policy never mind good sense (proven by the fact that you’ve removed a fuse to stop it happening).

 

I could happily accept a caveat that “...some manufacturers now wire...”, but I”m wary that “...a lot of manufacturers now wire..” is accurate. If this is indeed the case, which manufacturers, besides Hymer and Carthago, do this?

[Robinhood]

Derek Uzzell - 2014-11-07 8:36 AM

 

lennyhb - 2014-11-06 11:59 AM

 

...Worth noting a lot of the manufacturers now wire the AES fridges so that when in AES mode if there is no gas or mains present the fridge switches to the habitation battery...

 

 

Do you know this to be true, please, or is this a supposition?

 

You’ve instanced your Hymer and a Carthago as having fridges that will switch to habitation-battery operation if gas or mains-electricity is unavailable, but the Thetford fridge in Brian Kirby’s Hymer evidently does not do this and it seems to be contrary to Dometic’s policy never mind good sense (proven by the fact that you’ve removed a fuse to stop it happening).

 

I could happily accept a caveat that “...some manufacturers now wire...”, but I”m wary that “...a lot of manufacturers now wire..” is accurate. If this is indeed the case, which manufacturers, besides Hymer and Carthago, do this?

 

I do wonder whether this may be a glitch in "solar panel" mode.

 

The newer AES fridges have a mode that will allow solar power (if it is available) to supply the fridge.

 

I know Lenny has (significant) solar power potentially available, whilst I don't think Brian has a panel fitted.

 

Logically, one would expect an interlock to avoid switching to solar if not enough power were available, so I'm not at all sure that what is happening is what should be happening under these circumstances, but, given the difference in behaviour, it simply makes me wonder.

 

 

[lennyhb]

Both my Hymer (and my last Hymer) and my mates Carthago were wired like this as standard no solar panels fitted when delivered. I fitted the panels myself. Also according to the manual if wired for Solar, Solar takes priority which in my case it does not it only takes power from the habitation battery if no mains or gas present.

 

As I said the Elektroblock has an fused output for Compressor and AES fridges (marked Kompr./AES).

 

Extract from Elektroblock manual:-

[Robinhood]

lennyhb - 2014-11-07 10:14 AM

 

Both my Hymer (and my last Hymer) and my mates Carthago were wired like this as standard no solar panels fitted when delivered. I fitted the panels myself. Also according to the manual if wired for Solar, Solar takes priority which in my case it does not it only takes power from the habitation battery if no mains or gas present.

 

As I said the Elektroblock has an fused output for Compressor and AES fridges (marked Kompr./AES).

 

Extract from Elektroblock manual:-

 

I've already read, and understand that, but to have it work in the way it does on yours seems counter-intuitive, and different to Brian's 'van.

 

I do wonder whether the wording here applies to the fridge controls, rather than the heating circuit.

 

Since the Schaudt instructions also have the wording:

 

Make sure the AES fuse is only used if the AES refrigerator is connected. Otherwise, the living area battery may get totally discharged. Battery damage is possible.

 

....there is an implicit expectation that an AES fridge will do something additional to avoid the battery being totally discharged.

 

Logically, this may well be explained by the fact that the controls in an AES fridge (but not a non-AES one)have the ability to D+ sense (and should only switch to 12V when it is present).

 

The EBL appears to have a (simulated) D+ output for the fridge - I wonder if for some reason this is permanently live on yours?

 

I do find it difficult to believe that (even ;-)) Hymer would go to the trouble of installing an automatically-controlled fridge, and then deliberately install it in a way that makes it virtually unusable in that mode.

 

 

 

 

[lennyhb]

The Elektroblock has a separate input for the d+ terminal.

Only found out about how they were wired their vans in 2008, my mate had an identical van to mine on his first outing ended up with a totally flat battery, when we investigated we found out why. Queried it with our dealer they confirmed it was wired correctly, also checked with other Hymer Club members, anyone with a van latter than 2007 was wired the same.

 

Doesn't bother me as I pulled the fuse, only works on 12v now when the engine is running, although I do think they ought to make the customer clearly aware of the situation.

[Robinhood]

lennyhb - 2014-11-07 11:14 AM

 

The Elektroblock has a separate input for the d+ terminal.

 

....there is a D+ input to the EBL, but there also appears to be provision for a D+ (simulated) output on the fridge plug.

 

 

[lennyhb]

On the EBL 29 and the EBL101 there is a D+ point which is a link through of of the D+ input I think it is used for the step relay, no D+ simulated output you mention.

[Derek Uzzell]

As will be seen from Page 14 of this document

 

http://benimarownersclub.org.uk/wp-content/uploads/2013/09/PC100_PC200_DS300_ENcircuits-1.pdf

 

some CBE-made systems have specific features relating to AES fridges. The implication seems to be (as lennhb said about his pal’s Carthago) that the 12V power-supply from the leisure-battery is not automatically disabled when the motorhome’s motor is switched off. (As the power-supply is 30A-fused, it’s clearly the supply that deals with the fridge’s cooling.)

 

Motorhome manufacturers do not always follow the advice of the makers of the appliances fitted to their vehicles. Proof of this is how poor many Truma C-Series and Combi heater installations are as a consequence of Truma’s recommendations being ignored.

 

My 2005 Hobby T-600FC motorhome’s Dometic 7-Series non-AES fridge/freezer was wired up in a way that conflicted with Dometic’s installation instructions. Other owners of Transit-based Hobby’s of similar vintage also reported this, saying that it had resulted in operating problems that were resolved by a simple wiring modification. While recognising that the wiring looked wrong, my fridge/freezer worked OK during the 9 years I owned the vehicle, so I never bothered to alter its wiring.

 

Although the Schaudt and CBE electrical systems used by, respectively, Hymer and Carthago apparently can be installed so that the cooling-system of an AES fridge can run directly from the leisure-battery if no alternative power source is available, that doesn’t mean a) it’s a sensible idea or b) that this is the way the fridge manufacturer would have anticipated the appliance being installed. Perhaps Hymer should get together with Schaudt and Dometic (and Carthago with CBE and Dometic) and check that they are all singing from the same songsheet.

[Stitches]

I've noticed that the Aes fridge in Hymer Exsis i578 switches to leisure battery when engine stopped before switching to gas, I'm not sure how long it is on leisure battery beforeswitchingover org how it knows how to?

 

[lennyhb]

Just been having a play with mine, I put the fuse back in and set the fridge running on gas, I then turned off the gas, it did not switch to the leisure battery but tried to relight on gas, after a predetermined time the fault light came up. Switching to manual to battery it runs off the leisure battery if the engine is not running. I also tried the options after running the engine same result.

 

Not sure how Nick came to his conclusion on his Exsis i578 (assuming he has a Dometic fridge) but it certainly does not do that on mine, the battery light on the fridge stays on for the 15 min after switching off the engine but it is not drawing any power from the leisure battery.

 

On my previous van the 7 series fridge would run off the leisure battery in auto mode as does my mates new Carthago.