Electrolux RM4505 discharging cab battery

[Steve T]

Hi all.

I hope someone out there can offer some advise or information about my problem. I have an Electrolux RM4505 fridge freezer with AES (auto energy selection). When I run it on either gas or 240v it drains my cab battery in approx 5-6 days. Which causes one of those will it or won't it moments when it comes to starting the engine. I realise it needs a constant 12v supply to run the electronics on the control panel but I would have thought that a fully charged cab battery would have powered that for months rather than days. I would be grateful if anyone can advise whether this is correct or whether I have a problem, and if so any tips as to what it could be.

 

Thanks in anticipation

 

Steve

[tonyishuk]

Maybe its not so much the fridge as battery also being drained by the ECU, burglar alarm and radio all on standby.

 

My rather elderly battery only lasts a week when standing unused. Thats just radio, ecu and alarm.

 

rgds

[Steve T]

Hi Tony

Thanks for the suggestion but the battery is only about a year old and in good condition. without the fridge on it stays charged for several months. The fridge is definitely the cause of the problem.

 

Steve

[Derek Uzzell]

Steve:

 

My understanding was that (for the very reason you mention) AES fridges should take 12V power for their electronics from the motorhome's leisure-battery not the cab-battery.

 

Pretty sure Swift wired AES fridges to the cab-battery initially, resulting in lots of unhappy owners of Swift Group motorhomes who camped off-site for longish periods finding their cab battery well discharged when they came to re-start their vehicle.

 

However, 5-6 days isn't very long, so I think you need to check how much current your fridge is actually drawing from your battery.

[johnsandywhite]

:-D Hi Steve. It would perhaps help to know what Motorhome you have, Some have switches to choose the Motor or Coach battery. I have had this on 2 of our Motorhomes. When the Motor battery is chosen and the F/F is ON it used to drain the battery within a few days. That is before I found out about the switch. :'(

[Steve T]

Thanks Derek

 

Your thoughts make a good deal of sense. wiring it to the leisure battery was something I had thought of doing and will. But I agree with you that 5-6 days isn't very long and there could be a problem with the control panel which I obviously need to get checked out.

 

If there is anyone out there that just happens to know off the top of their head :-) the approx amount of current, the control panel should draw, I'd be grateful.

 

Steve

[Steve T]

Hi John and Sandy

 

It's heart warming to know so many people are willing to help.

 

My van is a Auto Trail Commanche, but isn't standard as it was made for the German market and is different in several ways. As far as I know there isn't a switch to manually select either cab or leisure battery, but thats not to say that it isn't hidden away somewhere I've yet to find.

 

Steve

[Derek Uzzell]

Steve:

 

Can't help with the current-drain for the electronics - I did look in my Dometic Manual before replying, but the information isn't there.

 

The Manual advises use of the leisure battery as the electronics' power source, and I note that some old MMM DIY-type articles on how to fit an AES fridge showed the appliance connected to the leisure battery.

[enodreven]

Hi, Steve T

 

I have mentioned this before regarding the 12 volt heater that is used to help reduce the condensation on the Electrolux Fridge Freezer, It states in the hand book that this should be turned off when you aren't on hookup, however if yours is wired differently then just may be the hookup supply isn't replenishing the battery that supplies the power to this heater ??

 

Its just worth checking if its switched on or not, on mine the switch to turn it off/on is on the underside of the fridge/freezer control panel (where the knobs are) and is only accessible when you open the door, its a really small switch set up into the control panel so you have to look hard to find it.

 

Hope that helps

Braunston

[Brian Kirby]

braunston - 2008-09-02 10:37 AM Hi, Steve T I have mentioned this before regarding the 12 volt heater that is used to help reduce the condensation on the Electrolux Fridge Freezer, It states in the hand book that this should be turned off when you aren't on hookup, however if yours is wired differently then just may be the hookup supply isn't replenishing the battery that supplies the power to this heater ?? Its just worth checking if its switched on or not, on mine the switch to turn it off/on is on the underside of the fridge/freezer control panel (where the knobs are) and is only accessible when you open the door, its a really small switch set up into the control panel so you have to look hard to find it. Hope that helps Braunston

That sounds quite likely.  The heater in question is, I believe, actually on the door seals of the freezer section, and is intended to prevent any condensation on them from freezing, and so freezing the door closed.  Good suggestion.

[johnsandywhite]

8-) It could be the AES:-

 

AES - Automatic Energy Selection

 

This Automatic Energy Selection really pays off. You switch it on once, that's it. The advanced AES system automatically selects the best energy source, in the hierarchy 230 Volt, 12 Volt and gas.

 

When you start the fridge for the first time you set the cooling temperature you desire. The system will maintain this temperature, regardless of the power source or the outside temperature. Whether you are moving or stationary, the best energy source is always used. When the engine is turned off, the system waits 15 minutes before switching from 12 Volt to gas. This delay ensures that gas operation is not possible when you stop at a petrol station. The system measures the voltage continuously (even in mains stationary mode, which is very useful not only in Mediterranean countries) and switches to gas if it detects a voltage drop to ensure sufficient cooling performance.

[Derek Uzzell]

Steve's RM-4505 fridge/freezer has been out of production for quite a few years and (I think) may be one of the earlier AES models.

 

The electronic control-system fitted to all Electrolux/Dometic AES and "Powerfridge" appliances needs a 12V power-supply that is continuously available when the appliance is switched on.

 

This supply may be taken from the leisure-vehicle's 'motor-battery', in which case it would need to remain live when the vehicle's ignition-system were switched off.

 

Alternatively, the supply can be taken from the motorhome's 'leisure battery', in which case the supply must bypass any habitation isolation-relay fitted.

 

Logically, the 12V supply for the electronics should come from the leisure-battery, as, if this battery is discharged by the fridge being left on inadvertently for a long period, the motorhome motor's starting capability will remain unaffected. Additionally, it's the norm for motorhomes to have an on-board facility to charge the leisure-battery via a mains hook-up, but it's pot-luck whether this facility is provided to allow charging of the motor-battery. (This was what caught out some of the Swift motorhome owners whose AES fridges had been installed with their electronics powered from the motor-battery. Even when the motorhomes were on campsite hook-up, with their leisure-batteries' charge-state being constantly replenished via their on-board chargers, the AES fridge was stealthily draining the motor-battery that wasn't being topped-up by the on-board charger.)

 

There was a recent MMM letter warning that, if you don't switch a Dometic AES or Powerfridge appliance fully Off and the motorhome stands idle for an extended period, then the battery to which the fridge is connected will become discharged from the electronics' constant power drain. But the exact drain was not stated. I guess it's possible that the electronics on older appliances, like Steve's, are more power-hungry than the present ones.

 

I'm not sure if all Electrolux/Dometic fridge/freezers have frame-heaters, but, if the RM-4505 has one and it's left on, then that would definitely drag the battery's charge-state down. My RM-7651's frame-heater has a prominent red LED to show it's in operation and the heater's selection button is easy to see on the fridge's front panel. If Steve's heater has the same selection-switch position as Braunston's and there's no visible indicator to show the heater is operating, then (as has already been said) it's certainly something that needs checking. (Surely even Electrolux wouldn't be so perverse as to provide a 12V power-sapping frame-heater that can function even when the appliance is switched off and that has an 'invisible' On/Off switch, without also providing some sort of obvious tell-tale (like a big glowing LED) to warn that the heater is operating?)

 

Not exactly sure what Brian's "on the door seals of the freezer section" means. Dometic's Manual for my fridge says that it has "frame heating (12vDC/3.5W) around the freezer compartment". The heater is built into the freezer compartment's front frame against which the flexible seals on the freezer-door abut when the door is closed. I've never used the heater in anger, but I did switch it on today as an experiment. The surface of the frame did heat up, but this warmth was only evident on the lower horizontal part (ie. the crosspiece that carries the door-catch). Don't know if that's all the heater is supposed to do, or whether, if I'd left the thing on longer, the other three faces of the freezer's frame would have warmed up. If it's intended to prevent the freezer-door freezing shut, then I would think all 4 faces would need heating to do the job properly.

 

While I was GOOGLE-ing about, I came across the following link that might prove useful:

 

http://gasrefrigeration.net/dometic_manuals.htm

[Silicongyro]

Derek

I have a Dometic 6505 AES unit - with the heater cable arrangement as you describe. However the manual for this model is quite clear that the heater cable heats the metal frame between freezer and fridge sections simply to evaporate the water condensation droplets that may appear in "summer months of high humidity" ie all the time at the moment! It is nothing to do with stopping the door freezing shut.

The switch is hidden under the control panel - with no lit "on" indicator. I have disconnected the switch to stop inadvertant current being drawn. The water droplets do form but I find them of absolutely no consequence.

 

As an aside on this topic, I found and purchased a replacement main electronics unit for this fridge available at partmaster.co.uk - under the electrolux name and priced way below dometic or their general agents offers.

[mike 202]

I had a similar problem in a Swift Bolero with an auto selection fridge run from the leisure battery. It took 0.4 amp. That works out at 24 hours X 0.4 amp = 9.6 Amp/hours used per day. So theoretically a 100Amp/hour battery will last for 100 divided by 9.6 gives 10 days to total discharge. Add engine management, alarm etc then reality bites with maybee 4 to 5 days.

 

I got round the problem with an 80watt solar panel and a "Battery Master unit" which diverts excess power from the leisure battery to the engine battery, expensive I know but so is running a motorhome. I felt the peace of mind was worth it. I have not had any problems since. Hope that helps. If you need any clarification please just ask.

[Derek Uzzell]

Silicongyro:

 

As Braunston said, Dometic's frame-heater has come up before on this forum. See:

 

http://www.outandaboutlive.co.uk/forums/forums/thread-view.asp?tid=12694&posts=9

 

Although I was aware of the heater's stated purpose, like Brian I've often wondered whether its secondary role was to unfreeze the freezer-compartment door. Installing a heater just to evaporate a few drops of condensation always seemed over-kill to me, but it made better sense if the heater were also a door-freezing countermeasure.

 

I just don't understand why Dometic has chosen to wire the frame-heater so that it can operate with the fridge/freezer switched off. I can't imagine any scenario where I'd want to employ the heater without the fridge also being switched on, but it's easy to predict what's eventually going to happen if the heater is left on after the fridge has been switched off - a very flat battery.

 

Mike-202:

 

I think you meant to say that your AES fridge's power comes from your Bolero's engine-battery rather than from its leisure-battery.

 

If it's normal for AES fridges to draw 0.4A, it's hardly surprising Steve's battery has a tough time. Makes one wonder why motorhome manufacturers don't just wire these appliances to the leisure-battery in the first place, as it's the common-sense thing to do. OK, there will still be the need to replenish the leisure-battery's depleted charge somehow (solar panel, 230V hook-up, etc.), but at least the motorhome's starting capability won't be harmed.

 

(I can't swear to this, but I had a feeling Swift Group had recognised that powering AES and Powerfridge appliances from a vehicle's engine battery was not the greatest of ideas and would re-jig the wiring if motorhome owners complained loudly enough.)

[Steve T]

Hi Braunston

 

I can't thank you enough for your reply. You're bang on the mark with the heater switch and where it hides. I've had this motorhome for seven years and I didn't know it was there, ( sad I know :$ )

So this very morning I lifted the bonnet and with multi meter in hand, disconnected the battery and set about mearuring the various current drain scenarios. First, with fridge switched off I got a reading of 9mA (presumably the clock). Secondly, with fridge on I obtained a reading of 440mA which is roughly what I would expect from the control panel. Thirdly I switched the fridge and heater on and to my horror it initially gave me a reading of 3.2Amps, now thats power hungry. I'm assuming that the heater is thermostatically controlled and is continually switching on and off but it's obvious to see now, why my poor battery is struggling.

 

Fortunately for me Solar Solutions are just around the corner so I smartly trotted off to them to see if they could help. I'm glad to say that they have what appears to be the answer, which is BatteryGuard. I'm sorry if I'm teaching some people to suck eggs but it's new to me. Apparrantly it charges the leisure battery first then transfers the charge to the cab battery. So if you're on hook up and the leisure battery is fully charged it's continually charging the cab battery. So fingers crossed no more heart sinking moments when you turn the key and it just clicks.

The earliest I could get it booked in is 3rd Oct but I'll keep you all posted as to the outcome.

 

Thanks to everyone who has pondered this problem and given me your invaluable ideas and suggestions.

 

Regards

 

Steve

[Derek Uzzell]

The "Battery Guard" name seems to be used for various gizmos that can either protect a battery from being discharged below a certain level, or can transfer charge from a fully-charged battery to one with a lower charge-state. There are a few of the latter type about, ranging from a £9 one from Maplins, through a £23 one from CAK Tanks, up to the "Battery Master" marketed by Van Bitz at around £62.

 

For motorhomes, they normally seem to be employed to feed charge from the leisure-battery to the engine-battery to maintain the latter's charge when it's being depleted by an alarm system. Often a motorhome's on-board charger can only charge the leisure-battery and, in such cases, these devices permit automatic simultaneous trickle-charging of the vehicle's engine-battery. They are also useful to allow (like Mike's Bolero) a solar-panel's 'spare' charge to be fed to the engine-battery once the leisure-battery has been fully charged-up.

 

A drain of 3.2A when the frame-heater is switched on is pretty darned heavy - I notice that Braunston mentioned 1.5A in the earlier thread. Having studied my Dometic manual again, this time more carefully, I realise that I was caught out by the dreaded Continental mathematical comma and had read my fridge's frame heater' current-usage of 3,5W as 35W (hence around 3A at 12V). In fact it's 3.5W, so 10 times less! Even that will pull a battery down though, given enough time.

 

Some of these 'battery-balancing' devices are designed to transfer only a limited amperage and 3.2A may be well above that threshold. If the engine-battery is being seriously depleted, it will make sense to have a device that can keep up with that loss.

[Steve T]

Hi Derek

 

Thanks for the advice, but I intend to do what siliconqvro above has done and turn the heater off, that way I only need to replace the 400mA that the electronics is drawing.

It would have to be a substantial solar panel to try and keep up with a 3.2 Amp drain, so I'm not going to try. Once I've had the BatteryGuard fitted I'm going to power on the fridge without the heater and leave it to see how long it lasts. Hopefully a good deal longer.

 

Steve