Dometic RM7 MES to AES conversion

[MikeyGMT]

Hi Folks, 

I successfully installed a solar panel on my van and there's now loads of spare solar energy, and I we have only a small gasflow bottle, so makes sense to use the solar energy to run the fridge. 

 

I have an RM7291L which is MES and reading the manual, there is a PCB conversion kit which upgrades it to AES, which adds a Solar input and the automatically selects the Solar 12v dc or gas. The AES box is about 200 pounds, so it's a fair investment. My question for the forum is, has anyone done this conversion? 

Thanks

Mike  

[Brian Kirby]

Not an answer to your question, Mike, but have you estimated the cost saving in converting from gas to solar? Fridges don't use that much gas so, unless you use your van extensively, I'd think it will take you years to recover £200 on gas alone. Having said this, I appreciate your main interest is to conserve gas due to the small sized cylinder you have.

[Keithl]

Mike,

 

There was at least one recent thread on Motorhome Matters where people asked about running AES fridges on 'Excess' Solar and the general answer was that there will rarely be enough excess current and hence the fridge will be run off the leisure battery (as the solar will change over the input mode) and will then flatten the leisure battery.

 

Allan of AandNCaravan posted answers to pretty much this effect IIRC. Try searching for posts by Allan.

 

Keith.

 

PS Your question is not really a 'Hint' or 'Tip' so I'll move it to Motorhome Matters.

[747]

An underslung gas tank would be a better investment.

[MikeyGMT]

Thanks for the replies, all really helpful, I did a search, but not very successfully :) 

I use the van most weekends and often for a week or so at a time, travelling away for work and stay locally if there's a decent site with public transport or cycling distance to the office. Once setup, I'm not keen on moving the van to get gas (or water). It's the faff and time factor after work - but you just have to don't you. Cost isn't really a concern, as the van saves me loads off hotel fees, and given that the van is £20k, £200 is a drop in the ocean :) 

My T3 Joker had a big underslung gas tank, that was great, refill only a few times a season, and would free up space.  

Meanwhile, I am so pleased with my panel I fitted in April. The panel is 160w with a decent charge controller (Western WRN20), and connected direct to the "leisure" battery. I have avoided the Knaus/Calira charger setup which I have read (on Allan's blog) can have issues! 

The panel quickly refills the battery most days before lunch. It is so satisfying when camping off grid. I do have a big grin, when I see folk struggling with a noisy genny. Anyone wondering, so far the panel has done a great job.  

The battery is the one which came on the van. It is a wet/acid car starter battery (motolite gold calcium egx L75), still working, doing the job, so I have not changed it yet. I plan to upgrade it when it's necessary to do so.  

Everyone's posts were helpful. I found these case anyone else asks / helps searching. http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Dometic-RMD-8555-Solar-connection/49225/http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Votronic-regulator/49184/What I have learnt is the 12v mode ignores the thermostat and does not work too well, so seems sensible to abandon using solar for this particular fridge. Guessing the tech will catch up in a few years.  

Like others I was wanting to make use of a whole afternoon/evening of sunshine being collected but not used. I have seen low voltage immersion heaters used in domestic systems, but I doubt the trumatic water heater in the Knaus will support that, unfortunately it's the one without the 240v helper sleeve heater. 

Future designers of camper tech may think about getting the toys to work together. For example, the heat from the fridge could heat water. Just dreaming...

All good stuff, learning loads, and getting spec for the next one.   

Thanks again!

[Derek Uzzell]

MikeyGMT

 

I vaguely recall someone on this forum having had major problems with a Dometic non-AES fridge/freezer and Dometic giving him as a goodwill gesture an AES ‘kit’ that he retrofitted successfully.

 

This was years ago (and finding the forum thread may be impossible now) and may well be academic in any case as the final posting in this MHFacts thread said that (by 2009) Dometic had discontinued marketing AES conversion kits for 7-Series appliances.

 

https://forums.motorhomefacts.com/49-tech-mech-chat/56143-can-i-retrofit-automatic-energy-selection-dometic-rm7361.html

 

This 2011 MHFacts thtread also suggests this.

 

https://forums.motorhomefacts.com/49-tech-mech-chat/88660-dometic-aes-mes.html

 

(If you have been able to find a source for a (£200) AES conversion kit for a Dometic 7-Series appliance, could you identify that source, please, just in case someone else might want to try retrofitting the kit.)

[MikeyGMT]

There's a couple on ebay.co.uk and ebay.de search Dometic RM7 AES PCB.

 

Thanks Derek. Sure, found the PCB part here too http://www.dometic-service-shop.de/epages/79300988.sf/de_DE/?ObjectPath=/Shops/79300988/Products/241277120 

Search on the part no and you see loads of results -  https://www.google.co.uk/search?q=241277120&oq=241277120&aqs=chrome..69i57j69i60l3.698j0j7&sourceid=chrome&ie=UTF-8 

 

Loads in France actually, as little as €190. 

But not the fascia panel. Maybe that is a scrappy search! 

 

You know, I think I am just going to order it! 

[Derek Uzzell]

As you are aware, an AES Dometic 7-Series appliance has a different control-panel (fascia) to the MES equivalent, with an extra position and LED indicator on each control-switch and (apparently) a dimmer for the LEDs.

 

There was no obvious reason to think that Dometic Part Number 2412771202 would no longer be available, but this part’s purpose would normally be to replace the same part that had failed on a 7-Series appliance that already had the AES capability. I’m fairly familiar with Dometic 7-Series fridges and I’ve always assumed that the 'conversion kit' would comprise a minimum of two elements - an electronics unit (pcb) and an AES-style control-panel - with possibly other parts too. But I’ve never seen a conversion kit nor a description of what it includes.

 

I don’t know if merely fitting Part Number 2412771202 would satisfactorily convert your MES fridge to AES operation. Given that your fridge is 13 years old and Keithl’s comments above, I wouldn’t attempt the conversion myself, but you’d be wise to check with Dometic what parts were (are?) in the conversion kit and whether just swapping the pcb would be enough.