Thetford Fridge

[wildebus]

We can't find any information on the solar panel except that it measures 9x4 squares ie 36 squares but my husband has measured it as 54cmW x 120cmL

That will be a 100W or 120W Panel you have there.

You can measure the volts and amps to find the wattage.

sorry, but not a reliable way to find the power of a solar panel as too reliant on external influences (the sun!) and the internal influences (the solar controller).

The fridge is a Thetford T2090

That is a very nice Fridge-Freezer When I decided to take out my Thetford N180 3-Way, I was close to getting one of those, but opted for a different solution, purely based on priced (the T2090 was around 3-4 x more than I wanted to ideally spend!).
Depending on which model you have, you may be able to reduce the power consumption by turning the freezer section off if not needing it (yes, you lose the freezer, but means can extend your time off grid).
If you haven't checked already, have a look at this PDF - https://www.jacksonsleisure.com/content/pdf/thetford/T2000-Series UM EN.pdf . There is a section in there regarding the drip-tray.


In the summertime, a 100W Solar Panel (if not under shade!) could easily keep up with the demand of a compressor fridge. As has been mentioned, it is also down to what other power draws you have to if it can keep up with everything. Really is impossible to say as everyone uses power differently. Some people on this forum seem to go weeks with a set of 4 AA batteries (ok, slight exaggeration!) and others (like myself) seem to drink batteries.
It really doesn't matter what others tell you what to expect based on THEIR use - THEIR use is not YOUR use. But having said that, the chances are the single battery fitted in a commercially made campervan is most unlikely to be adequate to run a compressor fridge on-grid for any real length of time.
Your Fridge is spec'ed at 280Wh/24hrs. That is in perfect conditions and probably assumes doors are never opened, etc. The amount of cold lost when you USE the fridge in a normal way means that is probably more like 400Wh/24 Hours or more. (My own compressor Fridge Freezer uses just under 50Ah/24 hours - around 600Wh).
If you have a fairly typical 100Ah Lead Acid Battery, that has a TOTAL capacity of 1200Wh, and if you don't drain past 50% (a commonly quoted suggestion), that leaves you with a USABLE capacity of 600Wh available. So even without using any other thing in your van, your fridge will be hard pushed to get you a weekend of off-grid camping (assuming that battery).

Reality is - IMO - if you want to off-grid with a typical compressor fridge, you will need more battery than you likely have; you could benefit from more solar if you are wanting to do more than just run a fridge; and to make the best use of more solar - or even the solar you currently have - the chances are you need a better solar controller to harness the solar energy from the panel. (converters tend to fit the cheapest, most basic controller, rather than the best performing ones).

 

[wildebus]

High-tech compressor performance​

Thetford have expanded on the already-popular performance of the T1090, finding big efficiency gains with the T2090. The fridge's battery efficiency gives you an incredible 8 days (on 2 x 95 Ah batteries), making it perfect for extended off-grid trips. The display has been upgraded to a modern capacative touch screen, allowing you to easily switch between operating modes. The Thetford T2090, for example, includes a Night Mode function, which reduces the noise of the fridge to a whisper, letting you get a good night's sleep. These features can also be controlled via the latest campervan, motorhome and caravan control panels, thanks to the inclusion of CI-BUS compatibility.

Marketing Waffle.

Thanks for all your help. I have run this (above) off the internet which seems to suggest that the fridge itself has 2x batteries that will run for 8 days? I wonder!

I am not sure where you are read that, but to be frank, I think you have either misunderstood what was said, or what you read was just a barefaced lie.
The "on 2 x 96Ah batteries" in the waffly bit is just an example - and TBH a poor one at that in terms of being realistic.

I have also read through your link Robmac which seems to suggest 3 days so it's back to not worrying and try it. Yes park in the sun and hope for the best. We checked behind the drip tray and sure enough there is a little plug but it isn't mentioned anywhere in the manual. The manual does suggest rotating the storage lock in order to leave an air gap for over winter storage but our storage lock is fixed unless I get the screws out ?

 

[merl]

You can measure the volts and amps to find the wattage.

Hey Kev, you'll need one of them fancy clamp meters to measure the current.....

 

[Pudsey Bear]

sorry, but not a reliable way to find the power of a solar panel as too reliant on external influences (the sun!) and the internal influences (the solar controller).


Ah yes of course, not my best subject.

OI'll get me coit.

 

[Pudsey Bear]

If I didn't need the space for my scooter, I'd consider buying a full size domestic fridge freezer and stand it in the hab doorway, it's not going to happen but I did wonder when it first occured just what I would need to run it?

 

[Walkingmox]

Just had a long chat with our nearest dealership and his advice mirrors yours Wildebus ie: get a second leisure battery fitted and a second solar panel and don't remove the plug from the back of the fridge behind the drip tray as it may be a drain or it may be there to stop water leaking behind the fridge into the electrics.
I'll sit back and enjoy the sunset at least we don't have to climb into the camper van to get a top up of vino from the fridge

 

[wildebus]

If I didn't need the space for my scooter, I'd consider buying a full size domestic fridge freezer and stand it in the hab doorway, it's not going to happen but I did wonder when it first occured just what I would need to run it?

Assuming you bought an efficient domestic fridge-freezer, you would more or less the same battery power as if you bought a 12V fridge-freezer. The only things you would have to add is 1) an inverter to provide 240V AC Power and 2) a way to secure the doors when travelling. The money saved on buying the domestic fridge would easily pay for those two additions with hundreds of quid left over.

 

[wildebus]

Just had a long chat with our nearest dealership and his advice mirrors yours Wildebus ie: get a second leisure battery fitted and a second solar panel and don't remove the plug from the back of the fridge behind the drip tray as it may be a drain or it may be there to stop water leaking behind the fridge into the electrics.
I'll sit back and enjoy the sunset at least we don't have to climb into the camper van to get a top up of vino from the fridge

Just remember that solar this time of year is total pants, so don't base decisions on what you might need for the summer on what you are getting now You might find you are ok with what you have come summertime (unlikely, but never know!).
An option for solar is also to get a portable solar kit. Pros and cons with these, but if you would be paying someone to upgrade your solar, some dealers charge a fortune and a portable kit to supplement what is on the roof could be just the ticket at a decent cost alternative.
(rightly or wrongly, I am making an assumption that budget is a factor)

 

[Pudsey Bear]

Assuming you bought an efficient domestic fridge-freezer, you would more or less the same battery power as if you bought a 12V fridge-freezer. The only things you would have to add is 1) an inverter to provide 240V AC Power and 2) a way to secure the doors when travelling. The money saved on buying the domestic fridge would easily pay for those two additions with hundreds of quid left over.

Thanks, If only I didn't need the scooter, if we had a van with a garage I could at least (possibly) put an undercounter one in there and use the 3 way as another cupboard.

 

[r4dent]

Personally, I have been running 2 x 6V 240AH batteries in Paralell which doubles the voltage to 12V and keeps the AH to 240.

I think two 6v in parallel (both negs connected to ground and the two pos connected together. ) gives 480 ah @ 6v.


To get 240 ah @ 12 v they would need to be in series. (Ground ----> [neg battery A pos] ------> [neg battery B pos] -------> Distribution Unit

Any chance of a photo or wiring diagram.

 

[merl]

They are in series, Rob made a mistake when he said parallel

 

[Walkingmox]

Our present single battery is lithium gel but we shall explore the addition of a second battery and another good reason not to watch tv
Thanks for all your excellent advice

 

[wildebus]

I think two 6v in parallel (both negs connected to ground and the two pos connected together. ) gives 480 ah @ 6v.


To get 240 ah @ 12 v they would need to be in series. (Ground ----> [neg battery A pos] ------> [neg battery B pos] -------> Distribution Unit

Any chance of a photo or wiring diagram.

He meant series clearly, not parallel

 

[wildebus]

Our present single battery is lithium gel but we shall explore the addition of a second battery and another good reason not to watch tv
Thanks for all your excellent advice

Having Lithium will mean your current usable power is virtually doubled compared to if it were Lead-Acid of the same capacity, so that is a good sign

 

[r4dent]

He meant series clearly, not parallel

Agreed.

 

[Robmac]

Yeah sorry, swot I meant.

Oddly enough I checked before I posted and must have got distracted and still got it the wrong way round!

 

[rugbyken]

a lot of people with smaller vans ie lack of space make use of power packs to run everything else, expenditure over a mid size lithium is similar and is a flexible option