Thetford N145 and Votronic mpp350

[Alanf1]

My Thetford fridge is an SES (smart energy selector) and my solar controller has the ability to send excess solar energy to the fridge if ever there is a surplus.

I can see there is an connection on the solar controller to send a wire to the fridge to enable this. Does anyone know where the connectors are on the fridge to hook this up?

If I can get access to the rear through the vents, is it possible to access the connectors on the fridge from there? I've found an installation manual but I'm not really any wiser as a result. If it's going to be a fridge out job then I think I'll just leave it for the benefit it will give.

[paws]

 

Hi , our solar controller is connected to the electrobloc - a Schaudt EBL267 = this is the connection to the Thetford fridge.. You don't need to wire to the fridge.

 

Hope this is of some help

 

Patrick

[Alanf1]

Thanks, I have a check system so will take a look at the manual and see if I can see where it should be connected on the board.

 

[Alanf1]

Having opened up the board and found a diagram I can see there is a bridge for SES fridge on the board. There is a wire that links the 2 terminals. The circuit diagram says it's a link between the fuse for the fridge and the have battery. If I remove the wire and then connect up to the solar regulator will I then lose power from the battery? There isn't any detail about what to do to wire up the solar regulator in the CBE document.

[paws]

 

Hi. sorry I'm not familiar with CBE equipment.

Hopefully somebody who is can help

 

Patrick

[aandncaravan]

Alan, there is often a loss of understanding during translation on some of these documents, so may I outline how a Fridge on 12v works in relation to Solar and then you may have a better understanding of the issues?

 

For a Fridge to run efficiently on '12v', the main '12v' Element power supply has got to receive at least 13v and around 13 - 17 amps.

When running from a good Alternator supply, a typical modern Fridge/Freezer will be fed 14.4v and around 15amps, depending on the Fridge.

 

Obviously supplying a Fridge with a trigger S+/D+ voltage but then only putting 2 amps into the Fridge 'Cooling' Element might get it to switch from Gas to 12v, but it clearly isn't going to get it to 'cool' at all.

 

So when these documents talk about feeding 'excess' power to the Fridge they sometimes use the habitation battery to make up the shortfall. This is based on the assumption you have already worked out that your Solar Panels will be big enough to run the 12v Fridge Element so any shortfall will be minimal.

 

However, what tends to happen, typically, is that the calculations are not done and the habitation battery provides 12amps and the Solar 1 amp.

Or the scenario above were the Fridge switches to 12v but only gets 2amps so doesn't cool, but gets warmer.

 

Or that the system fails to trigger at all because the excess Solar is actually very few amps and volts, once recharging the battery to put back the previous days TV, Satellite, lights, Laptop, phone, etc. is taken into account.

 

 

If you were to rig the Fridge so it properly runs only off 'excess Solar' you will need about 400watts of Solar, 300watts to provide 15amps to run the Fridge and 100watts to put back the power drawn the night before by the TV, laptop, phones, lights, etc.

 

Even then, obviously, the Solar will only run the Fridge efficiently during the strongest daylight hours and during the longest days of the Summer months. Probably even in these limited circumstances, only in Spain, etc.?

 

 

A typical Fridge uses little Gas.

Most Gas consumption is taken by Heating/Water, Oven, Hob, etc. not the Fridge, which is very efficient on Gas.

A lengthy seasons Fridge gas consumption is unlikely to be more than a single gas bottle, so spending £500 to save £29 worth of gas will take quite a long time to become a sound investment. Possibly 17 years?

Or, in reality, never, as almost all Fridges, and especially Fridge/Freezers will operate much more efficiently on gas, and are pretty poor on 12v.

Also bear in mind that on many Fridge units, the 12v side does not include a thermostat, these are generally only effective on the 230v and Gas side.

 

 

My advice would be not to use 12v to run a Fridge, ever, as most Fridge/Freezers have outgrown the 12v electrical Infrastructure which has not kept pace with the 12v power demand. As a result the voltage drop many Fridge/Freezers cause when driving can have a really detrimental effect on Alternator charging of the habitation batteries.

 

 

If you look back to the Fridges of 1985 they were quite small with smaller 12v demands. The distances covered on 12v in any one 'run' were relatively low, Talbot's were just too slow and uncomfortably to do any different!!!

But in 2018 the Fridges have grown into huge Fridge/Freezers (we have measured 17amps draw on one Fridge) yet the electrical infrastructure is exactly the same as it was in 1985 and the distances covered in one go on 12v power has probably quadrupled?

 

I would guess the 12v Fridge load today is about 6 times what it was in 1985?

 

 

 

[Alanf1]

Really interesting Allan, many thanks for the detailed explanation there.

 

It would appear then it is just not worth it to hook this up, and in doing so would probably make the fridge less efficient as a result. I can't see any positives from setting this up.

With that in mind then I don't think I'll bother and leave it as is.

 

Thanks again for your input here, I really appreciate it.