steveandlisa Posted July 2, 2022 Share Posted July 2, 2022 Hello, When travelling, the same as most folks i turn the dometic fridge to 12 volt. I know the fridge only functions on 12v when the engine is running, but can anyone tell me whether it is the hab or engine battery that supplies the power. Thanx Steve Link to comment Share on other sites More sharing options...
buddy Posted July 2, 2022 Share Posted July 2, 2022 The engine battery should be being used to supply the power to the fridge 12v heater element , but only when the engine is running, the leisure battery can also be being used to supply a separate (12v) power supply to the fridge controls.. Link to comment Share on other sites More sharing options...
Keithl Posted July 2, 2022 Share Posted July 2, 2022 Steve, As the engine must be running for the fridge to work then both batteries will be charging so the alternator is actually supplying the power rather then either battery. Are you actually asking which battery is the fridge heating element wired to in terms of wire size and current capacity or some other reason? If yes then it is likely you will either have to follow the wires or ask Bailey. Keith. Link to comment Share on other sites More sharing options...
steveandlisa Posted July 3, 2022 Author Share Posted July 3, 2022 Hi Keith, Sorry :$ , yes i guess i`m wondering as to which battery the fridge heating element is actually wired to. No real reason, i`m just curiuos should a need arise ;-) Thanks again Steve Link to comment Share on other sites More sharing options...
Robinhood Posted July 3, 2022 Share Posted July 3, 2022 ...as Steve says above, it will depend on the convertor's wiring practice. The fundamental commonality is that the fridge cooling circuit will be completed by the presence of a "D+ signal", indicating that the engine is running and 12V is being provided by the alternator. Where that cooling circuit is connected, however, differs (or at least, did). My current 'van, controlled by an Electrobloc, connects the fridge (cooling) circuit to the vehicle battery. AFAIK, this is the most common current (pun intended) practice. For a long time, however, Autosleepers (as an example) connected the fridge cooling circuit across the leisure battery. I know this from bitter experience having blown the fuse in the LB charging circuit, and fully depleted the LB on a Friday night trip to the Lakes (The LB wasn't charging, but the D+ signal was present and continued running the fridge from it). Quite coincidentally, I later fixed the exact same problem for a flummoxed Autosleeper owner who pitched next to me in Ireland (even gave him a new fuse!). Link to comment Share on other sites More sharing options...
rayc Posted July 3, 2022 Share Posted July 3, 2022 The fridge is normally connected to the cab battery but if the leisure battery is also connected to be charged by the alternator when the engine is running, then the fridge is actually connected to both batteries as they are paralleled at that time . Link to comment Share on other sites More sharing options...
Keithl Posted July 3, 2022 Share Posted July 3, 2022 Steve, There is a wiring circuit diagram in your handbook... https://www.baileyofbristol.co.uk/wp-content/uploads/2020/01/2012-Motorhome-Approach-SE-Owners-Manual.pdf It is on Page 6 - 12 (pdf page 45) but only shows the fridge being wired back to the PDU so not much help! Link to comment Share on other sites More sharing options...
thebishbus Posted July 3, 2022 Share Posted July 3, 2022 On our old Hymer, the 12v heating element is wired to the engine battery circuit, but the fridge light to the leisure battery. Brian B. Link to comment Share on other sites More sharing options...
Alanb Posted July 3, 2022 Share Posted July 3, 2022 On vehicles with CBE electrical systems the fridge relay is integral to the 12V distribution board (DS300xx, or DS520xx) and is connected to the habitation (B2) side of the integral split charge relay. This means that in the case of a faulty starter battery (B1) connection, as detailed by Robinhood the fridge will discharge the habitation battery. There are previous threads pertaining to this situation. When EHU is used, it may take sometime for the problem to be noticed. A secondary effect on CBE systems, is that the fridge element current adds to the voltage drop across the split charge relay. Diverting the fridge power to an external relay can yield a significant improvement in habitation battery charging. This was first noted some years ago, by the now deceased Allan Evans. Alan Link to comment Share on other sites More sharing options...
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