The resurrection of Doc, bringing a 20 year old neismann Bischoff Flair back to life after 12 years off road. (67 Viewers)

[TinaLes]

berni109
Under normal conditions when the engine is not running the CBE unit is fed from the leisure batts, however when the engine is running power is sent from cab battery/alternator to the CBE post B1 to charge the leisure batts, run fridge etc from post B2.
With a B2B fitted the Leisure batts will be charged directly from the Cab Bat/Alternator to the leisure Batts,but not via the CBE unit which will be isolated with the new normally closed relay opening when the engine is running
The Hab electrics/Fridge will be powered when the van engine is running from the leisure batts and not the cab batt/alternator as the original feed will be disconnected replaced by the relay fed from the normally open contact from the leisure batts.
I hope that makes sense, its as the wiring diagram shows if you look at how the NO/NC relay contacts are wired.
LES

 

[berni109]

TinaLes yes so the as the off-grid solution shows some of the amps being pushed into the hab battery by the B2B is instantly being sucked straight back out to power the fridge when driving. (Simplistically)
Whereas effectively cutting the charge wire (with a relay) after the hab electronic controller puts all the B2B output into the battery and the fridge and any other 12v consumers stay exactly as they are.
Perhaps using the KIS* principal is just to simplistic and I am missing a fundamental point.