Poppy, our 2007 Troll chose us last spring. An imported example, she had had a motor mover and leisure battery fitted at some time in here past along with an on board charger.
All circuits to the battery had in-line fuses, and the feed to the BIP was fitted with a large isolating switch.
We found the original internal incandescent lights a bit dim, and there were no usb or 12v outlets fitted.
I found some very slim led units to fit under the top cupboards, and two touch sensitive types with usb for above the bed. All worked initially, but one of the lights above the bed would trigger randomly on it own, a radio plugged into the new 12v outlet had odd noise in the background of program sound, and when we arrived at the rally last year a fuse in the feeding the lights popped for no reason.
So on investigation, the design of the BIP is not very sophisticated. The leisure battery had been connected to the terminal marked “battterie”, but this is not for a leisure battery ,but for a vehicle battery. When powered it energises a relay to supply the refrigerator. When unenergised, it supplies low voltage ac to the internal lights from one half of the centre tapped transformer. The other half of the transformer is poorly rectified, unregulated dc for water pumps and Truma heater.
So to the solution. The leisure battery is now the heart of the 12v supply. I have fitted a bluetooth solar controller and wired Poppy for a freestanding solar panel. The regulated 12v output from the controller feeds a new fusebox via the isolation switch, and each 12v feed has it’s own fuse withe indicator for fuse failure. The isolation switch now controls all the 12v feeds and battery voltage, 12v load and solar charge can now be monitored wirelessly on a phone.
We have also gained 4 usb’s and a smooth 12v outlet.

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