Query re 12S Supply to Battery and Fridge.
My daughter’s Volvo V50 and my Volvo 940 are both equipped with twin 12N/12S towing electrics with “smart” relays for the 12S.
Our caravan is a 1994 Bailey Pageant CD Auvergne fitted with a ZIG X2 battery charger and an Electrolux RM2260 fridge.
When I recently checked the output of pins 2 (battery) and 6 (fridge) of the relevant sockets on each car I found that:
The 940 – with engine on regulates at 13.5 volts
when engine switched off drops to 12.3 volts then abruptly to 0 volts..This is what I expected.
The V50 – with engine on regulates at 14.5 volts
when engine switched off drops to 12.5 volts volts then abruptly to 0 volts..
Again this is what I expected, although the regulating voltage is rather higher than I expected.
When the caravan 12S is connected to each of the respective cars and the voltage checked at the caravan battery connections (but with battery disconnected)
with engine on they each regulate at the same voltages as above BUT
when engine switched off the measured voltage reduces gradually past 12.3 volts and continues to reduce gradually (with the rate of reduction slowing as the voltage reduces) until 0 volts
I’ve checked the caravan wiring diagram in the owner’s handbook but cannot see any reason for this
Could someone explain this to me please?