The charging system is a 90 amp Sterling Alternator to Battery Charger...should charge 'em up in less than 40 hours!!! As well as a standard van mounted 6amp charger for overnight charging on a hook-up. An 11amp Absaar charger for running off of our generator in emergencies...we may upgrade this to a 25-40amp depends on if we come to use it more often than just emergencies.
The Sterling has a split charge diode built in to it, which does the job of a split charge relay....I have a battery selector switch built in to the distribution board (3-pole, centre off)...do you think i will need a relay as well? Are you are suggesting a split charge relay, to split the charging route...if so, the diode has that covered...if not please elaborate...i am all ears...thanks.
I have a battery condition meter...switchable from engine to leisure banks. I'm thinking of getting a Nasa digital battery meter...with load display and time until discharge...very handy.
I was thinking of fusing the battery charging run at the battery end, in between the battery and charger and in between every battery on the battery bank positive chain (to minimize risk of a short dropping every battery's charge)
With regards to fridge fusing BJT...i was simply thinking that if i have to flick a switch to change power source on my fridge every time i want to change it, as i do have to because i have a three pole switch (12v, gas, mains)built in to the fridge itself, it would be simple to have another switch located immediately above allowing me to route 12v power to the fridge on demand. Not for any extended period. Just in an emergency.
The scenario that made me think of this was this...We are going to live in the French Alps for the winter...sub-zero every day and night for months...if one night we find our gas to be low and cannot replace our tanks until the morning, or at worst at on a Saturday night and we have to wait until Monday morning, it would be useful to be able to use 12v to keep the fridge cold...whilst the low level gas can be used to keep us warm. This is very unlikely to happen but who knows.
Fatalhud...thanks for the override idea...that seems to be the best of both worlds. Relay as standard, with the option to use 12v if absolutely necessary.
Thanks so much to all who replied. Ingram...i hadn't thought of that...12v fridge runs less efficient than mains or gas? I will have to ponder that one.