About half of my driving is at night with lights on and I have been caught with a "flat" battery (in the Mazda) once after a long EOC ending at a long wait at traffic lights.
After that, I fitted a voltmeter so I can monitor battery charge and at night, I let the engine idle at traffic lights (which doesn't happen that often).
I put the battery on charge when I notice the battery voltage starting to drop to 11.7v during EOC, that's usually only in cold weather, maybe once a fortnight.
It's Summer here now and I haven't charged the battery in a while.
