to add to the confusion
Technically there is NO "battery separator relay"
the BIRD aka "Bidirectional relay control" is just a control board
the battery disconnect solenoid, is separate from the Charge 'Combiner relay/solenoid"
the chassis aka vehicle wiring and charging is different and separate from the HOUSE/RV wiring
the Combiner relay Or diode battery isolator, is there so the alternator will charge the house batteries while when the engine is running
the BIRD, IF one is there controls the combiner so that chassis can be kept charged even when parked
its a two way switch, which ever side is HOT and charging, gets charged first, and then the control closes the combiner relay to charge the other set
with the engine running the combiner will NOT be engaged until correct voltage level is reached at the chassis battery then it will engage the combiner to charge the house
so if both are low, the chassis is charged first, when the engine is running
this could take minutes or even an hour
it also does the same thing when parked, and plugged into shore power, but in reverse
the house must reach the charge setting, before it will engage the combiner relay and charge the engine/chassis battery
this is the main function of the bird, secondary function it saves the alternator, by keeping it from being over worked, LOW/DEAD house batteries will not come online until the engine/chassis batteries are charged
quite frankly, i think they are a royal pain and do not like that system
