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[bevedfelker]

When I compiled the Vegas/Axis Owners' Sourced Manual, I researched when the batteries charge and under what conditions. Be low is a paragraph from the manufacturer of the BIRD explains when what battery group is charging when and under what conditions when the engine is running. The manufacturer uses the word "coach" when describing the house batteries and the word "chassis" when describing the chassis battery mounted on the engine.

So basically, if you have a BIRD or a BIM, when the engine is running both sets of batteries are being charged. One set at a time will cycle to charge and BIRD uses the voltage on the battery and a specific time as the criteria when to cycle the charge from the alternator to the set that needs the charge the most.


"Engine Alternator Charging the Batteries

When the ignition switch is turned on and the engine is running, the system senses the level of voltage on the chassis 12-volt system. When this voltage goes above 13.1 volts for approximately 2.5 minutes, as happens when the engine is running normally (normal alternator output voltage of a cold engine is approximately 14.4 volts), it will close the isolator relay providing charging current to the coach battery. This delay allows a cold engine an opportunity to start and warm up before having the heavy load of a discharged coach battery placed on it.

If the voltage should fall below 12 volts for more than about 1 minute, the relay will drop out to feed all the alternators available output to the chassis battery to keep the engine running. This might happen when the alternator is not able to supply enough current to all the loads and charge the coach battery at the same time. When the chassis voltage goes above 13.1volts again, the relay will again close in about 2.5 minutes to retry to charge the coach battery. The resultant flickering of lights would alert the driver of the system overload."