This is how the BIRD operates and was taken from the documentation for the BIRD for diesels:
The Bird constantly senses the voltage on the auxiliary and chassis batteries. If either voltage is above 13.1 volts, which indicates the batteries are being charged, the control closes the isolator relay. This parallels the batteries, charging them both. If the ignition is off and the voltage falls below 12.5 volts for approximately 1 minute, the relay will open to prevent the auxiliary loads from discharging the chassis battery. When the voltage goes back above 13.1 volts, the relay will close again.
If the ignition is on and the voltage falls below 12.0 volts for approximately 1 minute, the relay will open to prevent the auxiliary loads from over-loading the alternator and discharging the chassis battery. When the voltage on the chassis goes back above 13.1 volts, the relay will close again. Allowing the batteries to stay connected together to a lower voltage helps charge a heavily discharged auxiliary battery more quickly with the varying output of the alternator.
A Gen Set lock-out input is provided to isolate the batteries to prevent conflicts if both the converter/gen-set and alternator are trying to charge the batteries at the same time. When this conflict occurs, it can cause the dash alternator indicator light to illuminate in error and may cause 120 volt circuit breakers to trip.
If the Gen Set is running, the chassis battery and coach battery will be isolated. In this case the chassis battery will be charged by the alternator and the coach battery will be charged by the Gen Set. In the event that the chassis engine is not running, the chassis battery is isolated and will not be discharged by auxiliary loads.
2007 Newmar DSDP 4023
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