Bi-Directional Isolator Relay Delay by INTELLITEC
Intellitec‚€™s Bi-Directional Isolator Relay Delay‚„Ę offers a new approach to charging batteries in an RV application. Unlike prior systems that only allowed charging the RV battery from the engine‚€™s alternator, the Bi-Directional Isolator Relay Delay‚„Ę charges both batteries when either one is being charged. When the coach is being driven, both batteries will be charged from the engine‚€™s alternator. When the coach is plugged into shore power, both batteries will be charged from the converter. If neither battery is being charged, the batteries are fully isolated. The controller also senses heavy loads on either battery to prevent the wrong battery from being inadvertently discharged.
It operates by sensing the voltage on both batteries. When either of these volts exceeds 13.3 volts for approximately 12 seconds, which happens when either battery is being charged, the control will close the isolator solenoid, connecting the two batteries together, charging them both. (Normal charging voltages are from approximately 13.8 to 14.4 volts.)
After the solenoid has been closed, the system continues to sense the voltage. If the ignition switch is off and the battery voltage drops below 12.8 volts for approximately 5 seconds, which might occur when the converter is heavily loaded, the solenoid is opened to prevent the chassis battery from being discharged by the coach loads. When the voltage goes above 13.3 volts again for approximately 5 seconds, the solenoid closes again.
If the ignition switch is on, the control allows the voltage to drop below 12.0 volts for approximately 5 seconds, before the solenoid is opened to insure the alternators full output is available for important chassis functions. When the voltage goes above 13.3 volts again for approximately 5 seconds, the solenoid will close.
My BIRD didn't work. I installed one of these. Simple wiring and it works great. About $65.00 delivered. You can probably use your relay. If not they are available for $25.00. There is another one for diesel with a generator input.