1 or 2 SBI's with 2 auxiliary batteries

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1 SBI with 2 auxiliary batteries.

Using this connection:
After the car starts & the start battery reaches 13.5V, the SBI12 operates and starts charging the auxiliary battery and the caravan battery.  The SBI12 now allows the alternator to charge the 3 batteries.  When the car is turned off and the batteries fall below 12.7V, the SBI12 switches off and the caravan 12V equipment draws from the caravan battery and the auxiliary battery, without discharging the start battery.

2 SBI’s with 2 auxiliary batteries.

Using this connection:
After the car starts & the start battery reaches 13.5V, the 1st SBI12 operates and allows charge to the auxiliary battery.  When the auxiliary battery reaches 13.5V, the 2nd SBI12 operates and allows charge to the caravan battery.  The alternator now charges all 3 batteries.  When the car is turned off and the batteries fall below 12.7V, the SBI12’s switch off and the caravan 12V equipment only draws from the caravan battery, without discharging the start or auxiliary batteries.

Updated: Oct 29, 2009 9:23