Forum Discussion
RoyB
Sep 16, 2014Explorer II
When you are saying BATTERY ISOLATOR I am assuming you are referring to a SMART RELAY type battery isolator and not a high current diode type.
The SMART RELAY type monitors the battery voltages and will switch into the alternator system when needed charged but only when the ALTERNATOR is in CHARGE MODE. The ALTERNATOR system also produces the various different stage voltages. I see DC voltages across my truck start battery in the different charge stage modes all the time ranging from 13.2VDC to 14.4VDC.
The real important about the smart relays is they will switch away from your truck start battery/alternator setup when the extra battery is below 50% charge state so to not run down the truck start battery.
Here is a good description on how the BLUE SEA SI-ACR SMART RELAY works.

BLUE SEA SI-ACR SMART RELAY
SI-ACR RELAY functions explained
MORE SI-ACR RELAY INFO
The SMART RELAY type monitors the battery voltages and will switch into the alternator system when needed charged but only when the ALTERNATOR is in CHARGE MODE. The ALTERNATOR system also produces the various different stage voltages. I see DC voltages across my truck start battery in the different charge stage modes all the time ranging from 13.2VDC to 14.4VDC.
The real important about the smart relays is they will switch away from your truck start battery/alternator setup when the extra battery is below 50% charge state so to not run down the truck start battery.
Here is a good description on how the BLUE SEA SI-ACR SMART RELAY works.

BLUE SEA SI-ACR SMART RELAY
SI-ACR RELAY functions explained
MORE SI-ACR RELAY INFO
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