Battery Isolation Plan
There is no OEM battery isolator in either my RAM truck or my Eagle Cap TC. I have been unplugging my umbilical cord when I stop to camp, thereby disconnecting house from starting batteries. Whe...
Forum Discussion
I am using the Blue sea 7610 model ACR smart relay here.
The spec says "The ACR senses when the voltage of either of the batteries rises to a level indicating that a charge source is active (13.0V for 2 minutes). The ACR contacts then connect and the ACR applies the charge to both batteries. If the voltage on both of the batteries subsequently drops to 12.75V for 30 seconds, the ACR will disconnect, isolating the batteries."
My setup follows this pretty close. I do notice that the smart relay switches in the second battery at a somewhat higher DC voltage like 14.0VDC verses the 13.0 specified. My battery cable lengths for the second battery is several feet longer than the truck start battery to where my ACR smart relay is installed. This may be the reason for a different DC Voltage ACR switch-over sequence.
It does very well keeping my second battery charged at the same time the truck start battery is being charged by the truck alternator. When the truck engine is OFF then my battery drain on the second battery is isolated from the truck start battery wiring. Your start battery does not get run down on you.
There are other smart relays on the market other than Blue Sea. Blue Sea and SURE POWER Industries seem to be the most popular ones discussed.
In the old days we all used high current diodes to isolate the Batteries but the diodes designed built-in voltage drop in their operations makes it almost impossible to use when you are working with 14.4VDC-13.6VDC-13.2VDC levels associated with our modern smart mode charging systems... Smart relays that switch with has becomes the easiest way to isolate batteries these days...
Roy Ken
The spec says "The ACR senses when the voltage of either of the batteries rises to a level indicating that a charge source is active (13.0V for 2 minutes). The ACR contacts then connect and the ACR applies the charge to both batteries. If the voltage on both of the batteries subsequently drops to 12.75V for 30 seconds, the ACR will disconnect, isolating the batteries."
My setup follows this pretty close. I do notice that the smart relay switches in the second battery at a somewhat higher DC voltage like 14.0VDC verses the 13.0 specified. My battery cable lengths for the second battery is several feet longer than the truck start battery to where my ACR smart relay is installed. This may be the reason for a different DC Voltage ACR switch-over sequence.
It does very well keeping my second battery charged at the same time the truck start battery is being charged by the truck alternator. When the truck engine is OFF then my battery drain on the second battery is isolated from the truck start battery wiring. Your start battery does not get run down on you.
There are other smart relays on the market other than Blue Sea. Blue Sea and SURE POWER Industries seem to be the most popular ones discussed.
In the old days we all used high current diodes to isolate the Batteries but the diodes designed built-in voltage drop in their operations makes it almost impossible to use when you are working with 14.4VDC-13.6VDC-13.2VDC levels associated with our modern smart mode charging systems... Smart relays that switch with has becomes the easiest way to isolate batteries these days...
Roy Ken
