Re: One battery or two
wouldnt the dead starter battery be locked out in the combine setting? so in reality if the start battery goes dead. the ACR will lock it out when the combine switch is on so that the house battery goes directly to the starter?
Under voltage lockout?will not close when the lower battery is below 10.8V at 12V operation
The ACR is an Automatic
CHARGING Relay. It is connected between the alternator and the batteries. It has
NOTHING to do with which batteries are powering the starter or accessories. That is controlled entirely by the switch. The "disconnecting" referred to in the specs is referring to the fact that even though the ACR is wired between the batteries, no current can flow through the ACR when you're trying to start the boat.
Current will flow from the higher to the lower voltage potential. When you're trying to start your boat, the starting battery will drop down a couple of volts. If the ACR didn't disconnect during starting, the second battery would try to flow current to the starting battery through the ACR. The ACR cannot handle starting currents.
The "
Under voltage lockout?will not close when the lower battery is below 10.8V at 12V operation" in the specs is referring to the fact that the ACR
WILL NOT CLOSE and therefore try to charge both your batteries if one of the batteries falls below 10.8 volts. IT HAS NOTHING TO DO WITH THE STARTING CIRCUIT. The LED will not be lit and you know that you have a problem with one of your batteries.
As you can see from the Blue Sea ACR diagram below, the ACR is only between the batteries. The switch controls which battery is the starting battery.
To try to make it as simple as possible:
The "A" terminal on the ACR is connected to one battery and your alternator.
The "B" terminal on the ACR is connected to the second battery.
If both batteries are good, the ACR (Automatic
CHARGING Relay) will close when the engine is running and both batteries will charge. The LED comes on when it closes so you know both batteries are charging.
If the second battery is bad, the ACR LED will blink. It will be trying to close but will open again immediatly because the second battery is bad.
If your primary battery is bad, the LED will not come on at all. The ACR will never try to close. This is so your bad battery will not pull down your good second battery.
All the ACR is doing is automatically charging the second battery. It just keeps you from having to remember to move your switch back and forth to keep both batteries fully charged.
Both the batteries in my boat stay fully charged, even though my switch has been set on #1 without moving for over 2 years. If my #1 battery goes bad, I can move the switch to #2 and have a fully charged battery totally isolated from the bad one.
