Quote Originally Posted by ian ashton View Post
The SI option is virtually pointless, for the following reasons:

-Many times when you start, the batteries aren't combined anyway, due to voltage on the 'house' battery vs. the start battery.

-If the batteries are combined when you start, the ACR will separate House and Start almost instantly, due to the voltage drop from the starter cranking, giving you essentially the same benefit that you'd see from the SI circuit.

-If you are running a single battery, or dual battery without the ACR, you don't have Starter Interrupt - this is how the boats come from the factory, and nobody has had any issues with it for the last 20+ years, lol.

Long story short, save yourself the headache. I'm running my ACR without the SI hooked up.
I disagree with your first two points. To your first point, when you are changing riders and shut off the engine, the ACR will stay combined since the voltage on both batteries will be above 12.75. I have a remote LED on the dash and the light stays on so I can confirm this.

To your second point, the ACR will NOT "separate House and Start almost instantly, due to the voltage drop from the starter cranking". The voltage in one battery has to be below 12.75 volts for 2 min. or below 12.35 volts for 10 seconds for the ACR to open (this is stated in the manual). This is exactly what the SI circuit does - it causes the ACR to open instantly when the starter is engage, if the SI wire is properly hooked up.

No comment on your third point but we hear of lots of cases where someone's stereo suddenly died. How do we know that it's not due to the sudden drop in voltage from the starter being engaged?