Blue Sea 120 amp ACR question.

[Hoohaa]

Hi. I'm currently installing an ACR. I would like to know if it's absolutely necessary to wire it to the engine start. I believe it's optional.
On my boat, it's a real challenge to get to and figure out the correct wire at or near the starter motor. I need to use a mirror just to see it.
I could go all the way to the start Pannell but that's allot of effort and distance.
So! Do I wait until my grandson is old enough tie a rope to him and squeeze him into their with a screw driver strapped to his hand. Or can I give it a miss?
Cheers.

[rbk]

They’re wired between two banks, one could be your start. Ideally your charting sources all go to your house bank and the ACR goes between the house bank and your secondary (start) bank not your starter.

[Hoohaa]

Thanks RBK.
I have the 2 main wires to the start and the other to the house.
There is an option to run a 4th wire which takes off from the base Of The act and hooks up to your ignition.
It's called a"Start Isolation". It protects electronics from voltage sags and spikes during cranking.
Read that off the pack.

[BlackHeron]

Originally Posted by rbk

They’re wired between two banks, one could be your start. Ideally your charting sources all go to your house bank and the ACR goes between the house bank and your secondary (start) bank not your starter.

If your ACR is engaged because any charging source connected to either bank such as a solar, wind, or shorepower charger has raised battery voltage high enough to the combining threshold, then the banks will have been combined and NOT separated any longer.

The start isolation input is there to override the relay so that the engine start battery stays isolated from the house bank when the engine is being cranked over to avoid any voltage sags from the starter motor cranking on the start battery being seen at the house bank.




https://www.bluesea.com/support/articles/63/Overcoming_Dropout_of_House_Electronics_during_Eng ine_Starting

[smac999]

No it’s not Necessary . I never use it.

[CharlieJ]

@BlackHeron #4 is spot on.

@smac999 #5 may or may not be correct. Voltage sag caused by starting the engine is a function of the system; voltage drop in the starting circuit, condition of the starter motor, condition of the propulsion engine, etc. If your engine starter sags the voltage when engaged, the boat’s navigational instruments may drop below their minimum voltage threshold and shutdown. Try it without the SI and see. You can correct later if it is a problem.

[cal40john]

The instruction manual shows the optional start isolation wire going to the start switch, not the starter. ( In reality it can go anywhere on the the start wire.)

http://assets.bluesea.com/files/reso.../990170140.pdf

[Hoohaa]

Thanks.
So it looks like it's not going to damage anything if I don't hook it up.
I can always connect it if needed down the track.
Thanks for the quick responses.

[CharlieJ]

@cal40john #7 is also spot on.
Here is the sequence: when the start key (or start button) is engaged to start the engine it also applies B+ to the SI tab which disengages the ACR in a few mS so the starter only draws from the starting battery. When the momentary key switch or start button is released, B+ is removed from the starter solenoid and from the SI tab on the ACR and, if the combining parameters for the ACR are still met, the ACR will re-combine start and house banks.

BTW, these ACRs are bulletproof. I have several installed on loneliness and they can’t screw them up��

[BlackHeron]

If you do eventually put the start isolation interlock in from the ignition circuit be sure to follow all the fusing recommendations from the wiring diagram in the instructions. The same goes for all the fusing, even the ine in the ground from the ACR. They are there for a reason.

The fuses on the battery interconnect wires to the ACR should be sized according to the directions as well, and may be quite large depending on your system. I used ANL fuses and fuse-holders since they are robust, reasonably priced, and commonly available in many sizes as they are used extensively in the car audio world. All of my larger fuses are type ANL.

[rbk]

Originally Posted by BlackHeron

If your ACR is engaged because any charging source connected to either bank such as a solar, wind, or shorepower charger has raised battery voltage high enough to the combining threshold, then the banks will have been combined and NOT separated any longer.

The start isolation input is there to override the relay so that the engine start battery stays isolated from the house bank when the engine is being cranked over to avoid any voltage sags from the starter motor cranking on the start battery being seen at the house bank.




https://www.bluesea.com/support/arti...ngine_Starting

I was worried he was trying to wire the ACR in between his alt and his starter or something along those lines. It wasn’t really too clear with the initial post. I also wouldn’t worry too much about connecting the SI either unless you have a ton of high draw electronics on all the time. Just a chartplotter, vhf etc they can take some abuse.

[moseriw]

You simple have B+ A+ and ground-
Battery charger goes to B "ONLY"
That's all.

[Hoohaa]

Originally Posted by BlackHeron

If you do eventually put the start isolation interlock in from the ignition circuit be sure to follow all the fusing recommendations from the wiring diagram in the instructions. The same goes for all the fusing, even the ine in the ground from the ACR. They are there for a reason.

The fuses on the battery interconnect wires to the ACR should be sized according to the directions as well, and may be quite large depending on your system. I used ANL fuses and fuse-holders since they are robust, reasonably priced, and commonly available in many sizes as they are used extensively in the car audio world. All of my larger fuses are type ANL.

I have fuses. ANL. Mega & the terminal fuses.

[BlackHeron]

I like that ANL fuse bank. Is that a BSS product? Looks pretty slick.

[SeaBreeze-1]

The simple answer to the OP's question is: you can use the start isolation wire or not bother. If you don't use the function, the ACR just doesn't isolate the start battery during the startup process... that's it.

While the instructions say to run the SI wire to the ignition switch where the solenoid wire is attached, it can be attached to the other end where it meets the solenoid on the starter itself. DO NOT attach the SI wire to the starter cable!!

The purpose of Start Isolation is to help protect sensitive electronic equipment from surge and sags created in the starting circuit during startup. In order for the SI function to work at all, your boat must have separated Start and House circuits.

Some boat systems are wired through the basic 1,both,2,Off switch so that everything (electronics and starter) are always combined to the power source, regardless of the switch selection (Batt#1 or Both or Batt#2 powers everything). The SI function won't work in this case so there's not much point in hooking it up. In my own setup, I've added in a second 1,Both,2,Off switch that allows me to power the House and Start loads separately. I can also use this switch for an emergency jumpstart without using the fused House circuit and as an emergency shut off in the start circuit.