View Full Version : Blue seas ACR question

05-01-2011, 09:33 PM
I've read every battery thread but still have a question.
I am adding a battery to my X2... The last article i read said this ....
"Hooking up the average ACR is simple: One wire goes to the positive terminal of the starting battery, one goes to the positive terminal of the house battery, and one goes to the boat’s common ground connection. When the relay contacts touch, both batteries are instantly wired in parallel (positive post to positive post and with a common negative post connection at the boat’s common ground)."

So do I not wire anything to a starter or ignition?? It's simply wiring between the batteries?
Just want make sure I'm looking at this correctly. I plan to run stereo and amps off 2nd battery. Leaving all else as is.


05-01-2011, 10:28 PM
This is from the blue seas web site.

"How does an ACR work? An 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′s 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."

Your alternator will supply the charging voltage greater than 13 volts this will cause the ACR to connect the 2 batteries. Or if you connect a battery charger up to the house battery I believe both batteries will be charged.

05-01-2011, 10:30 PM
Ok I got that. Still do not understand how this isolates your main battery for starting purposes only? I am trying to make it so that my #1 battery is always ready for starting and the #2 battery is used for stereo etc.. while sitting and chilling.

I am lost...........

05-01-2011, 10:39 PM
The voltage of your battery at reset and when starting will always be less than 13.0 volts so the ACR will not connect the 2 batteries. Once the engine starts and the alternator starts to output the voltage will rise once the voltage rises and remains above 13 volts for 2 minutes the ACR will connect the batteries together. When you shut off the engine the battery voltage will drop below the 13.0 volt level and the ACR will isolate the 2 batteries.

05-01-2011, 10:43 PM
I see. So there is no need to wire anything to a starter or ignition at all? Simply common ground and + cables from each battery?

05-01-2011, 10:52 PM
Just add a fuse between the negative connection of the ACR and the common ground. 10-15 amps is recommended. Here is a link to the info. http://bluesea.com/viewresource/1366

05-01-2011, 11:01 PM
This may help answer your question. There are a couple of options you can add one is an led to indicate when the batteries are Combined. and the other is to provide a start isolation for electronics as stated below.

"Wiring of the start isolation function of the SI ACR is not necessary for normal operation. However, many boaters find it worthwhile to enable this feature, since it protects sensitive (and expensive) electronics from voltage sags and spikes caused by engine cranking. Remember to install the SI wire to a point at 12V only when the engine key is in the START position."

05-01-2011, 11:04 PM
This whole deal makes me feel like an idiot. So there is a 4th point, being the SI point that I should wire to something that will shows 12 volts when the key is in the start position? Where do I run that wire? Starter?

05-01-2011, 11:12 PM
This should be wired to the starter soleniod wire that has 12 volts supplied to it ONLY when the key is in the start/cranking position. The starter is the easiest place to wire too. I did not use this feature. I simply wired the ACR like your first post.

05-01-2011, 11:26 PM
I wired it the simple way as well + from start/charge batt to ACR + from ACR to house batt, - fused from ACR to ground...done.

05-02-2011, 12:09 AM
Ok I took this pic of my mess of wires tonight on the port side of the engine. There is a yellow and red wire coming off what I believe is the igntion wire to the starter selenoid, correct? If so I can just wire in where that wire is and take that to the starter isolator post on the ACR correct?

And Thrall, I cant make out what you are saying there?? looks like
positive from the starter or charger to ACR?
Positive from ACR to house battery
Negative fused from ACR to ground
Talk to me like a grade schooler!... :)


05-02-2011, 07:12 AM
I tried wiring the start isolation from the key switch with no joy. My result was that the batteries never charged. I finally gave up and went with the simple method. It's been working fine ever since.

05-02-2011, 11:37 AM
Asuuming you're going to do the simple install minus the start isolation feature, guess bturner didn't have any luck with it. I have run mine for a year on the same boat as yours with no electrical problems and it links up the batteries fine.
On our boats, the charging wire (8 ga?), it's the orange looking one in your pic, comes from the alternator to the starter motor and then the 2ga wire from the starter to the battery carries the charging current to the battery. So you don't have to mess with anything in the engine compartment.
Presuming you're adding a 2nd battery under the port seat next to the start battery.....
Run a good wire (8ga or heavier I think there's a reccomendation based on wire length in the instructions) from the + terminal on the start battery to one of the + terminals on the ACR.
Run another wire from the other + terminal on the ACR to the + terminal on your house battery. Hook up a little ground wire with an inline fuse from the gnd terminal on the ACR to a good ground (Iused one of my - distribution blocks as the gnd but you could just hook it to the - on one of your batteries). That's it.
For your house battery, run a dedicated ground (2ga at least) back to the engine block. Don't daisy chain it into the exisitng - wire going to the block.
Here's a pic of my setup minus the ACR, don't have one of those pics on this computer. The dist blocks are a pair for the start battery functions and a pair for teh house battery functions (stereo). They are totally isolated from each other
except for the ACR, so the stereo can never drain the start battery.
Think of each set of dist blocks as the + and minus terminals fore each battery but a more organized way to hook up teh mess of wires. Then I ran one heavy ga short cable to each of the battery posts off of the corresponding dist blocks so the batteries aren't cluttered. My ACR is actually hooked to the 2 + dist blocks not the actual batteries.
In the picture, the 2 big blue wires are coming from the right side dist blocks (stereo battery) and go to the stereo battery. The 2 red wires with tape on tehm come from teh + of each dist block to the ACR (yet to be installed).
Hope this helps

05-02-2011, 11:52 AM
One small thought for guys with Kinetik AGM batteries (and some other AGM's).

The resting charge for those is much higher than the traditional lead acid batteries (13.2 on mine). SO the ACR keeps the batteries connected until the charge is down to 12.75 V or so. The ACR has a draw all by itself. By definition, the batteries discharge until they are both depleted to some degree, not good for the batteries.

05-02-2011, 12:17 PM
I used a Perko switch. Easy to install and you can choose which battery is being used or charged.