Installing Blue Sea ACR

[Senorjacob]

Hey all,

My plan is to install the ACR as a way to learn more about marine wiring and learn more about my boat’s DC system. I recently had my local marina install a Balmar SG200 and I learned a lot by watching that install. Still have more to learn though.

I think I understand how to determine the wire gauges that I need to go from the ACR posts to the positive sides of both my house bank (2 AGMs) and my starter/reserve bank (1 AGM). Since I have an 80am Hitachi stock alternator on my Yanmar, I believe I need 4 AWG wire (since the it will run about 2 to 3 feet to the battery) and a 100-125amp fuse (using a MRBF terminal fuse block). What I can’t seem to find is what gauge wire I should use for the ground wire from the ACR to the negative side of the battery. I’ve looked high and low but I haven’t found anything saying how big that wire should be. The instructions for the ACR says it needs a 1amp fuse, but that’s all it says. Can anyone here point me in the right direction?

In addition to all of this, I’m trying to trace my alternator wires to see which bank it’s connected to. It’s been difficult but I think it’s wired to the common post of the 1/2/Both switch, which makes sense since that switch determines which battery gets the charge. My thought is that, with the ACR, I will keep the 1/2/Both switch dialed to 1 (house) or off. I will start my engine with the house and whenever there is a charge current either from the alternator or shore power, my house will be the first to receive the charge and the ACR will handle balancing the house with the starter/reserve. Is that the right way of thinking about this?

Thanks!
Jake

[wikakaru]

I think I understand how to determine the wire gauges that I need to go from the ACR posts to the positive sides of both my house bank (2 AGMs) and my starter/reserve bank (1 AGM). Since I have an 80am Hitachi stock alternator on my Yanmar, I believe I need 4 AWG wire (since the it will run about 2 to 3 feet to the battery) and a 100-125amp fuse (using a MRBF terminal fuse block). What I can’t seem to find is what gauge wire I should use for the ground wire from the ACR to the negative side of the battery. I’ve looked high and low but I haven’t found anything saying how big that wire should be. The instructions for the ACR says it needs a 1amp fuse, but that’s all it says. Can anyone here point me in the right direction?

Remember when using wire gauge ampacity tables that, unless stated otherwise on the table, the distances are for the length of the entire circuit, not the length of an individual wire in the circuit. This is a common mistake many people make, especially when using duplex wire (which obviously you are not doing in this instance). But using the duplex wire example, if you are running a wire to a device and the length of cable you installed is 10 feet, then the length of the circuit is 20 feet, because the electricity has to travel out one conductor in the duplex cable and back through the other. Draw up an accurate wiring diagram of your battery system, then measure the length of the individual wires in the circuit, follow the paths the electricity will take, and determine the total distance. If you are adding a device in the circuit like your ACR, then you are increasing the total circuit length, and because of that you may be exceeding the ampacity of the already installed wires. Double-check their gauges to make sure this isn't the case.

I'm not sure what brand of automatic charging relay you have, but this one from Blue Sea (https://www.bluesea.com/products/7610/S ... 4V_DC_120A) says the cable size needed to meet the rated capacity of the relay is 1/0 gauge (though they don't say what length of circuit it was calculated for, so it's kind of a useless number).

Smooth sailing,

Jim

[John Stone]

I installed a Blue Seas ACR this past spring. I had specific reasons for the wire size I chose. I don't have a high demand system. My electrical requirements are small. I don't see the need for going overboard on wire size. It's expensive, the wires are hard to bend, the fittings are expensive. I discussed this with expert ABYC marine electricians. I chose #2 AWG for all the heavy wire and #4 AWG for the jumper. I don't have an electric windlass.

I documented the project on the forum. Go to page 34 for the wiring. http://www.capedory.org/board/viewtopic ... &start=495

Or you can read through the five part series on my website. Lots of pictures and details. Here is a link, I think, to the part with the ACR. https://farreachvoyages.net/2021/06/04/ ... #more-2091

Good luck.

[John Ring]

Hi Jake,

If it's the black ground wire that comes off the small tab connectors on the ACR and gets a 1amp fuse, then it's not carrying much current. I think I went with about a 14 or 16g wire, as seen here in my installation. It's really odd to see a fuse on a ground wire, but that's what the instructions call for.

The larger gauge wires you describe that actually carry some current sound about right.

That ACR is one of the best things I've ever put on my boat.

Best,
John Ring
CD36 Tiara

[Jim Walsh]

For those who lack a basic understanding of what an ACR is and does. https://www.bluesea.com/resources/1366

[John Stone]

Hi Jake,

If it's the black ground wire that comes off the small tab connectors on the ACR and gets a 1amp fuse, then it's not carrying much current. I think I went with about a 14 or 16g wire, as seen here in my installation. It's really odd to see a fuse on a ground wire, but that's what the instructions call for.

The larger gauge wires you describe that actually carry some current sound about right.

That ACR is one of the best things I've ever put on my boat.

Best,
John Ring
CD36 Tiara

I agree with John Ring. I think the only neg wire that runs from my ACR goes to the main neg bus and it has a 1 amp fuse. Very small wire. Probably 12 or 14 AWG. I can check tomorrow.

[Senorjacob]

Thanks, guys. I went with 14awg. Haven’t yet wired it all up but I’m close. Problem is while I was doing this my Balmar battery meter suddenly stopped working an I have no idea why. As I was changing up the wires I must have changed something and now the balmar doesn’t see the shunt anymore. Tech support didn’t have any answers. I checked and rechecked the wires and it’s hooked up correctly I think. My next step will be to check the deutsch-style connectors on the com cable. Might’ve pulled one of them out by accident.

All of it is fun.

Jake

[John Ring]

The Blue Sea ACR is great, but there may be one concern that involves shore power charging. I always wondered if my ACR sensed the 14.1v charging current coming in from the 110v shore power charger and connected the house & starter batteries together while my older "smart" shore power charger was trying to provide separate charging currents for each bank. Maybe it's just my nautical OCD kicking in?

Fortunately, Blue Sea has us covered with their P12 series of shore power chargers that sends a signal to the ACR telling it NOT to connect the two banks while the P12 is charging. (And yes, I'll be installing my new P12 over the next few weeks : )

Cheers,
John Ring (No, I don't work for Blue Sea Systems : )
CD36 Tiara
PS: 14.1v is correct for Tiara's Firefly carbon foam AGM batteries

[JD-MDR]

A few months ago I bought a new battery for my two bank system. I wanted to use the two older batteries for the house. I had the typical 1-2- both switch and a WM Prosport smart charger. The next day I could smell sulpher and the house batterys were overheating and low on water. Thats when I got the Blu- Seas ACR “add-a-battery” kit. I tossed the second house battery. Everything seemed to be working fine. Last week I noticed the house battery was down below 10V. I knew it was time (4 years) to replace them. My point is. The ACR worked perfectly. The house bank was low but the starter was up above 13V. Now I have a new starter and two new house batteries. It seems to be working perfectly. I also installed the FlowRite battery watering system that Jim W recommended. And that is great I was having to pull the batteries to check water levels. Not any more

[tjr818]

I bought one for our boat and never installed it, it won't be needed now because we are going from Diesel to 48 Volt Electric drive.
$30 plus postage if any on wants one.

ACR.jpg

[jbenagh]

I agree with John Ring; this is a fairily low amperage circuit. All you need is to provide enough wire to cover about 3x the 1A current; for couple foot run you are great with 12-16ga wire. Do ensure the fuse is near the controller, NOT at the battery, unless all are within 7in. It's fused near the ACR controller since a controller failure could dump current into the ground and thus the wire and thus a fire.
Jeff

[JD-MDR]

I agree with John Ring; this is a fairily low amperage circuit. All you need is to provide enough wire to cover about 3x the 1A current; for couple foot run you are great with 12-16ga wire. Do ensure the fuse is near the controller, NOT at the battery, unless all are within 7in. It's fused near the ACR controller since a controller failure could dump current into the ground and thus the wire and thus a fire.
Jeff

Hi Jeff, are you saying the fuses should be on the ACR controller like I had it in the first photo. I thought that is what the tech at the shop told me but I didn't think he was right so I put them on the batteries.

[jbenagh]

JD,
I was talking about the ground wire, it should be fused within 7 inches of the ACR. Your battery wires are correctly fused at the battery like in your second picture.
Jeff

[JD-MDR]

Thank you Jeff. I guess I will put a inline fuse on that ground wire.I have it going to the neg side of the fuse block.

I worked too hard the last two weeks I was too tired to go sailing and just layed around on the boat. Ive been trying to find little things to do but I seem to be pretty well caught up and ready to set sail except for haul out in December. I did put a louvered vent on the hanging locker door. I noticed the clothes I brought down had a bad smell. I think I will also get some Damperin or something like that.

[Senorjacob]

JD,
I was talking about the ground wire, it should be fused within 7 inches of the ACR. Your battery wires are correctly fused at the battery like in your second picture.
Jeff

I fused the ground wire way down by the negative bus. After reading your post and looking back over the instructions it does look like the 1 Amp fuse should be closer to the ACR. I guess I’ll redo that.

Thanks.
Jake