automatic charge relay

[fallard]

Looking for verification of ACR wiring in my recently-acquired 2019 R-27. The 2 ACRs in the port cockpit locker have a common wire that is routed to a negative terminal of the ganged house batteries, but it is not connected. The Blue Sea site indicated that this wire might be the connection to the "negative bus bar", to which the battery negatives would be connected, according to the R-19 Owners Manual. It looks like I should just connect it to the battery negative. (The previous owner apparently replaced the batteries within the past year, so it may be an oversight).

 

[Lake Effect]

Did you find the answer? Bringing this to the front.

 

[fallard]

Did you find the answer? Bringing this to the front.

I did not get a reply to my post, so I did connect the common wire from the 2 ACRs to the negative terminal of the ganged house batteries (which I understood was connected to the "negative bus bar, per the R27 owners manual wiring diagram.) Previously, I was uncomfortable with the voltage readings on the house batteries, but the battery voltages now look reasonable. I believe the problem is solved, but being new to the boat, was looking for confirmation of my assessment.

 

[Submariner]

Looking for verification of ACR wiring in my recently-acquired 2019 R-27. The 2 ACRs in the port cockpit locker have a common wire that is routed to a negative terminal of the ganged house batteries, but it is not connected. The Blue Sea site indicated that this wire might be the connection to the "negative bus bar", to which the battery negatives would be connected, according to the R-19 Owners Manual. It looks like I should just connect it to the battery negative. (The previous owner apparently replaced the batteries within the past year, so it may be an oversight).

The ACR sits between two battery banks on the positive wire. Engine and House, House and Thruster, for example. Being a 2019, yours probably are engine to Hosue, and engine to thruster. Because the ACR bridges the positive side only, and it needs a voltage reading to function, that's the yellow wire (needed to complete the electrical circuit to take a voltage reading).

The ACR's are just automatic parallel switches. When they see a charge voltage (engine running, solar charging, or the battery charger is turned on), voltage will go up to 13+ volts. The ACR's will see that higher voltage and will close, paralleling the battery banks together. When the charge voltage goes away (voltage drops to less than 13 volts), the ACR will sense that, and will open/isolate the battery banks.

If the yellow wire is disconnected (easy to knock off, if you store equipment in the port lazarette), then the ACR will never close/parellal the banks together. This means you won't get any engine charging of the house or thruster bank when underway.

This is a great video that talks all about the electrical system and how it works on your boat. I talk specifically all about the ACR's at timestamp 19:15.

Electrical Overview of a Ranger Tug R27-OB

 

[Lake Effect]

Thank you!

 

[fallard]

Thank you!

The ACR sits between two battery banks on the positive wire. Engine and House, House and Thruster, for example. Being a 2019, yours probably are engine to Hosue, and engine to thruster. Because the ACR bridges the positive side only, and it needs a voltage reading to function, that's the yellow wire (needed to complete the electrical circuit to take a voltage reading).

The ACR's are just automatic parallel switches. When they see a charge voltage (engine running, solar charging, or the battery charger is turned on), voltage will go up to 13+ volts. The ACR's will see that higher voltage and will close, paralleling the battery banks together. When the charge voltage goes away (voltage drops to less than 13 volts), the ACR will sense that, and will open/isolate the battery banks.

If the yellow wire is disconnected (easy to knock off, if you store equipment in the port lazarette), then the ACR will never close/parellal the banks together. This means you won't get any engine charging of the house or thruster bank when underway.

This is a great video that talks all about the electrical system and how it works on your boat. I talk specifically all about the ACR's at timestamp 19:15.

Electrical Overview of a Ranger Tug R27-OB

Thanks for the video.

 

[mcmspark]

This is greatly appreciated! However I cannot seem to locate the engine to house acr.

My port lazarette is different. There s only the acr for the house to thruster.

In the starboard lazarette the engine battery has a cable labeled to go to the House ACR but I fail to trace it. The ACR shown here is actually connected to the thruster battery.

The engine battery to ACR is labled

Then it disappears behind a bulkhead

And comes out ahead of the hydraulics into a rats nest, where I loose it.

What I am doing now is all planning for a Lithium upgrade. I have been tracing and documenting what I find. So far it does not seem like there is consistent placement of components.

I have a 2021 RT27 Not LE but with AC and a 3000w sinewave inverter. The inverter is under the stove, and until I found it I thought I had the 2000w version.

The plan involves replacing the ACR’s with DC to DC chargers and properly fusing the banks.

I plan to start with a solar upgrade and them move o to the Li upgrade.

Anyone else find this ACR in a weird place?

 

[Submariner]

I have a 2021 RT27 Not LE but with AC and a 3000w sinewave inverter. The inverter is under the stove, and until I found it I thought I had the 2000w version.

The plan involves replacing the ACR’s with DC to DC chargers and properly fusing the banks.

I plan to start with a solar upgrade and them move o to the Li upgrade.

Anyone else find this ACR in a weird place?

You have an RT-27 LE, 2021 model, without LFP. That's how they were sold back then. The LE came with dock-side air conditioning, or LFP as an optional upgrade from the factory (it was about $12k to upgrade). The LE's came with an air conditioner and a 3000 watt inverter. The NW editions came with a 2000 watt inverter and a Webasto diesel heater (and no option for an upgrade to LFP).

I have it fully documented on how to convert a RT27-OB to LFP published on our website, with several videos on YouTube that go over what is involved.

Upgrading a RT27-OB to LFP

House Battery-Lithium | LetsGoChannelSurfing

www.letsgochannelsurfing.com

 

[Submariner]

The plan involves replacing the ACR’s with DC to DC chargers and properly fusing the banks.

You'll also need bus bars installed for positive and negative as charging and electrical loads can't directly connect to the LFP battery posts. They need to be relocated to the bus bars. A T-Class fuse is required to protect the boat from the battery bank. A battery monitor must be installed with a physical guage (required by ABYC). A guage is necessary as bluetooth app's can't sound alarms on the boat. The solar charger and battery charger also need to be upgraded to support LFP. If there's a kicker, it has an alternator and must be moved to the engine or thruster battery.

I wish it were easier to convert an R27-OB. I've done it twice. Once on Channel Surfing in February 2022 and again on a red 2022 RT27-OB in March 2023. It's great once converted, but it's work and $$ to convert the boat.

We Upgraded to Lithium - What it took to get there