R-21EC's ProMariner charger and battery relay box

[baz]

Subject: R-21EC's ProMariner charger and battery relay box

I'm wanting to understand the actions of the engine battery charger's black relay box and Thermal Circuit breaker.

Here are the photos of the relay box and Thermal circuit breaker on my R-21EC.

The reason I'm posting is that I've had the 'slow flash' green LED twice now and have had discussion with Kenny Marrs about this.

The 'slow flash' I've had was because I had left my boat at the dock/slip on two occasions without shore power connected to the ProMariner battery charger.

1) For one week without shore power and main battery switch in helm electrical cabinet/locker in the ON position and Refer set at #3.

2) For two days without shore power and main battery switch in helm electrical cabinet/locker in the ON position and Refer set to #0 (i.e., OFF)

Each time I've returned to the boat under conditions 1) & 2) at my dock the black relay box has shown the 'slow flash' green LED. According to the label on the relay box the 'slow flash' is not an indication one or both batteries are at or below 9.5 volts. It some other cause which I don't really understand.

My understanding is that if I see the 'slow flash' then the running engine cannot charge the house battery. This was evident as when running the engine under conditions 1) & 2) none of my 12v accessories (such as Chart plotter and cabin lights) would light up.

My understanding from Kenny is that the black box relay is a safety device that stops the engine/alternator from charging the house battery if it's below a certain voltage. Why is this ? I would think the engine/alternator should charge the house battery if its voltage level is low.... but dunno if this can cause a safety issue. Can others here explain the purpose of the black box relay operations ?

Also, anyone care to explain what the Thermal Circuit breaker is all about ?

The reason I had situations 1) & 2) was because I was waiting for my Marino 12' shore power cable to arrive. My Marina insists my R-21EC use a standard shore power cable connected to the dock's power pedestal. Now that I have this shore power cable the boat is left connected to shore power and I hope never to experience situations 1) & 2) again.

I also, per Kenny's advice will always have the main battery switch in the OFF position to ensure no 12v accessories are drawing power when on shore power and boat left there for a while. Just the batteries will be kept charged. Of course Refer will not have food items but may have bottled water and soft drinks left inside. This means unfortunately I can no longer leave my Caframo Dehumidifier running in the cabin via a 150 watt inverter connected to the 12v cig lighter receptacle.

Any insights to the above enquiry are welcomed. Thanks..... 🙂

 

[SGIDAVE]

Subject: R-21EC's ProMariner charger and battery relay box

I'm wanting to understand the actions of the engine battery charger's black relay box and Thermal Circuit breaker.

The reason I'm posting is that I've had the 'slow flash' green LED twice now and have had discussion with Kenny Marrs about this.

The 'slow flash' I've had was because I had left my boat at the dock/slip on two occasions without shore power connected to the ProMariner battery charger.

1) For one week without shore power and main battery switch in helm electrical cabinet/locker in the ON position and Refer set at #3.

2) For two days without shore power and main battery switch in helm electrical cabinet/locker in the ON position and Refer set to #0 (i.e., OFF)

Each time I've returned to the boat under conditions 1) & 2) at my dock the black relay box has shown the 'slow flash' green LED. According to the label on the relay box the 'slow flash' is not an indication one or both batteries are at or below 9.5 volts. It some other cause which I don't really understand.

My understanding is that if I see the 'slow flash' then the running engine cannot charge the house battery. This was evident as when running the engine under conditions 1) & 2) none of my 12v accessories (such as Chart plotter and cabin lights) would light up.

My understanding from Kenny is that the black box relay is a safety device that stops the engine/alternator from charging the house battery if it's below a certain voltage. Why is this ? I would think the engine/alternator should charge the house battery if its voltage level is low.... but dunno if this can cause a safety issue. Can others here explain the purpose of the black box relay operations ?

Also, anyone care to explain what the Thermal Circuit breaker is all about ?

The reason I had situations 1) & 2) was because I was waiting for my Marino 12' shore power cable to arrive. My Marina insists my R-21EC use a standard shore power cable connected to the dock's power pedestal. Now that I have this shore power cable the boat is left connected to shore power and I hope never to experience situations 1) & 2) again.

I also, per Kenny's advice will always have the main battery switch in the OFF position to ensure no 12v accessories are drawing power when on shore power and boat left there for a while. Just the batteries will be kept charged. Of course Refer will not have food items but may have bottled water and soft drinks left inside. This means unfortunately I can no longer leave my Caframo Dehumidifier running in the cabin via a 150 watt inverter connected to the 12v cig lighter receptacle.

Any insights to the above enquiry are welcomed. Thanks..... 🙂

Hello Barry,

The "battery relay box" is called an ACR (Automatic Charging Relay). If ANY lights (LED) flash on the ACR, then it a will not combine the battery banks. The purpose of your ACR is to receive the charge from the Alternator...let it charge the START battery, then pass the charge current through to the HOUSE battery by means of creating a PARALLEL circuit. After you stop the engine, the ACR will OPEN when it detects a prescribed drop in voltage of the start battery thus isolating the two batteries. You can run down the HOUSE but not the START with this nifty devise. Further details are found on Blue Sea website here. Note the column on the left of the webpage shows downloads such as a diagnostic flow chart, installation instructions, etc to help you understand it better. Didn't your R25 have several ACRs?

Whether the blink is SLOW or FAST, your batteries will remain "isolated" until the cause for said isolation is remedied.
I suspect your cause for forced isolation is house battery voltage less than 9.5VDC. The ACR will not automatically close and cause the DEAD house battery to receive a charge because it's built-in safety circuitry requires it to recognize there is a 12VDC battery connected. For safety, the ACR doesn't want to errantly pass charging current to something else, like an overcharged 6V battery, etc.

The 100A breaker in your pick is the overcurrent protection for the large red wire running to the house fuse block under the throttle/shifter. At the wire's termination, it passes through the large Blue Sea ON/OFF switch to which Kenny refers. When leaving the boat, you MUST shut off DC power to the house or risk a DEAD house battery - as you already know from your 2X experience. You can accomplish this by using the switch in the house or the breaker in the picture. The little group 24 battery cannot operate the fridge for long before going dead. And there are other parasitic loads to include the stereo memory, etc. [FYI - you should also ensure your THRUSTER switch is OFF when your boat is unattended as well since there are MANY reports of the thruster turning on for no reason]

dave

 

[baz]

Thanks Dave.... where would all of us R-21EC owners be without you at our side.... Thanks. 🙂