Blue Sea Auto Charging Relay question

[Capt’nKarl]

2009 RT 21-EC with 3ym30 Yanmar engine. 1 starter and 1 house battery. There are 2 Blue Sea Auto Charging Relays. This is the first time I’ve noticed this in the 6 years I’ve had the boat. The relay LED light on the starboard side is always on. The relay LED light on on the port side flashes. This is happening regardless of whether the boat is plugged into shore power or not. There doesn’t seem to be anything wrong, all electronics are working normally and this might be normal. Can anyone tell me why one light is solid and the other light flashes?
Thank you,
Karl

 

[NorthernFocus]

Not sure why you have two relays with only two batteries. Did someone remove a third battery at some point in the past? Are there cables connected to both sides of both relays? The LED on continuously indicates the relay is closed thus connecting the two batteries. That should be the normal state when the engine is running. The flashing LED indicates low voltage on one side or the other of the relay. Which would be the case if there is no batter connected to one side of that relay. Sounds like you have one relay that is only connected to one battery.

 

[Osprey]

A solid green is present when the battery voltage is at 13.0V or more for at least 90 seconds. Less than 13.0V the light should be off. A flashing green indicates that the ACR is in a lockout state. One cause of lockout occurs if the battery voltage is at 9.5V or less. Another is if there is a positive voltage present at the ACR's Start isolation terminal. You will find 3 spade terminal on one end of the ACR, ground, isolation and remote LED. On my tug only the ground spade is used.

Take careful note of the comment above by NorthernFocus with respect to number of batteries. Could be that the flashing ACR is looking for a battery that is not there, so less than 9.5V for that connection.

 

[Capt’nKarl]

Gentlemen
thank you for the responses. It now makes sense. The original equipment had a 12 Volt air conditioner and 2 additional house batteries which I have removed. Sounds like I only need one of the relays. Now, do I need to disconnect the flashing relay?
Thanks again,
Karl

 

[Osprey]

I do wonder a bit about exactly what the present connections are like, but an easy way to take the flashing ACR out of service is to simply disconnect the ground lead from that ACR. The female part of the connection (on the end of the wire) can be pulled free from the ACR mounted male part.

 

[NorthernFocus]

Gentlemen
thank you for the responses. It now makes sense. The original equipment had a 12 Volt air conditioner and 2 additional house batteries which I have removed. Sounds like I only need one of the relays. Now, do I need to disconnect the flashing relay?

It's not hurting anything. One can argue that having extraneous electrical equipment on a boat is not a great thing. If for no other reason than to avoid confusion when troubleshooting problems etc. as demonstrated by this thread 😉