Battery Switch Replacement - ACR?

[Timccarpenter]

I've got a simple battery system for our 27' Tartan sailboat. Two 24 group deep cycle batteries and the old style OFF - 1 - Both - 2 Switch. I've realized recently that our one battery is not getting any charge from the Alternator when the engine is running. It seems to be the switch that is faulty. I checked and cleaned the connections on the cable and the continuity checked out fine. The switch is at least 20 years old.

I'm looking at replacing the switch but am finding, in addition to the traditional old switches, those that are simply 'ON' and 'ALL' with an Automatic Charging Relay (ACR). It seems these setups help prevent issues with draining batteries by not switching to 1 or 2 under sail after shutting off the engine. However, does it have limitations? What if your starting battery fails and you need to start with the house battery? Does switching to 'ALL' really work or does that bad battery draw down the good one?

Simplest solution is to replace the switch as is. However, I don't want to make a mistake by improving the setup if there is a significant advantage.

I appreciate the input/guidance

[Wotname]

A 'OFF - 1 - Both - 2 Switch' is fool proof as long as the operator is not a fool. Most of us (including me) becomes foolish occasionally and when that happens, a 'OFF - 1 - Both - 2 Switch' is not ideal.

An ACR is fool proof as long as the electronic 'brain' works. An ACR has a manual override function that you use when you wish to parallel the batteries.

I used to prefer the 'OFF - 1 - Both - 2' switch, now I prefer an ACR.

Alternator to Start Battery, ACR between Start and House Battery.

Start battery is always fully charged (100% SOC) without any input from you. House battery SOC varies up and down with use. If Start battery fails, use the manual override function of the ACR to parallel Start and House.

[Johan Leopard51]

Originally Posted by Wotname

A 'OFF - 1 - Both - 2 Switch' is fool proof as long as the operator is not a fool. Most of us (including me) becomes foolish occasionally and when that happens, a 'OFF - 1 - Both - 2 Switch' is not ideal.

An ACR is fool proof as long as the electronic 'brain' works. An ACR has a manual override function that you use when you wish to parallel the batteries.

I used to prefer the 'OFF - 1 - Both - 2' switch, now I prefer an ACR.

Alternator to Start Battery, ACR between Start and House Battery.

Start battery is always fully charged (100% SOC) without any input from you. House battery SOC varies up and down with use. If Start battery fails, use the manual override function of the ACR to parallel Start and House.

An ACR should (our Blue Sea does) work both ways automatically. Ours connects the two batterie when the voltage of either one is 13.1 or 13.2 for more than two minutes.

[Wotname]

Originally Posted by Johan Leopard51

An ACR should (our Blue Sea does) work both ways automatically. Ours connects the two batterie when the voltage of either one is 13.1 or 13.2 for more than two minutes.

Yes, this is correct. My previous comment refers to how to parallel the batteries when there is no charging source present. This is a manual function.

[Timccarpenter]

I'm also puzzled by why the one battery that has not been connecting to the alternator (due to the faulty switch) but is connected to a xantrex battery charger is only showing 12.4v. With the charger in float mode, shouldn't I expect that battery to be above 13v? The other battery (that is successfully connecting to the alternator through the switch) is also showing less than 13v...closer to 12.7v

The charger is 20 years old...is this failing too?

[tombeau]

We replaced an ACR with a 1-all-2-off. ACR would only charge one battery, and the other went flat. Called the mechanic where we bought the boat, and he said they failed frequently and that people just replaced them with the tried and true manual switch. I think if you have one that works, it is good. If it doesn't work, not so good.

[Johan Leopard51]

Originally Posted by tombeau

We replaced an ACR with a 1-all-2-off. ACR would only charge one battery, and the other went flat. Called the mechanic where we bought the boat, and he said they failed frequently and that people just replaced them with the tried and true manual switch. I think if you have one that works, it is good. If it doesn't work, not so good.

I replaced both ACR that shipped with the 2014 vessel and on my last trip one was again not charging to house when I measure it should be. There is a Victron (can’t remember name but basically it does same thing, combine the two when one of the two is very happy). I’m slowly going to change everything to Victron.

Risk is neither of the two are happy and you must help starter battery NOW.

For boosting a starter battery on even an enormous diesel motor and much else like having a portable 12V source for testing all the stuff we have and you don’t know whether it is fubar or wiring is suspect or switch is suspect, there are nice Lithium high discharge battery packs. It charges off USB, I leave mine almost always charging ready to use. Sort of size of half the height of a shoe box, can help jump start, and it has USB outlet ports for letting people charge their stuff wherever they are on yacht for casual use. Definitely a worthwhile addition. You can even jump-start another yacht in trouble paddling over with your brick instead of 8 meter soldering cables tied up together