Battery switch with shore power breaker

[keelsidedown]

I'm looking for a main house battery switch (bank 1, bank 2, both, off) that includes a shore power breaker (puts the switch in off mode in the absence of shore power and is selectable for that function so that the switch functions like a normal batter switch at sea).

Anyone know of anything like that?

I'm tired of the marina's shitty power running down my batteries.


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[Stu Jackson]

Haven't heard of one. A friend added a relay to perform that function.

Why do you leave the switch on when you're not there?

[keelsidedown]

Originally Posted by Stu Jackson

Haven't heard of one. A friend added a relay to perform that function.

Why do you leave the switch on when you're not there?

Part time liveaboard, but have a day job that requires just enough away time that the batteries will get run down in an outage. I will be replacing both house battery banks in the very near future because of that.

Now that I think about it, I'd also like to have a configurable breaker (cutout set to, say, 50% of the battery bank's capacity) for the renewable input side (wind/solar) as well. The thing I've learned over the years of battery ownership is that if you can avoid drawling below 50%, the life and performance of the battery will be much better.


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[Andina Marie]

I did the equivalent by disconnecting my house bank when on shore power and replacing it with a cheap Walmart battery. With shore power the battery only needed enough capacity to supply intermittent loads and provide a destination for the shore power charger. That way the at-dock loads like water pump etc., don't "short cycle" my main bank and no big deal if it doesn't last long.

When under way, or for monthly charge top up, a simple on/off switch connects the main bank back on.

[Roy M]

So, the issue is that crappy shorepower goes out, runs the house bank down and wrecks the batteries, not that it ruins anything in the refrigerator/freezer or shuts down any other vital systems, beyond your bilge pump, possibly, alarm system, or makes your computer log off.

Andina Marie has the basic solution. Another is to significantly increase your house bank size to that which will bring your discharge level down only to 50%. An additional safeguard would be to add solar panels to the increased house bank to give you greater energy independence.

[motaman9]

Is there a Schottky or "blocking" diode in your electrical circuit between the charger and the batteries? The addition of one of these should eliminate the "reverse drain" of your batteries. They act like a "one way valve" for the current preventing discharge by panels or low voltage supply. There is a small voltage drop, but worth it to preserve your batteries.

Many, or most, modern charge controllers utilize reverse current blocking through the use of semiconductors or relays that can prevent the draining of the batteries.


www.learntoliveaboard.com

[Terra Nova]

Originally Posted by keelsidedown

...I'm tired of the marina's shitty power running down my batteries...

It's not the shitty marina power but your shitty electrical system. There's no way the marina power is flattening your batteries.

[moseriw]

Look at the attached wiring diagram...

Mention: Earth goes to the galvanic isolation system (the sacrifying anode)
and Battery minus is also connected to the galvanic isolation system.

And: the 230V or 110V System can be connected via Earth (N eutral) to the
Battery Minus... it will not affect your system.

In fact: if you need a Battery Switch with shore power breaker your point of view and/or your sysem is terribly misconfigurated ;-)

[moseriw]

about: Is there a Schottky or "blocking" diode

BE aware of this! Do not believe wathever the industrie says. No Schottky Diodes! every Diode will cost you 0,4 - 0,5 V!

Believe me I learned it the expensive way!

You can check your system with my 4 Battery setup which is well working!
see attached wiring diagram.

[MarkSF]

What should happen, if the shore power goes out, is very little. Normally the only load on the batteries would be whatever is left on. If that's just the bilge pump, the batteries should last for months. If you have a 12V fridge, they should still last a lot longer than a day.

The real question is why your batteries rapidly go flat when they aren't being charged. You need to fix this problem, not try to invent a new kind of breaker.

Any decent charger will not flatten the batteries if the mains power is cut off. How is this different from a boat that's cruising away from the dock?

If you described your setup in a bit more detail, that would help. Type & number of batteries, type of charger, what's operating on the batteries, and so on.

My suspicion, though, is that your batteries are dead and won't hold a charge.

[motaman9]

Originally Posted by moseriw

about: Is there a Schottky or "blocking" diode

BE aware of this! Do not believe wathever the industrie says. No Schottky Diodes! every Diode will cost you 0,4 - 0,5 V!

Believe me I learned it the expensive way!

You can check your system with my 4 Battery setup which is well working!
see attached wiring diagram.

I noticed there is a "Victron Argo Diode Battery Isolator" in your diagram...which if I'm not mistaken contain a high efficiency Schottky diode......


www.learntoliveaboard.com

[HopCar]

I'm with Mark on this one. Your batteries should carry your power needs for a day or two without charging.
If the power is off in the marina frequently or for long periods of time, start looking for a new marina.

[exMaggieDrum]

I'm also confused by OP on the situation as described. After rereading it and the other posts I am guessing the real problem is that battery powered circuits on board the boat are "draining" the batteries when the shore power goes off - I assume because the shore power AC to DC battery charger quits. So basically the batteries aren't really powering anything in a significant way since they have very little capacity.

Turning off the shore power should have zip to do with the batteries running down, or at least, I have never seen a situation where that is the case. So if the shore power goes off it should be no different than if you turned off the shore power breaker manually.

You need to get good, adequately sized batteries that can handle X hours of no charging with whatever 12v loads you need to leave on in your absence (or even if you are there really). And just turn off the batteries at the battery switch when you leave. Turning off the shore power breaker should make no difference. May be I am missing something here?

[motaman9]

I think Mark's estimation was also very likely correct. Although, the root cause of the batteries being bad could be the consistent deep draining, which, if you just replace the batteries you are probably just buying time until it happens again unless you make sure your system is correct.


www.learntoliveaboard.com

[moseriw]

Originally Posted by motaman9

I noticed there is a "Victron Argo Diode Battery Isolator" in your diagram...which if I'm not mistaken contain a high efficiency Schottky diode......


www.learntoliveaboard.com

Yes Battery combiners! This is OK the battery Isolators on the charging side where the problem! but now it is OK and I have even with the combiners 14,2V and 13,8V without charging.