Help with battery use.

[Notlongnow]

Hi everyone. Long time reader here with a first post, looking for some advice.

I’ve recently bought a 42 foot Savage Oceanic yacht. I’ve done a lot of sailing in the past but in smaller boats, so this is a step up for me in the complexity of the electrical system on board. I’m going through the process of trying to understand the layout and to map out the wiring, but I have a few questions about the battery set-up and use of the switches. The batteries on board are fairly old I think (look like 5+ years) and aren’t maintaining much charge (11-12V) so before I replace them all I want to make sure I know what’s going on so that I don’t damage a new set.

After hunting around in the engine compartment I’ve prepared the wiring diagram attached of the battery and switch set-up. I have lots of questions and would be grateful if anyone can help me with any of them…

- which of the switches on the 1/2/B should I use for starting and running the engine? The contour battery switch turns all of the auxiliaries on or off but the engine start is controlled only by the 1/2/B switch. I’ve been starting and running the engine on B, but would this mean I’m not then using the alternator to charge the batteries? (I need to check the alternator wiring, but I’m assuming it is back to the starter). Should I instead be selecting 1 or 2 to direct charge back to either the house or start batteries? The engine starts using any of 1, 2 or B, so I’m a bit confused over how this all works given the starter motor is connected only to B.

- the house batteries are 125Ah AGM’s and the start battery is a standard wet battery Century Marine. They’re all located directly next to the engine where it gets pretty hot, and the AGM’s are a bit swollen and out of shape. When I replace the AGM’s I’m wondering whether I should just use standard FLA on the basis that they will handle the heat better and the AGM’s aren’t worth the premium in this location?

- the shore power runs AC through a charger located at the nav station instrument panel. The battery monitor shows charge current is being directed to the batteries when the charger is on. I haven’t mapped this yet, but will that likely be wired through to the PV Charge Controller in the engine compartment?

Thanks for anyone’s help. Yes, I’ve read lots of past threads and it is slowly coming together, but I’m hoping asking these questions will jump start things a bit, if you’ll pardon the poor pun.

[LittleWing77]

Swollen batteries are bombs. GET THEM OFF YOUR BOAT NOW.

Batteries should NEVER be in the engine compartment! You need to find an alternate ventilated area where they can be secured near, but not in, your engine compartment and yet be readily accessible.

LittleWing77

[Kelkara]

The way you have drawn your wirign diagram (if I've read it right ... the wiring of the VSR is a bit unclear especially how it joins to the second switch, and what you called the -ve bus looks like a shunt) ...

Battery #2 is your start battery, and battery #1 is your house battery. You should leave the 1/2/B switch on position "2" at all times (or "off" if you want it off), unless your start battery is dead in which case you switch to position "1" to use the house bank to start the engine. Position "B" is mostly redundant since you have a VSR that combines the batteries for charging, you can still use position "B" for charging if the VSR fails, or if both batteries are almost dead and you want to parallel them for a last gasp attempt to start the engine.

[edit: it seems you are a bit unclear on how the 1/2/B switch works ... it selects which battery is connected to the engine (and windlass): "off"=none "1"=#1 house battery, "2"=#2 start battery or "B"=both in parallel. You have a dedicated start battery (#2) so you should be using that normally. Traditionally you would use the "B" position so you can charge both battery banks at the same time, but your VSR should take care of that for you automatically.]





You are mixing AGM and flooded batteries in your sustem ... that means that one of them may not be getting the proper charging voltages. I shall leave it to others to comment on whether that might be part of the cause of your batteries demise.



While you are tracing out the wiring of your system ... pay attention to where you ought to have fuses, I don't see any in your picture.

[smac999]

You need to open the vsr and 2nd switch. I’m betting those wires are joined inside. Ie I bet the solar is directly connected to house. Using the vsr and house switch as jumpers.

If so the vsr is joined between both banks. So it will charge both batteries when engine is running.

So the small switch is the house switch. And the 1-2-all is the engine switch. And should anyways be left to the engine battery. Unless you have issues. This is assuming the vsr is working and charging the house. You’d have to test.

The 2 small wires leaving switch are Likly volt meter at panel. Probably also bilge pump.


It looks like you have drawn something wrong. As the 2wires in picture to acr are coming from the engine switch. (Probanly house and engine battery). Solar will simply join onto the house wire. Your drawing shows one acr wire from the house switch. Which does not match photo


You are missing a lot of fuses..,.

[Stu Jackson]

There is no B on the 1-2-B switch for wiring. It should be C, for combined, only to be used when charging.


Here are some links for you to review. They come from my collection in here:


Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html


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OEM 1-2-B Switch Wiring History http://c34.org/bbs/index.php/topic,4....html#msg30101

1-2-B Considerations (New 2020 - Rod finally got around to diagramming what I had done in the above link in 2009 )
https://marinehowto.com/1-2-both-bat...onsiderations/

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowner...d.php?t=137615

This is a newer primer for boat system wiring design with a thorough diagram: Building a Good Foundation (October 2016)
http://forums.sailboatowners.com/ind.../#post-1332240

[Notlongnow]

All,
Thanks very much for your responses and advice. Exactly what I was looking for.
I have a lot to learn and do!

[Sailon1]

Another consideration as far as battery replacement: new batteries may likely require a new, more powerful charger (3 bank, 4 bank, etc) which may also require new, heavier gauge wiring, fuses, connectors, crimping tool, and more. My “simple” battery upgrade turned into quite a project. Surprise Surprise. Good news is that the “new” charger (now 3 years old)and 100 ah AGM bats are holding up very well.

[Flatswing]

Originally Posted by LittleWing77

Swollen batteries are bombs. GET THEM OFF YOUR BOAT NOW.

Batteries should NEVER be in the engine compartment! You need to find an alternate ventilated area where they can be secured near, but not in, your engine compartment and yet be readily accessible.

LittleWing77

Perhaps a little hyperbole here.
The AGM’s are swollen because they are failing not because of heat in the ER. Definitely replace them. If the chemistry of all your batteries is similar (go to the manufacturer’s web site for charge, absorb & float settings) it can help make your charging set up easier.

Certainly having LA batteries in ER with gas engines is frowned on. But realize that 90% of diesel powered boats over the past 40 yrs have their batteries located in the Engine compartment!

[guyrj33]

Originally Posted by Stu Jackson

There is no B on the 1-2-B switch for wiring. It should be C, for combined, only to be used when charging.

I've always understood the C terminal on the back of the 1-2-B switch to be 'Common'. What it is is the output terminal for the switch which can be connected to Off, 1, 2, or Both.

I know this is a small point and my comment may appear petty, but with the obvious problems many have understanding the electrical systems on their boats I think we need to be as clear and consistent as possible.

Also in my opinion batteries in the engine compartment can be OK, it depends on the installation. It might be better to say batteries have longer life when prevented from overheating.

[Sailon1]

Thank for the link (the Mainsail link is not working).

[Joli]

The house bank is wired incorrectly. Only battery #1 (left most in your drawing) is receiving a full charge. The positive cable from your battery switch should be going to the positive post of house bank battery #3 (right most battery).