Schematic: tentative plan for new ignition/charging wiring

[rigspelt]

UPDATED 14 March 2009.
Our old A4's present (virtually original) ignition/charging schematic is here: http://www.moyermarine.com/forums/showthread.php?t=2685. I ripped out all the old wiring from this 27' sailboat. My tentative plan for rewiring is shown in the attached diagram. Any thoughts?

Caution: I am not an electrical engineer, just a boater. Seek professional electrical advice before modifying your boat.

Changes and my thinking:
1. Separate house and engine start circuits, one dedicated to each of the two batteries.
2. Both batteries exactly the same and to be purchased at same time (group 24 batteries with mixed CCA and deep cycle characteristics: like Nautilus Dual).
3. Blue Sea ACR 7610 to automatically combine the batteries for charging when the engine start battery is charged.
4. Blue Sea Combiner switch 5511e in combination kit 7650 to simpify battery switching operation for the crew (one switch on/off), automated paralleling of the batteries through the ACR for charging only (not starting!).
5. Ignition key to simplify operation for the crew (same as a car).
6. Run alternator output through a short wire to the starter BATT post to reduce that wire run (eliminate panel ammeter).
7. Replace the ignition panel ammeter in the cockpit with a voltmeter.
8. Collect all ground and grounding wires in a bus or two, rather than various bolts on the engine and bulkheads.
9. Fuse the battery (+) output wires.
10. Install a modern DC panel for the house loads with voltmeter for the batteries, and ammeter for house loads or alternator output (use handheld clamp to measur currents on other circuits as required).
10. Install alarm buzzers for engine temp and oil pressure, in addition to gauges on the ignition panel.
11. Install a tachometer in the ignition panel.

I'm slowly starting to get more comfortable with the cable sizes and fuse specs for my particular setup. The cables will be 105C marine, and the lugs will be professionally installed with shrinkwrap.

DRAFT schematic UPDATED 14 March 2009:

[High Hopes]

Rigsy,

Changes and my thinking:
1. Separated house and engine start circuits, one dedicated to each of the two batteries.
>>> This removes redundancy, or at least makes switching to another battery a cable swapping procedure.

2. Both batteries exactly the same and purchased at same time (group 27 batteries with mixed CCA and deep cycle characteristics).
>>> Not sure this will matter. What did you have in mind?

3. Blue Sea ACR to automatically combine the batteries for charging when the engine start battery is charged.
>>> I hadn't seen this before. It looks like a great idea as it eliminates having to remember to work a battery switch and monitor charge times.

4. Blue Sea Combiner switch to simpify battery switching operation for the crew (one switch on/off).
>>> Does this defeat #3? Why not leave the ACR on all the time?

5. Ignition key to simplify operation for the crew (same as a car).

6. Run alternator output through a short wire to the starter BATT post to reduce that wire run.

7. Collect all ground and grounding wires in a bus or two, rather than various bolts on the engine and bulkheads.
>>> Be advised that some of these ground wires may be part of your lightning protection system and not part of your 12 volt system.

8. Fuse the battery (+) output wires and collect the (+) wires on a nearby bus instead of on the battery post (still thinking about fusing).
>>> Starter circuits are usually direct wired with short, thick wire runs. You probably won't want to drop the coin for a 150 AMP rated bus and the heavier wire needed to accommodate the longer runs. Unfused direct battery-to-starter runs are permitted. You can add a starter circuit fuse if you wish, but typically they are not used as the battery is usually putting out the max current it can anyway so there isn't that much extra current to be concerned about. A .05 ohm short would be needed to draw 250 amps and these are difficult to make.

9. Install a modern DC panel for the house loads with voltmeter for the batteries, and ammeter for house loads or alternator output (have not decided, could add second ammeter in the cockpit for the alternator output).
>>> For alternator measurement, you will need to run longer alternator wires to the cockpit (see #6). I like the idea of a house ammeter. Some argue that ammeters are passe. They are probably right, but I'm a nerd, so...

10. Replace the ignition panel ammeter in the cockpit for a voltmeter.
>>> How about a simple alt charge idiot light? Put the ammeter and voltmeter below by the Combiner switch.

11. Alarm buzzers for engine temp and oil pressure.
>>> Good idea. I am installing some so I can watch the sunsets instead of the gauges. I will be locating gauges below in the engine compartment. I will be using a truck marker light (big - round - RED) in the cockpit for a trouble indicator.

I really like the idea of the ACR and the Combiner switch. It is simple. You might want to prepare yourself for the possibilities of different failure modes - ACR opens, ACR shorts one battery to the other, one battery is completely dead (be it house or engine, weather you are motoring or not), etc. I can't help but think a battery switch would be useful in the event of a failure. Very clever work. Go for it!

[rigspelt]

Thanks Steve. Your questions:

Originally Posted by SteveMarkowski

Changes and my thinking:
1. Separated house and engine start circuits, one dedicated to each of the two batteries.
>>> This removes redundancy, or at least makes switching to another battery a cable swapping procedure.

Not with the Combiner switch/ACR pair, I don't think. Unless as you point out in your post the paralleling/switching components fail.

Originally Posted by SteveMarkowski

2. Both batteries exactly the same and purchased at same time (group 27 batteries with mixed CCA and deep cycle characteristics).
>>> Not sure this will matter. What did you have in mind?

Takes some of the worry out of paralleling the batteries if need be, simplifies dual charging issues. A4 does not need huge CCA, and I will not need major deep cycle house energy. Also, allows me to physically switch batteries in a pinch if the start battery goes bad.

Originally Posted by SteveMarkowski

3. Blue Sea ACR to automatically combine the batteries for charging when the engine start battery is charged.
>>> I hadn't seen this before. It looks like a great idea as it eliminates having to remember to work a battery switch and monitor charge times.
4. Blue Sea Combiner switch to simpify battery switching operation for the crew (one switch on/off).
>>> Does this defeat #3? Why not leave the ACR on all the time?

Blue Sea link to Combiner switch plus ACR: http://bluesea.com/category/2/productline/docs/329 UPDATED
Combiner switch: and http://bluesea.com/category/1/productline/3
ACR: http://bluesea.com/category/2/productline/overview/387

also see this interesting post -- lots to think about:
http://continuouswave.com/ubb/Forum6/HTML/001232.html

Originally Posted by SteveMarkowski

7. Collect all ground and grounding wires in a bus or two, rather than various bolts on the engine and bulkheads.
>>> Be advised that some of these ground wires may be part of your lightning protection system and not part of your 12 volt system.

Good point.

[High Hopes]

Rigsy,

I was scoping out ARC's last night. I think I am sold. Bea Sea says that their relays are spec'd for one million closures. I will order one of these.

I was trying to figure out how to wire a 1 2 battery switch as a backup to the ARC. I haven't figured it out yet.

I really like the idea of not having to worry about charging each battery. It is funny, I started from a gauge-intensive, monitor-every-point design perspective. Now I am thinking that I should simplify wherever I can.

I did come up with one idea. Why have an ON/OFF 12 volt power switch at all? It seems redundant to turn all the boat power toggle switches off and then turn the battery off. Cars don't have a battery switch. They have an engine switch, but you can turn the lights on all the time, even if you don't have a key.

Thanks for posting your ARC schematic. I am learning from it.

Steve

[rigspelt]

Originally Posted by SteveMarkowski

I was trying to figure out how to wire a 1 2 battery switch as a backup to the ARC. I haven't figured it out yet.

Try this link: http://bluesea.com/category/2/productline/docs/329.

Originally Posted by SteveMarkowski

I did come up with one idea. Why have an ON/OFF 12 volt power switch at all? It seems redundant to turn all the boat power toggle switches off and then turn the battery off. Cars don't have a battery switch. They have an engine switch, but you can turn the lights on all the time, even if you don't have a key.

Interesting question. I will use one because I like the manual control. Calder (p. 37) says a battery selector/isolation switch is used to isolate a cranking battery when charging is finished, but the ACR would, as you say, play that a role in preferrentially maintaining the starting battery as long as it is working properly. I like the idea of being able to disconnect all downstream circuits from the battery to prevent either battery drain (disconnect engine battery when engine not in use at anchor, or prevent banks from draining from open circuits when the boat is unattended), or to reduce risk of fire in an unattended boat.

Originally Posted by SteveMarkowski

Thanks for posting your ARC schematic. I am learning from it.

And I'm learning from everybody's thoughts. Electricity is slithery stuff (I borrowed that notion from a celestial navigation teacher who pointed out that time is slithery stuff).

[High Hopes]

Rigsy,

I went to the link and now understand that type of the battery switch. Both batteries are disconnected.

I came up with an alternate approach last night using the existing battery switch. However, it doesn't disconnect the engine.

Originally Posted by rigspelt

And I'm learning from everybody's thoughts. Electricity is slithery stuff (I borrowed that notion from a celestial navigation teacher who pointed out that time is slithery stuff).

So do you navigate with a sextant, clock, and compass?

Steve

[rigspelt]

Originally Posted by SteveMarkowski

Rigsy,
So do you navigate with a sextant, clock, and compass?

I can (Astra IIIb, chronometer and Plastimo Iris 50), but I much prefer the GPS chartplotter combined with paper charts -- another thread, this.

[rigspelt]

A wrinkle: On shore power, the ACR will parallel the batteries once the primary battery is charged up to the ACR set point. If the shore power charger sends a separate lead to each battery to charge them independently, this parallels the charger outputs too. According to Blue Sea there are workarounds for this:
1. If the shore charger runs a single program to move the batteries from bulk to absorption, there may be no problem running separate outputs to each battery and letting the ACR parallel when it wants to.
2. If the shore charger is more complex, Blue Sea has an application note on their website for installing an AC powered relay that opens the ground connection of the ACR when the shore charger receives shore power. That disables the ACR while on shore power, letting the shore charger do its thing on each battery separately.
3. Run only one output wire from the shore charger to one battery (house) and let the ACR kick in to maintain the engine start battery after the house battery comes up to charge. On the dock, most likely the only draws will be from the house side.

I have not decided which direction to go yet, so I have not updated the wiring diagram draft.

[msauntry]

When I rewired, I found two common positive buses useful.

IGN to first bus powers the cockpit gauges

Wire from first bus to second bus in engine compartment powers all IGN related stuff there (hour meter, coil, fuel pump, etc.)

Otherwise your coil positive and IGN switch get stacked with leads...

[msauntry]

I also changed from the old turn key/push button start to a 4-way keyed ignition switch from Cole-Hersee (West Marine, etc.). It has an "Accesory" position that I found perfect for the Blower. I found it irritating to have to go down to the DC panel to flip on the Blower each time I started the engine. Now its done at the key in the cockpit.

[rigspelt]

Originally Posted by msauntry

When I rewired, I found two common positive buses useful. IGN to first bus powers the cockpit gauges. Wire from first bus to second bus in engine compartment powers all IGN related stuff there (hour meter, coil, fuel pump, etc.) Otherwise your coil positive and IGN switch get stacked with leads...

Good point: I need to show the new electric fuel pump. I will indeed add a bus up at the engine for the IGN stuff. I already have an IGN bus at the panel. I'm going with a 3-position key switch, and putting the blower on the house circuit with a switch in the panel.

[High Hopes]

Rigsy,

I vote 3.

It seems to me that if one chooses to use an ACR, then dual charging defeats the original intent. Charging is managed by the ACR. This design point offers simplicity - the original intent, no? Remember that your alternator is the biggest charger you have and it is not “smart” or sophisticated. If your design uses the alternator, why sweat the shore charger? Most of the finer points of smart chargers deliver marginal benefit for all the hype (IMHO).

If you want to get fancy, get a solar panel charger. Mine works so well, that I do not keep a charger aboard my boat. I never needed one. Both my batteries are mid-sized marine/SUV batteries. So far the ACR has worked fine. House lights are bright and the engine jumps when I crank it.

Steve

[rigspelt]

Originally Posted by SteveMarkowski

Rigsy ... why sweat the shore charger? ...

For the mate. Ice-maker.

[High Hopes]

Ah. That explains everything. -Steve