Alternator/Batteries & "The Basic" 1-2-B Switch BEST Wiring Diagrams

[Stu Jackson]

Yes.  An echo charger would be better than a combiner for a reserve bank because it is current limiting to the reserve bank and doesn't ever "combine" the banks..  We put a switch in our combiner (-) leg for a shut off in case we motor for long periods. The "hot wire" from the alternator to the house bank should be sized to carry the current you have or plan to have, and appropriately enlarged if considering a high(er) output alternator in the future to avoid having to rewire later.

[DaveM]

Stu
Thanks for the point on the echo charger.  I honestly had not noticed that detail, but is obviously important.  When you say you put a switch on the negative (-) leg of the echo charger do you mean the ground lead or the output leg to the starting battery.  Would it be better for the switch to be on the house battery side to isolate the echo charger?  Thanks
Good Winds
Dave M

[Stu Jackson]

Dave, Notice I said "on our combiner" not an echo charger.  The concept is the same, although the echo charger is current limiting.  If you want to be able to turn off the automatic battery connection that the relay provides, you will need to read the instructions in your echo charger manual.  My combiner manual allows for doing this on the negative lead from the combiner relay to the NDP (battery ground post near the battery box before the negative goes to the engine).  I do this to avoid combining the banks when motoring for long periods to avoid overcharging the reserve bank.  It's not the "side" it's on, Dave, it's to disable the relay from closing.

Added 6/29/2015:  Maine Sail has corrected me by reminding me that batteries can't get overcharged UNLESS the voltage is too high.  Check out "Electrical Systems 101" or do a search on MYTH.

Added 10/21/11:  Echo chargers do NOT need to be turned off.  I was wrong.

[Stu Jackson]

Here's another good wiring diagram, courtesy of clj1950 from sailnet

[Ken Juul]

I've been suffering some charging problems. Which lead to reexamining how I set up my system.  If you move your alt charge wire so it goes directly to the house bank, you also need to move the Alt Sense wire and the 12v feed to the engine instruments off the starter post and on to either the house load side of the 12Both switch or the house bank itself to get proper voltage indications and alternator regulation.

[Ralph Masters]

Ken,
If you simply remove the wire going from the alternator to the starter and leave the other wires still attached to the positive post, alt sense and instrument feed, you should not have any issues with those two.  You will still have positive power from the battery going back to that starter post for the alt to sense and to feed the instruments.  You're just moving the output to a different position.  Am I right??  This is my next project on Ciao Bella for after the holiday.

Ralph

[Ron Hill]

Ken : By no means am I an electrical whiz, but I believe that you are referring to the voltage regulator "battery sense" wire. 
I believe that Ralph is correct, just reroute the alternator output wire direct to the battery banks and the other wiring should be fine.

I've had a couple of differant voltage regulators over the years.  One had a sense wire going to the battery bank, but the latest had a sense wire going to the key switch ON/OFF pole.  I believe that latest also powered the V regulator and also shut off all power to the regulator& alternator when the key was off vrs when the batteries were off.   

A few thought from a plumber!!   

[Ralph Masters]

Thanks Ron.

Happy Thanksgiving..................

Ralph

[Ken Juul]

Here is a diagram of how the boat is currently wired.  As is, if everything works there is no problem and it worked well for the last season or so. Recently my ACR died.  Therefore the start battery was not getting a charge from the alternator.  Because the sense wire stayed at a constant 12.x volts, not the 14.x volts the alt regulator was looking for the regulator just kept upping it's output voltage....I was seeing 16-17 volts at the house battery.

Granted my set up is unique, the house bank is not connected to the starter except in an emergency.  Bottom line, the sense wire must be connected to the battery that the alternator is charging. 

As far the power for the engine instruments.  It can come from either battery.  I knew I was only reading the start battery voltage in the cockpit and was ok with that.  Until the unexpected ACR failure.  I was lucky I caught the high charging voltage before battery damage or worse.  I now think the prudent thing to do is to move the engine instrument power to the bank the alt is charging so it can be monitored in the cockpit when motoring.

[mainesail]

Ken,

The safest way to wire a "sensing" wire is to run it to the SAME battery that the alternator output is run to. Why? You now know why.. 

In the event of a failure of a device like an ACR or Echo Charger the house battery will be getting current but the voltage will not be rising thus the regulator thinks nothing is happening and continues to apply max field to the alternator which will eventually blow the voltage through the roof on the house bank because the voltage feedback from the start battery is staying flat and not responding the way the regulator needs it too.

[Stu Jackson]

Ken,

Me, too!   

See Reply #17 here:  http://forums.catalina.sailboatowners.com/showthread.php?p=846963

Uhm, "tomorrow" never came from that post.  It does, however, remain valid for me, and I am assembling the parts to do the correction.

We have an external Balmar MC-612 regulator for our Blue Circle 100A alternator.

My goal, as stated in that link, is to remove the battery sense wire from the alternator and wire it from the regulator to the house bank.  Please note, however, that the instructions say you can leave it on the AO.  By doing that, I kinda "induced" that 1.2V drop, because the battery sense wire wasn't on the house bank but only on the back of the alternator.

Shoot, I must admit I DID read the instructions!!!     So much for doing THAT anymore...

After repacking my stuffing box and putting in a new bilge pump switch today (F*ck Rule for changing both the height and spacing of the screws to hold the damn thing down!!!), I looked at my records, sketches and wiring diagrams, and know that I have a couple of well labeled and identified abandoned wires that I may be able to use to connect the regulator battery sense post to the house bank and get it off the alternator output (AO).  A month or so ago my son and I attempted to run that new wire I mentioned in that linked post, but the pull cord I cleverly installed a few years ago, underneath the engine from the stuffing box to the area under the galley sink by the hot water heater, was hung up on something and didn't allow us to do it then.

That's why they invented "tomorrow."

So, Ken, then consensus is:  sense the house bank.  Regardless of whether you have external or internal regulation for your alternator.

Thanks so much for pointing this out.

*********************************************

For those of you who "don't do links" (imagine that!), here's what I said:

This is a perfect example of real world issues. Like, take me, for instance!!!

I took the "shortcut" route of having the battery sense wire connected to the AO when I installed our MC-612. As you know, we also have a Link 2000. By habit, I would check the voltage at the regulator, and the amperage at the Link. Always looked fine to me.

Last week, after two grueling days of motoring, I happened to check the voltage at the Link 2000, and GUESS WHAT?!?. I was losing almost that same 1.2 V that Maine Sail described.

Just yesterday (really, honestly ) I bought a length of wire to finally install the battery sense wire to the bloody batteries, just like the instruction manual tells you to do.

I spent a week checking connections and confirming the integrity of my AO wiring, grounds, the shunt - you name it.

I finally came to this same conclusion, and all because: first I'd been lazy in the installation, and second, because while I have great instrumentation, I'd only been using the AO voltage display at the regulator and the amperage at the Link, not reading the voltage at the Link 2000 while the alternator was working - until last week when I thought "Houston, we have a problem!"

The battery sense wire goes in tomorrow.

Too bad there's not a "humble pie" emoticon!!!  YIKES!!!

[KWKloeber]

A long 'while' ago when I downloaded the pix, I had threatened to make a corrected version of the battery switch sketches posted in reply #20 below.  I just ran across them (forgot about doing it - CRS). If anyone wants a copy PM me and I'll email them.

[Stu Jackson]

A 'while' ago I had threatened to fix the battery switch sketches below.  I just ran across them, so here they are a little late.
(referencing reply #20 below.)

The link where I originally posted the diagrams is:  http://c34.org/bbs/index.php/topic,4949.msg30101.html#msg30101

That was in 2009.

I suppose the text from that post that reads as follows may not have been clear enough:  In the diagrams below, please change B to C.  B is a position on the switch, it is NOT a point of wiring connection.  There are three "posts" on the back of the switch: 1, 2 AND C.  There are four positions on the switch: OFF, 1, 2 and BOTH. Thanks.

[Stu Jackson]

........................and not rely on a (CRS) memory of an obscure correction that I may or may not have read sometime or remembered in the past........................

Yeah, right, obscure.  Sure.  In RED, too.

Thanks for the update.

I can't wait for what's next. 

[Noah]

Let's all play nice...