NEW INTRODUCTION 17 June 2012 - Unfortunately, the following article now requires a major correction (in addition to the one in the next paragraph), and, if anyone knows a good recipe for removing egg from a face, please send it along. My big assumption in this article, that the location of the terminals on the type of Guest battery selector switch aboard Hali (for which I could not find a diagram) were the same as those in a Perko battery selector switch (for which I did find a diagram), turns out to have been wrong. In the result, the conclusion I drew that the Guest terminal had been mis-wired was unjustified, and the follow-on conclusions I drew about that mis-wiring causing battery problems were foolish. I would like to delete the article, but it attracted comments that may be helpful to others -- and it may not be entirely useless to see how foolish another C34 owner can be. So the article survives to provide context -- and pain!
[Please mentally correct my following article in light of Maine Sail's later clarifying note that the common post/terminal (on the backside) of the battery selector switch is not the same thing as the Both position (on the front) of the battery selector switch, and that the Both position is not a terminal. The Guest battery selector switch described in this article has its common post/terminal immediately behind the Both selector position and, in this sense, differs from the diagram for a battery selector that Maine Sail provides.]
Like most boats, Hali is blessed by the presence of angels and cursed by the presence of gremlins. We have discovered that gremlins often operate in pairs or gangs, so that when you think you have solved a problem, it recurs and you find another gremlin laughing at you.
Since we acquired Hali -- our 1997 C34 Mark II -- in 2007, she has had a battery gremlin. The diet of this gremlin has consisted of a battery or two every year or two.
In case it might help others apparently afflicted with original mis-wiring at the battery selector switch, this is our story of (we hope) finally catching this gremlin.
Hali came to us equipped with:
1. an automotive starting battery ;
2. two 4D flooded lead acid batteries as house batteries;
3. an old battery charger;
4. a Marinco Guest Off-1-Both-2 battery selector switch (“Guest”); and
5. an electrical-relay-operated battery isolator/interconnect switch in the charging wire between the engine alternator (via the starter motor) and the Guest.
Over the years, sometimes prodded by discovering dead and dying batteries, we:
6. replaced the old battery charger with a Xantrex XC3012 battery charger;
7. added a Link 20 battery monitor;
8. added a “normally off” 15 pounds per square inch oil pressure switch in the alternator-to-Guest charging circuit, so that the alternator would charge the house batteries (in addition to the starting battery to which it is directly connected) once the engine had started and engine oil pressure had risen to at least 15 psi;
9. a switch, parallel to 8 and connected to 5, that is usually left off so as not to connect the house batteries to the engine for starting purposes but that can, by setting it to “On”, link the house batteries to the engine if the house batteries are needed to help start the engine.
In making these upgrades, we did not create our own wiring diagram or check the original wiring connections on the Guest. (Stu Jackson would undoubtedly say these omissions were bad mistakes. We would now agree.)
The battery gremlin brought matters to a head this year when, for the second year in a row, he ate Hali’s #1 house battery and began eating #2 house battery.
In previous years, we had guessed that similar problems had been caused by:
(a) a defective battery charger – hence the purchase of 6 and our first round of new 4D batteries;
(b) the electrical drain of a relay switch – hence our installation of 7, 8, and 9; and
(c) a bilge pump that operated more than we realized – hence our installation of a bilge pump cycle counter (which established the bilge pump was not running frequently).
In retrospect, it is apparent that in those previous years we had been only guessing at the identity of the gremlin and that we had thrown money at imagined fixes instead of getting to the bottom of the problem.
This year, it was time to get serious and trouble-shoot the whole electrical system.
We learned how to use a multimeter. We made a wiring diagram.
Still, our gremlin took days to come into view.
Along the way, we realized that we did not really understand how the Guest worked.
We never did find a manufacturer’s diagram for the Guest but, based on a diagram for a Perko battery selector switch that is assumed to operate similarly, it appears that the Guest should have been connected up as follows:
• Guest terminal “1” connects to house battery #1 positive terminal
• Guest terminal “Both” is the common terminal to which the “charging circuit” from the engine attaches;
• Guest terminal “2” connects to house battery #2 positive terminal
But how was our Guest wired up?
A wire properly connected Guest terminal “1” to the positive terminal of house battery #1. But the wire from the positive terminal of house battery #2 terminated at Guest terminal “Both” instead of at Guest terminal “2”; and the engine charging wire connected to Guest terminal “2” instead of to Guest terminal “Both”.
This mis-wiring, which seems to have been with the boat since she was built, had unfortunate consequences.
When Guest “1” was selected, no charging current from the engine ever reached house battery #1. (With the battery selector at that setting, we believe normally a connection would be made between the Guest terminal “1” and the Guest common (Both) terminal, with the result that if the switch was correctly wired, a charging voltage would reach house battery #1 by the route: engine alternator to Guest terminal Both to Guest terminal 1 to house battery #1 positive terminal. But as the charging wire connected to Guest terminal #2, no charging voltage reached house battery #1 when Guest “1” was selected.)
All was well insofar as charging the house batteries from the engine was concerned if the engine was running and Guest “Both” was selected, because then the Guest connected, as it should, all three terminals (1-Both-2) together, and both house batteries #1 and #2 received a charge.
But, if the engine was not running and no shore power was running the 110 volt shore powered battery charger and Guest “Both” was selected and the house battery #1 was run down – a set of circumstances that occurred when anchored-out while cruising -- house battery #2 would try to charge house battery #1, and the gremlin who had attacked house battery #1 would begin destroying house battery #2.
We have speculated why the system was mis-wired in this way.
Our conclusion, which may be completely unfair to someone, is that the factory electrician pulled a short charging wire or cut it short, so that it could reach Guest terminal “2”, which is lower down on the Guest, but not reach Guest common (Both”) terminal, which is higher up. Faced with the nuisance of pulling a new wire, the electrician (we speculate) chose the expedient work-around of connecting the wires to the "wrong" terminals. But the wiring was only "wrong" if you didn't know the workaround and selected something other than Guest "Both".
For years, we had noticed that the shortness of all the major wires to the Guest severely limited how far the electrical panel (where the Guest is located) could be opened. We were simply unaware of the electrician's work-around. In our early days, we usually did select "Both", but in recent years, we fed the gremlin by selecting Guest "1" and cut back on our use of shore powered battery charging.
Our solution this year, which wiring codes might not have allowed the Catalina electrician (assuming he was the culprit), has been to add a short pigtail onto the engine charging wire and re-wire the Guest correctly. Now, the selection made on the Guest means what we had previously, intuitively but incorrectly, thought it meant. If Guest “1” is selected and the engine is running, house battery #1 is being charged and house battery #2 is not being charged. If Guest “Both” is selected and the engine is running, both house battery #1 and house battery #2 are being charged. If Guest “2” is selected and the engine is running, house battery #2 is being charged and house battery #1 is not being charged.
Our conclusion that original mis-wiring is the gremlin responsible for Hali's dying batteries has not yet been proven by the passage of time.
We still fear the appearance of a battery-eating larger-brother gremlin.