12 Volt problems / questions

[Bob Ohler]

On my CD 25 D today, I noticed the "pilot" light on the main fuse panel glowing slightly, even though the master switch was turned to the "off" position. After later deciding that the light was indeed on and not just reflecting sunlight, I unscrewed then panel to see if I could find any obvious loose connections. What was weird was that with the switch in "off' position, and the pilot light on, if I turned on one of the 6 accessory swtches on the panel, the pilot light would go out. To preserve the batteries for tonight, I disconected the ground wire so the pilot light would not burn all night. With the master switch in the off position, I thought I would try to see if power was getting to the ignition switch. I put the key in, and turned the key to the "on" position, and the warning lights and buzzer did indeed sound. With a voltage tester, and the master switch off, I tested and did verify that there was 12 volts on ALL 3 of the brass posts on the back of the master switch.
Did my master switch go bad... and is it possoble for voltage to flow through a bad master switch? (I think it's a Perko)
OR... Am I looking for a loose connection or worn insulation on two of the battery cables?
Thanks for your advise! Bob Ohler CD25D hull #2



Bobohler@chesapeake.net

[Duncan Maio]

Bob:

Are any of your electrical devices (bilge pump, loran, etc.) wired directly to the batteries, bypassing the master switch and the fuse panel? If so, a short or closed circuit could cause power to leak into the rest of the system. The "faint glow" on your pilot light suggests a power leak through a bad connection. Disconnecting any "hard-wired" connections one at a time should reveal the leak, if this is the problem.

Try disconnecting each of the batteries one at a time, and see if you still get what appears to be "output" from that side of the master switch. If so, there is probably power coming from somewhere else in the system.

Of course, if you have shore power, UNPLUG IT before you get back on the boat. A faulty ground could be the problem, and give you a very bad day.

Good luck!

p.s. I suppose the switch could go bad - mine is 20 years old, and is kind of touchy, but it tends to not connect at all if positioned incorrectly, rather than stay connected.



dmaio@worldnet.att.net

[Stephen C. Crampton]

On my CD 25 D today, I noticed the "pilot" light on the main fuse panel glowing slightly, even though the master switch was turned to the "off" position.

What happens when the switch is turned on? Does the pilot light glow brighter? (I assume it does if the battery is charged.)

I put the key in, and turned the key to the "on" position, and the warning lights and buzzer did indeed sound. With a voltage tester, and the master switch off, I tested and did verify that there was 12 volts on ALL 3 of the brass posts on the back of the master switch.

This tends to show that the switch works, at least as much as it does not pass current when off. If the switch was leaking current, I think you would show no voltage across the posts that were "leaky."

The proper way to test the switch is to disconnect it completely from the electrical system and test the various contacts for continuity with the switch in different positions.

OR... Am I looking for a loose connection or worn insulation on two of the battery cables?

I don't see how this would cause current to flow when the switch was off. A loose connection or worn insulation would result in intermittent (or permanent) power failure through disconnection or a short circuit.

I like the other poster's thoughts regarding a leak from a hard-wired accessory such as a bilge pump. Your comment that you disconnected the ground worries me.

It is critical to respect the difference between ground and hot leads. Improperly grounded systems can result in extremely fast corrosion of underwater metals (seacocks, props, shafts, etc.), discharged batteries, loss of lightning protection, and shock hazard.

According to an example in Calder's manual, a rudder fell off a sailboat because a compass light was wired backwards. What should have been the ground side of the compass light was wired to the hot side of the electrical system. With the light off, the current passed through the compass housing, the binnacle, and a steering cable, causing the rudder post to become positively charged. Current flowed through the surrounding salt water to the propeller, which was grounded to the engine and the rest of the boat's ground. The resulting corrosion to the rudder post was so bad that the rudder fell off!

In your situation I would look for an improperly wired bilge pump or other apparatus directly wired to your battery, undersized wiring on an appliance which is grounded (which could leak current through its ground), or some other source of a current leak.

That your lights and warning buzzer come on when you turn the key (althought the master switch is off) is a bit mysterious and raises concern. There must be some leak to your ignition panel somewhere. Do you have a special battery charger/isolation system on board? Is it possible that your battery charging system bypasses the circuit board? Also, do you have an shore power battery charger? That might inadvertently pass current to ground, especially if it is not a marine charger.

An excellent resource for any boatowner is Nigel Calder, Boatowner's Mechanical and Electrical Manual (2nd ed.). These issues are discussed in great depth in the first four chapters. Calder also has thorough troubleshooting procedures.

Good luck!

Stephen



sailing@star.net

[Dana Arenius]

Bob,

It sounds like a classic description of voltage leakage across the master switch. If your system is two battery Perko, then one would expect 12 VDC between two of the switch terminals to the common negative. These terminals come directly from the positive terminal of each battery. The voltage you see at the common terminal of the switch with the switch in the off position is leakage from one or both of the other two terminals.

The pilot light on your panel is probably a neon bulb. It requires very, very little current to illuminate it and has very high resistance. As soon as you turn on anything else in the boat, the voltage will drop and the neon light will go out. This is only an indication that the leakage path in the Perko has high resistance but does exist.

As I remember the Perko is a sealed unit. The best solution is to change it out. I am sure the problem will go away.

Until then, the only way to prevent the leakage is to turn off all the breakers and disconnect the light as well. As long as one breaker is on with a device activated, there will be leakage with the Perko in the off position.

Dana



darenius@aol.com

[PAUL]

On my CD 25 D today, I noticed the "pilot" light on the main fuse panel glowing slightly, even though the master switch was turned to the "off" position. After later deciding that the light was indeed on and not just reflecting sunlight, I unscrewed then panel to see if I could find any obvious loose connections. What was weird was that with the switch in "off' position, and the pilot light on, if I turned on one of the 6 accessory swtches on the panel, the pilot light would go out. To preserve the batteries for tonight, I disconected the ground wire so the pilot light would not burn all night. With the master switch in the off position, I thought I would try to see if power was getting to the ignition switch. I put the key in, and turned the key to the "on" position, and the warning lights and buzzer did indeed sound. With a voltage tester, and the master switch off, I tested and did verify that there was 12 volts on ALL 3 of the brass posts on the back of the master switch.
Did my master switch go bad... and is it possoble for voltage to flow through a bad master switch? (I think it's a Perko)
OR... Am I looking for a loose connection or worn insulation on two of the battery cables?
Thanks for your advise! Bob Ohler CD25D hull #2

BOB; YES, VOLTAGE WILL PASS THROUGH A FAILED MASTER SWITCH AND BASED ON YOUR DESCRIPTION IT POINTS TO A FAILED MASTER SWITCH.
I'VE FOUND SIMILAR PROBLEMS ON VESSELS IN THE PAST, IT WAS THE
SWITCH IN EACH CASE. AS FOR YOUR INSTRUMENT PANEL FUNCTIONING,
I ONLY FIND IT SURPRISING SINCE YOU STATE THE "PILOT LIGHT" IS
DIM. YOU DO NOT SAY WHETHER THE BUZZER IS NORMAL LOUDNESS OR IF WARNING LIGHTS ARE EQUALLY DIM AS PILOT LIGHT. THE LIGHT GOES OUT WHEN YOU SWITCH A BREAKER ON BECAUSE THE CURRENT IS DROPPING. IF YOU HAD REVERSED CONDUCTORS ON A PROTECTED CIRCUIT IT WOULD BE BLOWING THE FUSE OR TRIPPING THE BREAKER ON THE PARTICULAR CIRCUIT. OF COURSE IF A CIRCUIT ISN'T PROTECTED YOU CAN EXPECT TO FIND SIGNS OFELECTROLYSIS.

[Lee H. Hodsdon]

Bob,

Since you will need to replace your Perko switch you might want to consider an upgrade provided by West Marine. It is called their battery combiner, causes no voltage drop and assures adequately charged starting and house batteries. The installation was not too difficult, and yes it works! If you are interested I can provide detailes of what I did to my 25D. Just a thought.

Lee

On my CD 25 D today, I noticed the "pilot" light on the main fuse panel glowing slightly, even though the master switch was turned to the "off" position. After later deciding that the light was indeed on and not just reflecting sunlight, I unscrewed then panel to see if I could find any obvious loose connections. What was weird was that with the switch in "off' position, and the pilot light on, if I turned on one of the 6 accessory swtches on the panel, the pilot light would go out. To preserve the batteries for tonight, I disconected the ground wire so the pilot light would not burn all night. With the master switch in the off position, I thought I would try to see if power was getting to the ignition switch. I put the key in, and turned the key to the "on" position, and the warning lights and buzzer did indeed sound. With a voltage tester, and the master switch off, I tested and did verify that there was 12 volts on ALL 3 of the brass posts on the back of the master switch.
Did my master switch go bad... and is it possoble for voltage to flow through a bad master switch? (I think it's a Perko)
OR... Am I looking for a loose connection or worn insulation on two of the battery cables?
Thanks for your advise! Bob Ohler CD25D hull #2

lhodsdon@msn.com

[Bob Ohler]

A VERY strange problem was the root cause of my problem! The positive lead from battery #1, and the "hot lead" cable coming from the battery selector switch to the starter had apparently rubbed together over 15 years and power was crossing between the 2 cables. The REAL dilemma was that these cables were "captured" in the sealant and between the hull and the deck on the port side. It was not an easy problem. The bolts from one of the lifeline stancheons were touching the charged cables as well. (I had 12VDC in my lifeline stancheon.) The only remedy was to run new cables, and abandon the old (cutting off the excess lengths, of course). In order to get the cables from the back of the battery selector switch over to the side of the boat, it was necessary to drill a hole in the bottom of the hull liner immediately under the circuit breaker panel. The bond between the hull liner and bottom of the coach roof was simply too tight to allow the cables to be passed between the two, like on the original installation. Tjis was a problem 15 years in the making, and was waiting to happen from the day the deck was bonded to the hull. The new cables are going to be concealed inside some channel so that the inside cabin looks "finished'.
Bob Ohler CD25D hull #2



Bobohler@chesapeake.net