Electrical Problem

[DeepFrz]

He cleared up my confusion on the key switch. It is a separate switch, not the engine switch, that he uses to turn on the charger. The engine key has to be removed in order for him to activate the charger.

I agree that without a wiring diagram we are all just guessing. Maybe some wiring got messed up when you were replacing the pump?

[Captain Koch]

Originally Posted by DeepFrz

He cleared up my confusion on the key switch. It is a separate switch, not the engine switch, that he uses to turn on the charger. The engine key has to be removed in order for him to activate the charger.

I agree that without a wiring diagram we are all just guessing. Maybe some wiring got messed up when you were replacing the pump?

Yep. Could be. I hooked up a old bilge pump with reversed polarity and it ran back wards. That is also what three phase motors do.

[stevesailing]

thanks all for your thoughts - I'll go down to the boat tonight and investigate further. I think it is unlikely to be a result of the replaced pump/switch as I replaced them with the same model and connections.

Hellosailor - the alarm is not a battery alarm, it is the buzzer which sounds with the engine circuit is turned on but there is no alternator charge / oil pressure etc

skipmac - the engine ignition is switched all the way in the off position. I'll check tonight and see which of the warning lamps illuminates, at least one of them does but as I was looking from behind the gauges I couldn't be sure which.

Captain Koch - the solar panel is on a switch which can be on when either of the other charging systems is on. I have heard different opinions on whether it should be turned on when either of the others is running. I admit to forgetting to turn it off when the alternator is running from time to time but that doesn't seem to have any adverse effect. It was a pretty dull day so I doubt the SP was generating much current.

[stevesailing]

Ok, I got down to the boat last night and found:

- contrary to the wiring diagram, the solar panel is not connected to the input post on the isolator, it is connected directly to the house battery output post on the isolator

- the alternator seems to work, ie produces charge to the batteries

- only the battery light / alarm is activated when the charger is turned on, ie the oil pressure / temp and other alarms

- the buzzer doesn't sound when the alternator is disconnected from the battery isolator and the charger turned on

So, current must be travelling from the charger to the engine circuit, via the alternator.

Is there something I would expect to find that would prevent that, eg is it usual for alternators to have a diode preventing current passing the wrong way?

thanks in advance.

Steve

[Captain Koch]

Originally Posted by stevesailing

Ok, I got down to the boat last night and found:

- contrary to the wiring diagram, the solar panel is not connected to the input post on the isolator, it is connected directly to the house battery output post on the isolator

- the alternator seems to work, ie produces charge to the batteries

- only the battery light / alarm is activated when the charger is turned on, ie the oil pressure / temp and other alarms

- the buzzer doesn't sound when the alternator is disconnected from the battery isolator and the charger turned on

So, current must be travelling from the charger to the engine circuit, via the alternator.

Is there something I would expect to find that would prevent that, eg is it usual for alternators to have a diode preventing current passing the wrong way?

thanks in advance.

Steve

The voltage would be going from the battery terminals to the turned off key ignition. Also from the battery to the chargers and solar. They have to be off or in some cases disconnected completely in order to not send or receive voltage. Only connect or turn on one charging source at a time of course.

[hellosailor]

"eg is it usual for alternators to have a diode preventing current passing the wrong way?"
Not a diode, but the diodes (6 or more) in the diode frame do prevent current from going backwards through the alternator. If one or more of those diodes is bad, the alternator will drain the battery when it is not running, and it will feed some AC to them when it is working. I don't think that would trigger a battery alarm but it is something to check & eliminate easily enough.

[Captain Koch]

Originally Posted by hellosailor

"eg is it usual for alternators to have a diode preventing current passing the wrong way?"
Not a diode, but the diodes (6 or more) in the diode frame do prevent current from going backwards through the alternator. If one or more of those diodes is bad, the alternator will drain the battery when it is not running, and it will feed some AC to them when it is working. I don't think that would trigger a battery alarm but it is something to check & eliminate easily enough.

With a volt meter you should be able to find the problem easy.

[skipmac]

Originally Posted by hellosailor

"eg is it usual for alternators to have a diode preventing current passing the wrong way?"
Not a diode, but the diodes (6 or more) in the diode frame do prevent current from going backwards through the alternator. If one or more of those diodes is bad, the alternator will drain the battery when it is not running, and it will feed some AC to them when it is working. I don't think that would trigger a battery alarm but it is something to check & eliminate easily enough.

This would be my guess. If one of the internal diodes failed short then it could allow voltage from the charger to feed backwards into the ignition switch and activate the alarms on the engine.

[DeepFrz]

I would suspect the internal voltage regulator assembly inside the alternator. That is a big guess because you haven't said if it is internally or externally regulated, but I would guess its internal. You also haven't mentioned what make of alternator you have.

Does it look like this, ie: are the connections the same or similar to this one? (I hope this link works)

http://www.google.ca/url?sa=t&rct=j&...66699033,d.b2U

[smac999]

I would say you have a bad alt too. it probably has an ignition wire on the back of it. and the alt is back feeding the ign wire from the main battery cable. which is essitlally the same as turning the key on.

hook everything back up. and unplug the small wire(s) from the back of the alt. normally a plug. and see if that also stops the alarm.

I've seen bad alts drain power from a battery before, but I have never seen the back feed the ign circuit before. learn new stuff everyday.

[stevesailing]

Further investigation reveals that the alt is a Balmar OE60-100. The documentation says that it can be used with an ext reg or can use its internal reg. On my boat is it using the int reg.

There are a handful of small wires on the back. One of which (brown) has a diode and leads to the ignition switch. With everything else connected as normal but the ignition wire disconnected the alarm doesn't sound when charger is turned on, so my suspicion is that the diode is fried. This is given further weight by the packet of replacement diodes with one missing, suggesting this has happened previously.

I'll replace it and see it that fixes the problem.

thanks for taking the time to make suggestions.

regards,

Steve

[mrm]

Originally Posted by stevesailing

There are a handful of small wires on the back. One of which (brown) has a diode and leads to the ignition switch. [..] This is given further weight by the packet of replacement diodes with one missing, suggesting this has happened previously.

Steve, if you have time for that, I would suggest to carefully examine the wiring on your boat and draw a diagram of what is connected where. What you described so far makes me suspicious about qualifications of a person who did/modified the wiring.

Originally Posted by Captain Koch

[on chargers] They have to be off or in some cases disconnected completely in order to not send or receive voltage. Only connect or turn on one charging source at a time of course.

CK, WDR, your statement is contrary to accepted practice and in at least one case will result in immediate damage to charging equipment. Could you provide your qualifications to give advice on this subject and expand on technical reasons for such?

[hellosailor]

steve-
Easy enough to check the diode. Set the multimeter to ohms, any scale i.e. 200 or 2000 or 2M ohms. Test the diode, now reverse the leads and test again.
A good diode should give you a reading of infinite one way, zero the other way. Or very close to that.

A blown diode probably will say zero both ways, or infinite both ways.

[stevesailing]

Hi,

I'm hopeful that testing/replacing the diode on the weekend will fix the problem. I thought some of you might be interested in this further information from Balmar.

"The reason the diode is there in the first place is to provide the approximate battery voltage on the output of the alternator. If it weren’t there or it failed open, then the regulator couldn’t turn on the alternator’s output. The reasons are probably more than just one. However, it’s perhaps most important, because if the regulator can’t see the alternators output voltage it increase the voltage to high, which might lead to the damage of the alternator and other DC Appliances."

[hellosailor]

Steve, that quote may be one of the most painful manglings of the YnGlitch language that I have ever heard.

I'm sure they mean something, but whoever said it probably should have used the Google Translator or Babblefish instead of trying to make Ynglitch.

Sounds like "that diode prevents overvoltage in the event of certain failures" and if the diode itself can burn out, as yours has, that's a poor kludge as well.

BTW if the diode is not firmly supported, attached to something solid with the leads secured as well, the normal vibration of an engine and alternator can literally break the leads off a diode that's just "hanging" there. Semiconductor leads don't like being wiggled for long periods.

A small piece of circuit board, proper mounting, a heat sink...these things would quadruple the cost but probably ensure the diode didn't fail again. Assuming it was spec'd right in the first place.