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Old 16-06-2003, 18:45   #1
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BASIC Alternator Testing

I'd be very intersted in hearing any comment and/or criticism of the following rough draft.

Draft Copy - June 16/03
INTRODUCTION to TROUBLESHOOTING
by
Gord May - Copyright by Gordon A. May 2003 - All Rights Reserved

GENERAL INSPECTION:

A loose drive belt can cause slipping and undercharging, noise and vibration, and premature belt wear. An over-tight belt may cause bearing wear.

Look at and feel the drive-belt, examining for cracking, fraying, glazing, and/or separation. Replace damaged belt(s).

Test the belt tension by firmly depressing midway between the sheaves. The belt should deflect between 1/4" (for sheaves with 7" - 10" centerline separations) and ˝" for 12" - 16"separations). Adjust tension as necessary.

Inspect all wiring and terminations. Wire should be adequately sized for the application (see “Ohm’s Law & Boats”), secured at least every 18", and run as high and dry as possible. Termination s must be clean (no visible corrosion), and tight. Examine the wire for thermal (melting or charred insulation) or mechanical damage (frayed, cracked, or missing insulation).
Replace damaged or undersized wire, and replace or repair inadequate terminations.

ALTERNATOR VOLTAGE TESTS:

1. Set Voltmeter to DC Volts (20V scale), and connect the DC Voltmeter test leads to the battery post (Red lead to Positive Post, and Black(or Yellow) to Negative). With engine “off”, read and note battery voltage (see “Battery Testing”).

2. Start the engine, and at “Idle” RPM, check the voltmeter reading. At very low speeds the alternator output may be lower than the regulator setting; hence you will expect to read the battery voltage.

3. Increase engine RPM, and note increasing voltage reading to a maximum of about 14.2 volts (12V Nominal System - expect ± 29.5V in 24V system).

If no voltage increase noted, you likely have a bad voltage regulator, or poor wiring
(Alt’ to Batt.). Go on to test 3B.

If Voltage increases go on to test 4.

3B. With engine “off”, connect Positive test lead to Alternator Output (“B+”, or “A”), and Negative Lead to the Negative Ground Post (“Neg”, or “E”) of Alternator. Start engine. If Voltage increases with increased RPM, your regulator is OK, and the problem is in the wiring. Go on to test 3C.

3C. Discharge the Battery to less than 12.5 Volts. Check for Voltage drop between the Alternator and Battery, as follows..
Connect the Positive Test Lead to the Alternator Positive Output Terminal (B+) and the Negative Lead to the Positive Battery Post. Crank the engine, and increase RPM to a fast idle. Observe Voltage. If the voltage climbs to as much as 0.02 Volts (or more), the positive cable has a high resistance. Repair or replace cable.

Check for voltage drop in the negative cable, as above - but: connect the Positive Lead to the Alternator’s Negative Output Terminal, and the Negative Lead to the Negative Battery Post. Analyze as above.

E. & O. E.
Gord May
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Old 24-08-2003, 05:15   #2
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Good reading on Alternator trouble shooting...

Have a related question:

The voltage regulator would cut out and will not let the alternator charge at all after motoring for 10 to 15 minutes. The remedy seems be to stop the engine, shut the "ignition" off, then restart the diesel. and everything be working fine again.

The alternator is a 150 amp "PowerLine" and the regulator is a 3 step smart unit also from "PowerLine". After cutting out it would flash 2 green lights witch is a code for short circuit....

While working at full blast the regulator/alternator puts out 14.4 volts, tapering off to 13. 2 as the logic in the regulator is doing its thing.

Swapped the alternator out with the spare one and the same happened, therefore the problem is not with the alternator, but rather in the regulator....But how could there be a short in a solid state regulator...And if there was, why would the short go away as soon as ya shut the power off, then restarted and everything be fine....Sometimes for several days, then it happens again...One of those small problems that drive ya crazy because it is hard to pin-point.


Should also mention that I have 2 solar panels hooked up to the housebank via the battery isolator, and thru an NC-25 charger.

Wonder if it perhaps is the solar panels that wreck havoc with the system, but then the alternator's regulator should show an over-voltage condition/problem, not the code for a "short circuit".

Been thinking about an on-off switch for the solar panels anyway, but hesitate as there is probably a loss over such a switch?
Right now I have "un-broken" 10 gauge duplex tin plated copper wire from the panels straigt to the solar regulator.
(Get about 50 amps a day from the panels, they run my fridge and freezer and the anchor light.....Good deal for sure)

So what is your opinion on the above?
Faulty wiring somewhere?
Bad regulator?
Solar panels creating problems with the charging system?
Gremlins?

Any input be much appreciated...Buy ya a beer..
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Old 24-08-2003, 06:58   #3
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Remote Regulator Troubleshooting

Interesting problem. I’m terribly inept @ long-distance troubleshooting (& not all that bright), so this could take a while, and a bunch of back & forth Q & A. I’m not specifically familiar /w “Powerline” gear, so bear /w me...

To start with simpler things first:

1a. Is this a new problem, with a previously working installation (both alt’ & reg)?
1b. Or are you uncertain that it ever worked properly?

2a. Is the regulator mounted where it could overheat (>1800 F)?
2b. Or where it suffers significant vibration (moisture or other harassment)?

3a. Does it continue to work fine, for extended periods, when you shut down engine, then re-start?
3b. Or does it re-cycle in a repeating failure pattern?

4. Does the regulator have a “Duty Cycle” potentiometer (field adjustable)?

5a. Check for an intermittent, or otherwise poor GROUND connection. OK?
5b. Check the rest of the wiring harness for intermittent faults or corroded connections.

6a. You say that two flashing green lites indicate “short circuit” - is there a small amp fuse in the voltage sense wire and/or a bigger one in the Regulator power supply?
6b. The fuse does not “blow” when short circuit indicated?
6c. Check the fuseholder for intermittant problems.

Gotta get back to (paying) work.

More later, pending your answers. Patience pays ...

Regards,
Gord
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Old 24-08-2003, 08:15   #4
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Thanks for quick come-back..
Paying work on a Sunday..? Hmm, yr supposed to be out sailing.:-)

To start with the answers:

1 a and b)

Yes, this is a new problem. The boat is 24 years old but was re-wired with new electrics about 8 to 9 years ago.
I owned her for 5 years. Never had a problem with the charging system, or anything electric. All good quality gear and proffesional
work.

The problem started about a month ago and has happened 3 times so far. I contacted the factory, they gave me the answer for the 2 flashing green lights and said the problem could be in the alternator or regualtor....That is why I swapped the alternator for the spare, to eliminate or confirm one possibility.

2 a and b)

As for overheating the regulator, no don't thinks so. It is in the engine compartment, aft of the valve cover and opposite from the exhaust, yes it get a bit warm in there, but not super hot.
No abnormal vibration or any moisture......Well, there was the raw-water loop with an malfunctioning anti-siphoning valve that would squirt a few drops of salt water around every 10 seconds and it did some damage..I repaired most of it, but there could have been some salt spray finding its way over the junction box and the regulator.
BUT, that was taken care of a year ago, and the problems started last month.
Perhaps corrosion works over time, even when the source is removed?

3 a and b)

Yes, the system works fine for extended periods of time, and no it does not cycle.

4)

No, there seem to be no user adjustment on the regulator, but I could look again and read the booklet once more.

5) OK, will check for bad ground and also look over the rest of the harness.

6)

If there is a fuse in the voltage sense wire, I am not aware of it, but I should know.
(Since the system has been working fine for years, I have not paid much attention to the nuts and bolts of it, but now I should dig into it for sure.)

I noticed that a similar problem would occur occasionally after I installed the first solar panel 3 years ago.
With a strong sun and motoring down the coast, the RPM needle would all of s sudden drop ot zero, indicating that the alternator or regualtor cut out.
It would come back to life after 10 to 20 minutes with no action on my part, OR I could get it back right away by increasing the load on the panel, lights and radios, etc.
Did not however check the regulator for error-code light signals at the time, but it seemed fairly "Normal" that the main regulator would say:
"Hey, the batteries are top-charged, and something else is charging 'em also, I am not needed for now, so I am taking some time off and when the voltage drops off again, I am going to wake up and do my job once more"


Uh, does that make sense to you...?

At any rate, okay, I will go onboard today and poke around a bit more. Perhaps undo some wires and clean 'em up.

Thanks again for the input.

Free beer next ime ya are in Florida....
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Old 24-08-2003, 09:16   #5
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Yes, the solar panel output could "fool" the regulator , and instruct it to shut down - but then I wouldn't expect the 'short cct' error code.

Because the fault seems to be VERY intermittant, and failing any other obvious etiology, I'd really take a good look for loose or corroded wiring connections.

Let me know anything else you discover, and I'll give it some more thought, and report anything else that occurs to me.

I did say "paying' work, but I should have said un-paid overtime. When self-employed, I tried to limit myself to 20-25 Hrs a week. Now salaried, I work 20 hrs a weekend. Told you I wasn't too bright!

Free beer? How 'bout Durty Harry's, for a jug and a bunch of wings? How I miss Fridays at Harry's!!!

Regards,
Gord
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Old 24-08-2003, 09:33   #6
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Aye, so ya know about Durty Harry's?

Yup, that is the local hang-out for the CSY guys in Ft. Lauderdale.

We have had frequent meetings there and them wings and the cold beer goes down pretty smooth.

The wifes is not too impressed with the place, they call it another sleezy bar...Which of course is the secret to the whole thing:
Honey ya wanne go to a CSY meeting tonight?
No, that is okay, I will stay home and watch the tube......
So the boys get out and away, lies are told and beer is flowing and no hard feelings from the ladies, becuse they WERE in fact invited as well.....

So, yup see ya over at Durty Harry's for a round of brew.

As for the wires and such, will take a look today, running out of excuses for not stepping on the boat and doing something useful..
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Old 30-08-2003, 10:34   #7
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Alternator regulators and solar panels

Hi guys:

I do like your alternator tests, Gord. Gonna try them out. I have been using Nigel Calder's book, but your write-up is a good to-the-point guide.

The business with alternators and solar panels intrigues me. I had a feeling that anything done on the alternator side of the diodes could cause trouble with the built-in regulators of most alternators. This sounds like the above problem. I have a 35 foot cat with two 55 amp alternators charging a 3 bank system through a single diode block. The block has two bolts for incoming, and 3 bolts for outgoing power. I figure I'll set up two "Canadian Tire Battery Saver Pro 15 W solar panels, but hook them up to the house bank on the battery side of the diode block. I suppose I'll have to get the matching regulator. I would like also to go with wind, but may sneak up to it with the solar first.

Comments?
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Old 31-08-2003, 04:03   #8
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Solar Regulators

Sonosailor:

Charge Controllers (voltage regulators) are not generally required on Solar Cells that produce less than 1.5 to 2% of the Battery capacity. In this case, a Blocking Diode (Shottky) is recommended, to prevent battery feedback at night (& under overcast).

I don’t recommend cheap Charge Controllers (this gets pretty technical). They can do more harm than good (to the batteries they are supposed to protect). If you do install a controller, you won’t require blocking diodes.

Because the good controllers (pulse width modulation, &/or max. power-point tracking) are expensive, I’d first try running the Solar Panels unregulated (/w blocking doides), and monitor the actual output and battery condition. In your latitude, you may not be at risk of overcharging (boiling) the batteries.

I'd expect your 15W panel to put out less than 1 Amp over less than 5 hours/day (< 5A/H) so you'd be marginal feeding a pair of T105's (for instance). You are close enough to the trip point that you need actual input data.

Finally, I'd probably wire a 2-Pole Solar Panel disconmnect switch - to disconnect panels when alternator running. (This could also solve CSY Man's problem - tho' I'm still confused by his "Short Cct." indication).

Regards,
Gord
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Old 31-08-2003, 07:01   #9
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Mr. GordMay:

Yes, I considered such a cut-off switch for the solar panels, and it is still on the list of things to do, but pretty far down the list....

Have not had time to lay down on my knees and take the junktion box apart and scrape corrosion yet. (As far as trouble-shooting my regulator problem)

Been side tracked with other projects, like getting a couple of coats on Bristol Finish on the teak between the showers...

You said somewhere else on this forum that you were considering getting a project boat around 30 feet or so..?
Well, there is a Pearson 30 here in Ft. Lauderdale that is free for the first guy that will come and get it..
Interested.?
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Old 01-09-2003, 03:03   #10
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Pearson 30

CSY Man:
Well the price seems ok
Please tell me more. I'm interested, but FLL to Thunder Bay would be pretty expensive.
Thanks & regards,
Gord
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