Conference unifix::sailing

                      <<< Note 1520.0 by CHOWDA::HEARNS >>>
                         -< Altanator help please... >-

You can test your alternator by putting a voltmeter across the battery.
Run the engine at 1500 RPM or higher, and turn on a lot of loads.
If the voltage is around 14-15V, the alternator is charging. If the voltage
is 12-13V or less, the charging system is not working. If you don't have 
a voltmeter, you can do a crude approximation of this test by watching a
lamp to see if it gets dimmer when you shut off the engine. If it gets dimmer,
the charger is working, at least to some extent.

--RS

    You can also put a VOM on the positive side of the battery and ground the 
    other. Variations in voltage with variations in RPM should indicate the
    alternator is working also.  If you can get to your alternator, you
    should be able to do the same thing coming off the + connector(s) on
    the unit.  We needed to do this this weekend unfortunately.  Not a good 
    weekend mechanically or electrically.  Glad we had our sails.  
    
    Brian
    

    Having just purchased a new outboard (Merc. 5 h.p.) with an optional
    alternator, I wanted to be sure it was actually charging my battery,
    which is on its 6th season. Middle of last week, I noticed that Radio
    Shack had a 3-1/2 digit digital multimeter on sale for $15.95 (which
    I purchased). Not only did it instantly show a rising battery voltage 
    when I started the motor, (and conversely, a slow drop with the motor 
    off), but I intend to keep it on the boat as a "state of charge" meter. 
    It's accuracy is 2% but I expect that it's repeatability will be much 
    better than 2%, and therefore quite useful for knowing how my battery 
    is doing.
    
    Bill
    
    

    After rereading the question in .0, here's a few more pointers.  I can
    sympathize a little here.  We had nothing but mechanical and electrical 
    troubles this weekend including dead batteries, bad solenoid, bad
    wiring, bad switches etc. etc. etc.  Very satisfying getting everything
    to work though. Still had a terrific weekend despite the troubles.  
    
    Your connections may be okay but look for broken or shorted wires.  A
    resistance check will tell you right away if there is an open in a
    wire.
    
    Your alternator may be fine but depending upon the rest of the system,
    the age of everything it could be several things that will give you bad 
    readings.  
    
    I believe there is a way to test if the Ammeter is shot though not
    exactly sure how.  I think you have to put a voltage through the gauge and
    see if it reads anything.  
    
    If your alternator is old or the system has not been maintained, you
    may have a bad voltage regulator, bad diodes, bad brushes etc all of
    which are replacable at a much lower cost than a new unit.
    
    Belt tension on the unit may be too loose. Should only be able to
    depress it in the middle by about 1/2 inch.  
    
    Good luck,  
    
    Brian

    
    
    To check out charging system:
    1. put voltmeter across alternator output terminal and ground
    2. take jumper and put +12v across field terminal of alternator
       (just for a couple of seconds) and observe meter
    
    if voltage rises- alternator is good, 
    
    if not alternator is bad- 
    take to any good starter/alternanor repar shop and they will fix it at
    much less than a new one
    
    If alternator is good,check voltage atfield terminal on regualtor-if no
    voltage, regulator or 12v feed to regulator not good. if voltage on
    output filed terminal of regulator, then the same voltage should be
    present at the fiiled terminal on the alternator
    
    I you have voltage to the input side of the regulator and none on the
    output, the regulator is bad- replace it.
    
    If you have no voltage to the input of the regulator look for a bad
    connection /broken wire from the ignition switch
    
    If you have voltage on the field terminal of the regulator, but none on
    the field terminal of the alternator- look for a bad connection/broken
    wire between the alternator and regulator. 
    
    Measure all voltages from ground (engine block)
    
    
    
    here's a simple schematic
                                            |------|
    ign sw.          __________             |      |
   +__--___________I|          |F__________F|      |B--------+        _-gnd
   \ to + on batt   |__________|            |------|         ------------
                     regulator  \              |             |   battery |
                                gnd          gnd             |           |
                                                             |           |
                                                             _____________
    
                   I= ignition or + input terminal on reg.
    
    		   F= field terminal on regulator  and/or alternator
    	
    		   B= Battery or output terminal on alternator
    
    
    battery and regulator should be grounded- there may be a ground
    terminal that should be checked on each of these.
    
    If alternator not grounded, will aplly full 12v to alt continuously 
    and burn it out
    
     I alternator is not grounded ther ewill be no output
    
    	

re .5:

Some alternators, eg, our Lucas (Lord of Darkness), have internal 
regulators that are not accessible without disassembly. And when 
disassembled it may not be at all clear which lead is the field (our 
Lucas again). 

re .0:

Alternators are usually easy to remove from the engine. If you don't
know much about electrical systems, why not just take it to an
alternator repair place and have it looked at? If it is not broken, the
repair folks can tell you what to look for. If it is broken, they can
probably repair it and maybe even tell you why it failed -- and the why
might well cause repeated failures unless corrected. 

    Seems the best place for this so here goes.  Partner was mucking about
    the engine compartment last week on vacation and by chance leaned on
    the alternator.  He noticed it was warm, much warmer than the engine
    which had been off for several hours and was actually cool.  Can anyone
    help with a reason why the alternator would stay warm?  The battery
    switches were on as well.  Isounds as if there was current flowing back
    into the alternator which sounds like bad diodes if there are any on it
    at all.  We have a Perkins 4.236 with a Lucas alternator/electrical 
    system.  
    
    Thanks,
    
    Brian

    Maybe some of the diodes in the alternator are shorted allowing current
    to flow back through.  This condition would discharge the batteries,
    possibly overnight if it were left in the circuit.  Although the diodes
    can be replaced, you will probably need a new or rebuilt alternator if
    this happens.  On most alternators, four diodes are press fit into
    round holes in the rear of the case.  You can take the alternator apart
    and check them with an Ohm meter.

    This seems to be the place for alternator questions...

    The Crocker has an alternator, but the surveyor tells us it is a car
    alternator.  Not too good with a gas engine, although the previous
    owner survived 12 years with it.

    Looking at the alternatives for a new alternator, we have been
    presented with two choices:
    	1. An automobile alternator that is built for marine use by adding
    	   spark guard screens and some epoxy to make the insides water
    	   resistant.
    	2. A Marine alternator by Balmar.

    The cost between the two is about $200.

    And while we are on the topic of battery charging...

    Is there any real advantage to buying a battery charger vs. using the
    alternator?  Practical Sailor implied in an article I read that a
    battery charger will increase your battery's life span.  Anyone know
    why?  If you are swinging on a mooring or sailing around and visit shore
    power only once in a while, it seems a good place to save $500.00.

    On the subject of batteries; I know a guy who uses small 6V batteries
    connected together to produce 12V (is that in series or parallel?).
    Is there any advantage to using more smaller batteries vs. fewer
    large ones? Ease of moving the units is the only one I could come up
    with.
    
    I hope that's not too many questions for one note,
    
    Thanks,
    Mark
    

    All depends.  
    
    Battery charger:
    
    If you're on a mooring, why bother installing a charger?  If you're
    looking for a trickle charge, why not a solar panel?  If you're looking
    to spend a lot of money, how about one of those Heart Interface
    combination units that charges your batteries, inverts your DC to AC?
    
    Alternator:
    
    By ALL means, change your alternator!!!!!!!!
    
    Gasoline fumes and the little sparks at the brushes of an alternator
    are a very interesting combination.
    
    Unless you're running a refrigerator or run a CRT radar in transmit
    mode all day long, you  can probably get by on a 50 amp alternator and 
    have most of the power you'd need for typical weekend cruising.  I have 
    a 55 Amp Motorola that keeps two 90AH batteries happy.  Of course, I
    intalled a regulator controller. 

re .9:

Battery and charging systems are rather more complex that you might 
think. I'd suggest that you start by reading the many notes here in 
SAILING (see Note 3.18 for a list) and a basic electrical systems 
textbook. Cruising Equipment and Ample Power (both in Seattle) are the 
two primary vendors of sophisticated charging and control systems in 
the US. The Ample Power folks have published a book titled "Living on 12 
Volts with Ample Power" (or something close to this) that you might find 
worth reading. 

The best system for you really depends on how you use the boat and what 
your electrical needs are. A basic marine alternator and two deep cycle 
batteries may be all you need. Relatively cheap as boat stuff goes. At 
the other end of the spectrum would be a really elaborate system that 
could easily exceed $10 000. A simple upgrade from a standard 
alternator/regulator to a basic sophiscated system (high output 
alternator, multi-stage regulator, digital voltmeter/ammeter) is $750 or 
more. 

    Another book that I would recommend is:
    
    Your Boat's Electrical System by ??????
    
    Brian
    

        Last October on a Tuesday evening, while WINDSONG was minding her
        own business and quietly swinging on her mooring in Beverly
        Harbor and her devoted master was sitting in Lexington High
        School attending a US Power Squadron class on Marine Electronics,
        a rather severe thunder storm passed over the harbor. 
        
        The good news was that TIANA, a 53 foot Swedish built sloop with
        a 60 foot mast was on the next mooring.  
        
        The bad news was the TIANA's mast had been unstepped the prior
        Saturday in preparation for being hauled.
        
        SOOO, WINDSONG's mast was now the highest thing for quite a
        distance and a lonely bolt of lightning decided that it would
        make a friendly path to the water!
        
        I have nothing but praise for the following:
        
                Jubilee Yacht Club for quickly hauling WINDSONG after I
                        had discovered the 'cooked' VHF and water on the
                        wrong side of the hull the following foggy
                        Saturday afternoon. And for allowing me to
                        pressure wash the hull after normal hours and
                        leaving her in the travel lift overnight until I
                        could return the next morning with the trailer.
                
                BOAT US Marine Insurance for covering all related damage
                        with out question.
        
                Dan Rutherford of Ocean Marine Specialties (BOAT US's
                        Surveyor) for very prompt and helpful response.
                        Dan called me at the yacht club 35 minutes after
                        I had called BOAT US (Saturday) and was on site
                        the next morning (Sunday) at 8 AM to not only
                        survey the damage, but assist me in unstepping
                        the mast and securing the boat for trailering.
                
                Lakes Region Fiberglas in Laconia NH for being so easy
                        to deal with and doing a great job of restoring
                        WINDSONG's hull and coordinating the extensive
                        electrical repair work.
                
        Long intro to my question.
        
        Every thing will be done shortly except the:
                 'Testing of the Johnson 9.9 Sailmaster's charging Diodes
                  and electrical system.'
        
        Since I have the motor at the house in Lexington, I plan to have
        it tested locally or possibly do it my self.
        
        When I arrived at the boat and discovered the damage, I was able
        to start the engine with its electrical starter using a 5 year
        old Die Hard (Which is being replace by the insurance). What I do
        not know is if the alternator/ charging circuits have been
        damaged.
        
        I would appreciate any info on how I might do the testing my self
        and also recommended service shops that would do the testing. The
        insurance has allocated an hour of labor to have this done.
        
        Thanks
        
        Fred

    I would guess, but some other may have a better answer, that a simple
    voltmeter would show a rise in voltage above the battery voltage after
    the engine starts.  My previous boat had a Honda Outboard with a 60watt
    alternator that pumped it up to 13.9vdc when running.
    
    I've never heard of a diode that was partially fried.  So if you get
    the volts you should get the current.
    
    

    >I've never heard of a diode that was partially fried. So if you get
    >the volts you should get the current.
    
    Not quite- yes, the diodes are all or nothing, but there are 6 diodes
    in an alternator. They are three phase windings and it takes 6 to get
    all the phases rectified. It is possible one or more diodes are out,
    thus reducing the total current capability.
    
    But, its not very likely that lightning would get one and not the
    others, so I would think if you see a charging voltage you are likely
    OK. 
    
    Even better would be to place an amp meter in the circuit and measure
    actual charging current. The best method is to also have a dummy load
    and crank on the load and measure the max charging current.
    
    

    	I don't really know if this is relavent to this conversation, but
    I have heard of and seen many a diode partially fried. We call it
    leakage and I've also seen low breakdown voltages. The image that 
    popped into my mind though, which neither of these two modes of partial 
    failure describe is the soft knee. On an I/V curve tracer, rather than
    a crisp current flow at the specified voltage there will be a gradual
    increase in current as the voltage goes up. This is a state often seen
    in marginal ESD failures. I rarely see this state hang steady for one 
    more zap, but I have seen a progession through several zaps until
    complete failure.
    	There's also corrosion failures, which occur and NaCl humidity is 
    a wonderful environment to promote that. That would propagate itself in a
    more resistive maner, resulting in heat and less current flow. 
    
    	Sorry, Semiconductor Failure analysis is what I do so I can afford
    to sail. I have seen MANY partially failing diodes. As for corrosion,
    I have had to replace my Loran antenna active load due to an extensive 
    corrosion failure.
    
    Geoff
    
    I want a wind generator! How much did that thing cost you, where'd you 
    get it?
                                                 

    RE: Johnson 9.9 Diodes
    
    Our previous sailboat had a 9.9 Johnson outboard motor.  At one point I
    noticed that the battery didn't charge up as I thought it should.  I
    removed the diode assembly and checked each one with an ohm meter and
    found that some were open thus reducing the charging current to the
    battery (it may have been one leg of the bridge rectifier).  A similar
    check of your diodes will give you the answer that you are looking for.
    
    Regards,
    
    	Howard                              

    Some alternator questions.
    
    What is the typical voltage at the field terminal of an alternator?

    What would 8.5v do between the field and gnd of an alternaotr? Would it
    tickle it enough to get started? If that were the only power to the
    field would it sustain power out?

    I have a T-MAC controller that when tested (disconnected from circut)
    produces 0. to 8.5 volts across a 10 watt load from the terminal
    that's supposed to connect to the field. This seems low. For the field
    connection, I would expect a nominal 12-13 volts with varying current.
    Is this right?

    The reason i looked at the charging circuts to begin with is that
    playing with the reostat on the T-MAC doesn't change the charging
    current, as if the T-MAC had no effect at all. The T-MAC is in parallel
    with a seperate "normal" regulator which is i presume is the one
    actually providing the field power (and controlled alternator output)
    in this case.

    Are fancy (or not so fancy) alternator regulators just current limited
    power supplies for the field terminal of the alternator and whose
    current is based on the alternator output voltage?

re .18:

I made a simple variable output alternator by simply inserting a big 
rheostat in the lead from the batter to the field terminal. It's been a 
while (years), but as I recall, the voltage drop across the rheostat was 
several volts. 

I'd expect that the regulator provides a varying field voltage (which 
results in a varying field current) to provide a fixed output voltage. 
The field voltage could well be in the 0 to 8.5 volt range. The higher 
the field voltage/current, the higher the alternator output current at a 
given output voltage.

When you say the athe T-MAC controller and regulator are in parallel, do 
you mean that both are connected at the same time? I would assume that 
it should be one or the other, but not both. 

Alan

    Quick note response while waiting for a build.

    I guess the 0 .. 8.5 volts makes sense. I somehow expected a full 13v
    and a current limited supply for the field, but varying the voltage
    should accomplish the same thing.

    The T-MAC and separate regulator are in parallel, always connected
    together by design (theirs). The idea behind this is that the T-MAC
    controls the alternator output until a switchover occurs (user
    settable) at a set output voltage. At this switchover It then turns off
    the field power thus "transfering" control to the standard regulator.

    I have "played" with the output of the standard regulator (a red
    transistor thing) and that may have upset what must be a delicate
    balance between the two components performing the same function.

    I am going to play with the two settings (the T-MAC cuttoff and the
    standard regulator adjustment screw) next weekend and see what
    happens.

    One possibility is that the alternator is not a 90 but rather a 55, in
    which case the observed max of about 35-40a is about all i can expect i
    guess. Maybe i'll try a temp rheostat regulator and see what happens.

    All this to avoid dropping the bucks for a amp-hours+II
    meter/controller.

    tnx,
    paul