Conference unifix::sailing

    Well, if you don't know about electricity etc then let's look at
    some very simple and cheap solutions for starters.
    
    1. Preventing drain.
    What you need here is what's called a "blocking diode". This allows
    current to only flow in one direction, ie *into* the battery. You
    need one rated at least 25% higher than your maximum output current
    for safety and preferably 50%.  You can buy them in any good chandlers
    or even in trailer accessory shops very cheaply.
    
    2. Without blowing fuses etc.
    The problem here is that with just the rectifier in circuit you
    still get peaks of voltage that can exceed the input voltage of
    your electronic equipment. A very simply way of removing these peaks
    is to put a darn big capacitor across your rectifier (between the
    rectifier and the blocking diode).  I don't know what units capacitance
    is measured in the US these days but I'd suggest the equivalent
    of a 10 to 20 thousand microfarad at 50 volts DC working should
    take out the ripple and the spikes.  When you've done this, put
    a voltmeter across the rig when it's running on load and check you're
    no higher than about 13 to 13.5 volts - anything more will damage
    your gear. If it's over 14 volts, then you'll need a regulator set-up,
    but it shouldn't be as the Mariner output is designed to be about
    12 volts rms for running lights etc, so by the time you've rectified
    it, blocked it and maybe current limited it you should be ok. If
    not, get more specialist help!
    
    3. Not over charging.
    This is much more difficult, but an easy way is to firstly check
    the current running out of your charger set-up into the battery
    using an ammeter. If it's less than 2 or 3 amps then I wouldn't
    worry about it too much as you're unlikely to be running the charger
    for periods longer than a couple of hours or so, right? If it's
    up at 10 amps then you've got a problem, the easiest way of fixing
    this is to use a resistor to limit the current. You can calculate
    the drop in current you need by using Ohm's law (resistance needed
    equals voltage divided by drop in current required). This is very
    approximate.
    
    Now, I can hear all those design engineers out there tearing their
    hair out! But I can asssure you it works - it's near enough the
    set-up I've got for taking mains off the dockside and running the
    gear whilst charging the abttery at the same time, and it's not
    given me any problems for almost 10 years. The other big plus was
    that the whole set-up cost me less than $5 at the time and shouldn't
    go to more than $25 even today.
    
    Brian

    
    Brian,
    
    If, at the end of my next week's cruise the tape player is still
    in tune and the beer is cold and cards can be played under the lights
    I will be eternally grateful.
    
    	       		Thanks again,  Phil.

    
    My battery charger contains clear instructions about stopping if
    the battery begins to "boil".  The problem is that it doesn't take
    very long for this to occur, and if I were to stop and start each
    time it started to "boil" it would take months to charge the
    battery.  
    
    So I make sure it's filled with distilled water and let it percolate
    for a few hours, stop, let it settle for a few days, and then repeat.
    From what I have gathered elsewhere in this file this is probably
    shortening the life of the battery, but this has been my procedure
    for the last 3 years (the batteries are 6 or 7 years old), and the
    batteries are still going pretty strong.
    
    Is there a different/better procedure I should use?
    
       - Jim
    

    
    You should get a Hydrometer  to measure the specific gravity
    of the electrolyte.  With that you will be able to tell at what
    point the battery is fully charged.  There is no point trying to
    charge the battery beyond the full charge point.  You should be
    able to get a hydrometer at any autoparts store.

    
    I've got a hydrometer, and it shows improvement in specific gravity
    when i let it bubble.  When I'm done it has (and holds) a good charge,
    but since the charger mfg. warns about not letting it bubble I'm
    a little worried that I'm shortening its life.  
    
    Why would allowing a charging battery to bubble shorten its life,
    assuming that there was plenty of water in it?
    

RE: .5,

>>>    but since the charger mfg. warns about not letting it bubble I'm
>>>    a little worried that I'm shortening its life.  
    
Just wondering:  Could the manufacturer be more concerned about liability 
in case of an explosion resulting from unvented hydrogen build-up, than 
about shortening battery life?  If it doesn't bubble, you don't make H2. 
Incidentally, you may also not charge it fully ;-). 

J.

 My charger acts like this:
    
    Using my 8 A charger my batteries "bubble" (is that boil?) after
    about 4-5 hours charge time.  Never does the charge current go above
    6 amps.  At that point they are taking about 4.5 amps charge rate.
    They then slow down to about 2 amp and take another 10-24 hours to get
    a full reading with the hydrometer.
    
    These are 120 amp hour deep cycles. (small)

    Has anyone out there ever tried one of the regulator bypass systems
    like the one from Spa Creek?  From my understanding, this would
    allow a stock alternator to deliver increased current to the batteries
    for as long as needed to fully charge them.  My concern would be
    that bypassing the regulator could fry the batteries in no time
    flat unless you closely monitored the charging or the system has
    some sort of sensor that would automatically cut back the juice.

re .8:

Several problems here. First, stock alternators will not deliver their 
rated output for any length of time (more than a few minutes) without 
self-destructing from overheating. I don't know how much derating of a 
stock alternator is necessary, but I'd guess on the order of 50%. Using
a regulator bypass to increase charging current could well destroy your
alternator (as well as your batteries).

Second, yes, most batteries will take a higher charging rate than 
provided by the standard alternator regulator. But, higher charging 
rates mean increased gassing (that's not boiling that's been mentioned 
previously -- it's oxygen and hydrogen gas being released from the 
battery), which increases the possibility of a nasty explosion. 

Past a certain state of charge, high charging rates are damaging to a 
battery. State of charge is easily measured with an good voltmeter 
(eg, a digital voltmeter with an accuracy of 0.5% or better -- the 
usual analog and LED voltmeters aren't anywhere near accurate enough). 
Once that state of charge is reached, the charging current should be 
drastically reduced.

High charging rates can also greatly increase battery temperature. I 
don't recall what unpleasant effects this has.

As I've mentioned before, a couple of companies (eg, Ample Power and 
Cruising Equipment) manufacture sophisticated charging systems. Read 
their literature for an education in battery charging. It isn't simply a 
matter of driving amperes into a battery. These systems are expensive 
(well over $500 up to a few thousand dollars). After reading about them, 
I've decided that until I can afford one, I'll stay with the stock 
alternator and regulator as being adequate, reliable, and relatively 
immune for operator error.

    
    re .9:
    
    obviously it's not really boiling, that's why "boil" was quoted.
    
    if we had a very accurate VOM and a highly adjustable current
    source, what would be the recommended charging schedule, i.e.
    what does the battery voltage vs charger current curve look like?
    
       - Jim
    

    re: ideal charging schedule
    
    The "Ample Power Company" mentioned by Alan in a previous note is
    owned by a live aboard couple.  In addition to selling 12 and 24
    power system components they have also published a book, "Living
    on Twelve Volts With Ample Power".  I got this book from the Dolphin
    Book Club and highly recommend it.
    
    If you never buy any of their products or do anything to your system
    you should have this book anyway.  It is the most complete treatment
    of rechargeable batteries I have ever read (and I'm EE so have read
    some).  Anyway, I have loaned this book out so don't have exact
    terms and numbers in front of me so take all of the following as
    suspect until I can get the book back.
    
    There are four distinct cycles to the ideal schedule.  The first
    cycle is a brute force dump of as much current as your alternator
    and wiring can withstand, limited only by the temperatures generated
    in your battery.  
    	*** Note that standard alternators can't do this ***
    Not surprisingly they sell high output alternators that can do it.
    We're talking in excess of 50 amps for more than an hour.  I think
    this is left on until the current drops below approx. 10% of the
    Amp-Hour rating.
    
    The second cycle is a constant voltage cycle (I don't want to quote
    the number and mislead 'cause I'm fuzzy on this).  The constant
    voltage is left on until the current has dropped below something
    like 3-5% (again I'm fuzzy on the number).  This gets you to about
    85% of the battery's true capacity.  Also it's important to note
    that all but the most sophisticated systems are compromises and
    they compromise on this scheme [constant voltage].  There are two
    reasons for this; it's cheap, it's idiot proof.  This phase might
    take 4-5 hours.
    
    The third cycle consists of a constant current on the order of a
    few hundred milliamps.  I don't remember the length of time here
    except that it seemed to me to be quite long (days).  This gets
    you to 100% of rated storage capacity.
    
    The fourth cycle is a maintenance cycle which is on the order of
    milliamps and is left on forever.  The sole purpose of this phase
    is to counteract leakage currents that eventually drain unattended
    batteries.
    
    The company sells regulators which replace the normal built in
    regulator that will semi or fully automatically reproduce this
    scenario.  They are not cheap ($300.00) and my conclusion (based
    on my personal requirements) is that I will settle for the 85%
    compromise until I buy a Valiant 40 and go for it :^).  In order
    to fully reproduce this schedule you would need auxiliary power
    generation gear to complete the latter (time consuming) stages of
    the cycle.  They sell (surprise) solar, wind, water equipment to
    connect to their regulators for just this purpose.
    
    What I am trying to get to for my own schedule is a high output alternator
    that can do phase 1 without frying, followed by a constant voltage
    cycle for phase 2.  At that point I think everyone but liveaboards
    will have most of their needs met.

re -.1:

My memory of the Ample Power literature is somewhat different. No 
battery should be trickle charged indefinitely (as I recall). The 
charging phases are, if memory serves correctly:

1. bulk charge (at a high rate) until some charge level is reached

2. charging at a lower rate (like at a current equal to one tenth the 
amp-hour rating of the battery) until some higher charge level is 
reached

3. constant voltage charging as long as there is a load on the battery

4. occasionally (eg, monthly) charging the battery to a very high 
voltage (over 16 something volts) that risks damaging electronics 
if they're turned on.

The Ample Power systems do 1, 2, and 3 automatically. Step 4 is done 
manually. One of the whole points of the Ample Power system is that it 
allows batteries to be recharged much more quickly than with a 
conventional constant voltage regulator. The Ample Power (and other) 
alternators can supply over 100 amps continuously (which, by the way, 
requires something like 2.5 engine horsepower -- it only takes maybe 8 
hp to push my 12000 lb boat 5.7 knots in calm seas). If you have a 
mechanical refrigeration system (eg, Sea Frost) you can cool the icebox 
and charge your batteries with quite minimal engine running time (1/2 to 
1 hour per day). 

But, yes, a full blown system (regulator, voltmeter, ammeter, batteries, 
solar panels, etc) could easily be $2500. When I leave for my 
circumnavigation, I'll have one. Until then, I'll depend on my Lucas 
(Lord of Darkness) alternator.

    re: .12 memory alert
    
    Yes Alan, I could be totally off base in my .11.  Anyone who values
    their electrical system should get the book and not rely on my hazy
    recollection.   My main point in conveying .11 was to point to what
    I consider a very well written and reputable source.  My secondary
    reason was to *broadly* show that this is not as trivial a subject
    as the battery and alternator mfg. would have us think.
    
    By the way, I've been told that there are high output alternators
    made for things like police service.  Does anyone have knowledge
    on this?  Does anyone know if it's feasible to put this kind of
    alternator into marine service?  The only alternators I have seen
    are >$280.00  and it sure would be nice to get that price down some.
    

High output alternators for police vehicles may simply be high output at 
idle (gotta keep those blue lights flashing while Smokey writes your 
ticket) or they may be simply higher output than what us folks usually 
get with our cars. They may not be capable of continuous very high 
output (eg, 100 A). 

In one of the electronics mags a few months ago, I saw the introduction of
(or at least reference to) a complete battery charging control chip. You
use resistors to set trigger points and charge rates at the various stages
based on battery manufacturer's specs. You used it to controll pass
transistors, etc. I don't remember manufacturer or price but I think it
was under $20.00.

    
    I finally took the good advice of some of the noters who posted
    earlier replies to 825.0 and read the book "Living on 12 Volts
    with Ample Power".  I also called Yamaha and asked them for some
    details about my alternator and its usefulness for charging
    batteries.
    
    What I found out was that the alternator puts out a nominal
    12.0v, and according to the manufacturer, "is not really intended
    for battery charging".  (This came as a surprize at first, since
    this contradicted the salesman/owner who sold me the engine).
    With a 12v source, you're not going to charge a 12v battery very
    effectively, and the high amps that the engine puts out could
    definately do more harm than good if the battery already has
    a good charge.
    
    What I'd like to do is modify my charging system to provide a
    reasonable level of performance without spending a great deal
    of money, e.g. by buying a portable generator and expensive
    regulators, unless that is the least expensive alternative in
    the long run.
    
    The engineer at Yamaha suggested replacing the alternator pulley
    with a larger one (13.8/12.0 larger circumference?) to generate
    a higher voltage output.  All my electronic equipment is spec'd
    to operate at this level, so maybe that could be an inexpensive
    first step.
    
    Do the alternators of most (non-Yamaha) engines put out a higher
    voltage, or is 12.0v alternator output typical?  How do other noters
    who rely solely on their engine for in-season battery charging
    ensure that their batteries get properly charged?
    
       /Jim
    

>    The engineer at Yamaha suggested replacing the alternator pulley
>    with a larger one (13.8/12.0 larger circumference?) to generate
>    a higher voltage output.

	If the output voltage is really sensitive enough to rpm to
have a slightly larger pully work, why don't you just run the engine
13.8/12.0 faster?  It seems that if the alternator was that sensitive,
the output voltage would be all over the place when you go from idle
to cruising speed.  Thats what voltage regulators are for!!!!

	I plan to check my batteries every time I get on board after
a rest period (>= 24hours) and record the voltage.  I have a laminated
copy of the voltage/charge % chart from the ample power book on board.
I can atleast keep track of battery charge trends.

	Checking the charging voltage is going to be real early on
my spring commissioning check list!!

	Dave

    Is the 12 volts from the published specs or did you actually check it
    with a volt meter?  If you did use a VOM, did you check the reading
    over a range of rpm?  At lowest idle you may get just 12 volts but at
    2000 rpm I'd be surprised if it wasn't 13+, especially if you take the
    reading just after starting the engine when the battery is being
    replenished.  Also, the reading from a digital VOM is more reliable
    than that from an analog one.  It can be awkward intepolating between
    the lines since the relevant range is only about 1.5 volts.
    
    12 volts with the engine running usually means they're not coming from
    the alternator.  It's probably all coming from the battery.  The
    alternator isn't doing anything.  And I'd worry about the battery too. 
    You should get slightly more than 12 out of a battery with a reasonable
    charge.
    
    If the 12 volts is real, it's maybe time to check out the alternator. 
    Check continuity in all wires, the condition of the brushes, continuity
    in the slip rings and diode bridge.  It could be something as silly as
    a loose belt.  That one happened to me when I changed a water pump
    impeller and neglected to adequately tighten the drive belt when I was
    done.
    
    I'm surprised at the salesman's comment about the charging capabilities
    of your alternator.  The trickle charging systems on some not-so-large
    outboards put out a modest number of amps but it still has to be at
    greater than 12 volts.
    
    - gene

    
    re: .17
    
        I agree with you, the suggestion of increasing the size of
        the pulley doesn't make much sense.  First of all, wouldn't
        that affect current but not voltage?  Secondly, if it's the
        pulley on the alternator itself it should be smaller, not
        larger.
    
    re: .18
    
        No, I haven't measured the charging voltage with a VOM yet,
        but like .17 I plan to make it part of my spring commissioning
        checkout.  I guess it's time to get a digital VOM.
    
        The 12.0 figure comes from Yamaha rather than from measuring
        the output voltage.  According to the engr. I spoke with the
        output current varies from 10A @ 2400rpm to 13A @ 4500rpm, but
        the voltage is controlled at 12.0v independent of rpm.
    
        re: salesman's comments -- I suspect that the salesman assumed,
        as I did, that the voltage was sufficient to charge the battery.
        The usual glossy promotional brochures contained no information
        on output voltage.  btw, the salesman/owner sold out and left.
    
       /Jim
    

>        The 12.0 figure comes from Yamaha rather than from measuring
>        the output voltage.  According to the engr. I spoke with the
>        output current varies from 10A @ 2400rpm to 13A @ 4500rpm, but
>        the voltage is controlled at 12.0v independent of rpm.
    
Is this the same engineer who told you to put a different pulley on it?
I think all this "info" from yamaha is suspect. 

  o  An alternator puts out AC, which is fed through a rectifier and a
     voltage regulator. The output voltage is always limited by the regulator.
     You cannot increase the output voltage beyond the regulator's design
     voltage without modifiying the regulator. (When the engine is running
     at idle, the alternator may not put out enough voltage to drive the
     regulator to its designed output voltage.)

  o  "All" "12V" alternator systems regulate to approx. 14V. They are typically
     designed for "float" charging a fully charged battery, while supplying
     adequate current for other equipment, i.e. the ignition system of the
     motor + aux equipment. They are not very effective for charging discharged
     batteries, because these batteries can be charged faster at a somewhat
     higher voltage. Although the regulators could be set to a higher voltage
     to do fast charge, the manufacturers don't set them up that way because
     it will overcharge the battery after the battery is fully charged.
     More sophisticated chargers are available. These gizmos sense when the
     battery is almost full, and reduce the charging voltage to prevent
     overcharging.

--RS

    I was told that one way to charge dead batteries quickly and to run all
    other equip efficiently was to replace 
    the engine alternator with one I could pull off a fully loaded cadillac
    from a junk yard. Evidently, they are the 100 amp variety. The theory
    behind this was it would supply tremendous current output for all your
    usage needs and allow the batteries to charge. Any truth to this?
    
    Another question: the previous note talks about overcharging batteries.
    My shore power charger is boiling my batteries out. Any suggestions on
    how to tone it down? If I can't adjust it, should I not leave it
    plugged in during the week and only turn it on during the weekends I'm
    on the boat? What's the potential damage being done to my batteries?

re -.1:

Using an automotive alternator in a boat is not a very good idea, 
especially if you have a gasoline engine. Marine alternators are 
designed not to cause an explosion from the internal sparking of the 
brushes. Automotive alternators can easily cause an explosion if there 
are enough combustible vapors in the engine room. For the same reason 
don't use an automotive starter motor. 

Proper charging of lead-acid batteries is really quite complex. Get 
catalogs from Balmar, Ample Power, and Cruising Equipment (all in Seattle) 
and read them carefully. The information is somewhat conflicting and 
what you finally believe is a somewhat religious matter. A well-designed 
and implemented electrical system is a really major investment (easily 
$1000 to $3000 and much more). There are some good books available, too. 

One not so small point that Ample Power and Cruising Equipment don't 
mention is that a large V-belt or multiple V-belts are required to drive 
a large (>100 A) alternator. The little 3/8" belt on my engine isn't 
adequate for more than the small alternator (maybe 35A) now on the engine. 
I'm not excited about having to machine a new crankshaft drive pulley 
and make a complex alternator mounting bracket (my lord of darkness 
Lucas alternator mounts differently than the standard US small case 
alternators -- bleah). 

Once your batteries are nearly fully charged (battery voltage has 
reached 14 volts or so at a current of 10% to 25% of the amp-hr 
capacity), the charging current should be reduced to 3% to 7% of the 
amp-hr capacity (ie, 3 to 7A for a 100 amp-hr battery). Too much 
charging current will boil off the water and quickly ruin the batteries.

    
    re: .20
    
        thanks.  I called Yamaha again to check on the information given
        to me on my first call (by Clint Sanders), and this time spoke
        with James Mills.  He confirmed what you had said: that the
        voltage is limited to 14v, not 12.0v.  Phew!  I guess the lesson
        here is to use common sense and to get a second source of
        information?
    
      /Jim
    
    

I have looked at a number of books and all deal with alternators of the
kind that come with a deisel. I have not seen a single mention of the
kind of charger that one finds on a outboard. These (I'm told) consist
of a magnet attached to the flywheel which induces a voltage in a coil
that is stationary.

I have an 8HP Mariner out-board and have asked the yard to instal a charger.
They tell me the charging voltage is 13.2 V, which struck me as rather
low for the kind charging I need. While cruising I expect to use the engine
as little as possible so the charge on the battery could go up and down
a lot. Hopefully it will charge up quickly!

I expect to use the battery merely for cabin and overnight running lights.

Any experience of this kind of charger?
Mike

re .24:

I'd guess that the output from an outboard motor alternator is fairly 
low (a few amps), especially if the output is regulated to only 13.2 
volts. To know whether or not this will meet your needs you'll have to
estimate how many amp-hours per day you use. An anchor light typically 
draws about 1 amp, so on a summer night it will use maybe 10 amp-hours. 
Cabin lights for a bit of reading will use another 2 to 4 amp-hours. 
Battery recharging isn't 100% efficient -- more like 80%. So if you use 
12 amp-hours, you'll need to return 12/.8 = 15 amp-hours to the battery. 
This is likely to require more engine running that you indicate you want 
to do.

    I had a Nissan 8 horse on my Freedom 21, and had the charging device
    installed.  I was able to run the boat for two consecutive seasons
    without having to use any other charger on the battery.  I kept that
    boat at a slip, so most of the time when I was coming or going I had to
    use the engine, but for the most part I sailed, not motored.  I'm on a
    mooring now, and so I'm not sure I'd use the engine enough to charge
    the battery if I still had that boat.
    
    My primary drains on the battery were a VHF radio, running and steaming
    lights, and the anchor light.
    
    If I remember correctly, the output of the charging coil was in the
    range of 40 watts.  About three amp/hours per hour of running I'd
    guess.
    
    
    djc

    I had a charger installed in my Merc 5 h.p. when i purchased it. Given
    that my needs are quite modest, it has always kept the battery fully
    charged. After not using the boat for a week or two, the charger
    typically puts out around 1.5 amps, and suspect it would top out
    around 3 amps if the battery were really down. When I bought it, I was
    cautioned that it wasn't a "heavy duty" charging system, but for what I
    need, it does fine. (loran / ds/ vhf and occasionally running and cabin
    lights)
    
    Bill
    

    
      FWIW:
    
         Two weeks ago, my depth sounder died in the middle of a race.
    Having seen this before, I had the crew switch to the other battery,
    which resolved the problem. Sure enough, the 1st battery was flat.
    (turned out the halogen steaming/deck lamp had been left on during the
    daylight hours).
    
         The next weekend I was out and the wind died, so I cranked up the
    outboard for a long ride in (about 4 miles). I made sure the dead
    battery was switched on for the charge. Once back on the mooring, the
    battery was still pretty dead. Oh-no, I musta killed the damn thing.
    
         So I yank the batteries and take them home for a real charge. 
    The bad battery turns out to be an automotive diehard ;>( , but it
    does take most of the charge (good enough for the rest of this season).
    The other recharges what little it needs easily. So I get to thinking 
    what is the problem with the outboard recharging the batteries?  Normally
    I can get through the whole season without external help unless we are
    on vacation (using those pesky inside lights and all...).
    
        Pulling the connector between the motor and wiring harness shows a
    tiny bit of corrosion, but nothing major. So for a test I fire up the
    outboard and switch on the depthsounder. Usually it is a bit erratic,
    but it runs, as will the cabin lights. But nothing happens.
    
        So I look at the other side of the connectors and they are green
    with corrosion. It was not worth screwing around with, so I picked up a
    new male/female set and stripped back the wiring a bit before a R&R. Now
    everything runs off the motor again and I have a solid system (not even
    erratic any more).
    
        Moral of the story is that even though a connector looks clean,
    make sure the wire ends are also clean if you want to keep your
    batteries charged. And give them a check as part of you P.M. schedule.
    
        john who just replaced 5 gallons of fuel onboard (since mid March!).

    outboard = 60watts.  (most of the time)
    
    
    Let's see, that means means about 14 hours at full throttle to get a
    half charge.  
    
    you have along way to go (to the races)????
    
    My Yanmar at 35amps (420watts) takes four hours to get in 75% charge.
    On one battery. Ilooked at 75amp alternator but the Yanmar folks said
    don't. unless I want a real slow boat.......
    
    

         You think I let the S.O. bring a blow dryer or space heater
    on board???  :>) ;>)
    
     Actually, we usually only use the depthsounder, vhf, and cd player.
    At night, 3 nav lights plus the compass/depthsounder lamps. The Loran
    is only used when we go out deep or the fog comes in.  
    
      Before leaving the mooring, I always kick the motor over and warm it
    up (3-10 minutes use). Coming back, I always use the motor to anchor it
    (again 3-10 minutes). This is enough to keep the batteries fresh for at
    least half a season, ussually more.  The draw is so minimal, the
    outboard can keep up at 5-20 minutes a sail. Then there are those dead
    in the water days where a 40 minute "ride" back helps top off the
    battery (5 gallons worth so far this year...).
    
      I have a Fluke digital multimeter that is good to 1% of a volt. When
    it gets below 11.5, time to haul the batteries home for charge. I only
    use 1 battery if possible, so that the backup is alway fully charged.
    Only thing worse then a dead battery is 2 of them.
    
    Oh yeah, to get to the race is 15-20 minutes wide open. If it is that
    dead at the start, there is a real good chance we will be doing a 20-40
    minute "ride" home later     ;>(  .

    three nav lights = 36 watts
    
    vhf on standby = less than 10 watts
    
    depthfinder = probably less than five watts
    
    
    but the sound system...oh oh.  If you do not have a amplifier and you
    only crank the music up halfway and there are only two speakers (I have
    four), there goes another 12 to fifteen watts.
    
    60 watts?? for how long? two to three hours.  15amp/hrs out, 2.5 to 3.0
    amp/hrs in.  10 to 12 amp/hrs deficit/day = dead battery in 10 days.
    
    Is this about right?
    

    Yeah and dont those batterys have a memory that wont charge to full 
    if they are not totally discharged?
    
    Joe

    John,
    
    Taking an auto battery to 11.5 volts is really flattening it,
    and auto batteries will only let you really flatten them a few 
    times. 
    
    I recahrge my Die Hard Marine deep cycle when it gets down to 12.0
    volts.
    
    re: later reply - No, its the older nicads not lead acid that
    develop a memory of discharge cycles.
    
    Bill
    

    1. this is a light weight boom box. No real powere here. We only crank
    up the music in certain tactical positions on a race course.
    
    2. Like I said, 5 gallons  of gas so far plus recharging one of 
       the batterys . And this has been since the 2nd week of
       March. About 4 hours on thursdays and 12-14 hrs each weekend.
       
    3. Only one is an automotive battery. The other is a deep cycle marine
       battery.
    

    FWIW, I am able to keep the deep cycle DIe Hard up with the output
    of the charging circuit on my 5 h.p. merc outboard which puts out
    about 1.5 amps. Typical use is daytime with a VHF, LORAN and Depth
    Sounder drawing power. Sometimes also use an old Tiller Master
    autopilot too.
    
    For music, I get many many hours out of a G.E. AM-FM Tape player that
    has its own batteries. 4 C-cells last a long time.
    
    I normally motor at least 10 minutes in and out of the boatyard,
    so there is 0.5 amp hours replaced. 
    
    Last season, I motored enough to keep the voltage in the 80-90% charged
    range. This year, with corroded wiring (that is the next thing to
    be fixed) I had to recharge the battery a couple of weeks ago.
    
    1.5 amps isn't much but if it keeps up with half the amp-hours that
    I consume, it takes a long time to bring the battery down.
    
    Bill
    

Re: 825.35
	Bill,

	How did you get the figure of 1.5 amps output for your outboard.
	Is it from the spec or did you measure it?

	I would like to know the output of my charger but I
	have a digital voltmeter that only measures small currents
	in milliamps.

	Mike

    >  How did you get the figure of 1.5 amps output for your outboard.
    >        Is it from the spec or did you measure it?
    
    I continually measure it. I took the ammeter from a small 3-amp
    battery charger that had died and put in series with the + lead
    right by the battery box. I did it for several reasons:
    
    1. The Merc dealer cautioned me not to expect too much when I
    ordered this option with the motor, so I  wanted to see what I
    really got (initially).
    
    2. With my salt water forays each year, I have had a horrible time
    with corrosion on the connecter outside the motor and outside
    the transom. I really have to get some timmed wire, seal the
    connections well and get them inside the boat. One problem is that the
    pass-thru pipe from the gas can compartment (in the aft of the
    cockpit) is the only pass-thru hole that is handy. I don't want 
    a sparking connection any where near my gas tank.
    
    So now the ammeter also tells me if the charging wiring has corroded
    thru.
    
    A small ammeter shouldn't be expensive (radio shack?). These
    inexpensive battery chargers are pretty innacurate - the rest position
    of the needle with no current moves around by 1/2 amp, but the change
    is around 1.5 amp from no to full current.
    
    Bill
    

You should be able to measure current even with a cheap DVM:

1) Take a piece of moderate guage wire, perhaps 22 guage for
   a 2A charging circuit. It should show about 100-200 mV in step 3.
   Measure its resistance R. It should be a few tens of
   milliOhms or even up to 100 milliOhms.

2) install it in series with your charging circuit

3) start charging and measure the DC voltage V across the
   cable. If you see about 100-200 mV, your answer will be
   valid. If you see more than 200 mV here, the charging current
   may be affected substantially by the voltage drop.

4) The current is I = V/R

--RS

re .38

Yes, but .......

Most inexpensive digital voltmeters (and even some expensive ones) have 
a minimum resolution of 0.1 ohm when measuring resistance. It is quite 
difficult to measure milliohm resistances. I'd suggest looking up the 
resistance of various gauges of copper wire in a reference (say, the CRC 
handbook of chemistry and physics). The resistance is usually given as 
ohms per 1000 feet. Just use whatever length gives the resistance you 
want. The resistance varies somewhat with temperature.

I made a shunt using (I think) a 39" long 18 gauge wire. It has about a
10 millivolt drop per ampere of current. (The length and gauge may be 
wrong, but they're very roughly correct.)

Some inexpensive digital voltmeters have a minimum resolution of 0.01 or
(even worse) 0.1 volt. You'll need a DVM that reads to at least 0.001
volt to have much success monitoring current with a millivolt shunt. A
Fluke 73 DVM (~$75 to $100) works well. 

A cheap ammeters (<$20) may be a better idea if you don't already own a 
suiteable DVM.

Alan

PS The Electronic Superstore in Woburn, MA, sells surplus/used/obsolete
stuff at really good prices. I got a high quality 0-30A ammeter there
for under $10. I also got a 0.01 ohm, 25W, 1% resistor for a couple of
bucks. I use it to measure solar panel output current. 

.38 and .39

	Thanks. I will try to make a shunt for my DVM.

	I have had the problem of corrosion in the connection
	between the outboard/charger and the leads to the batteries.
	It is quite difficult to know when corrosion has set in
	as I can't see the connection.

	Maybe I should install a plug and socket (... but the 
	soldered connections to them can also corrode and still
	are hidden!)

	Mike

	p.s How effective is that 'liquid insulator' stuff that
	looks like tar?

    Excellent stuff. Liquid insulator is far better than electrical tape,
    crimp connectors etc. and turns joints into perfect seals.

    Does it harden or become non-tacky? I hate electrical tape. The
    adhesive never lasts.  
    
    

    We use the liquid insulation tape to finish all our crimped or soldered
    joints. It sets like rubber and completely seals the joint.

    re: .40 et al Corrosion
    
    A bit off the topic, but on Viking Rose I solder all connections after
    crimping, then seal with the liquid tape. This is especially necessary
    for non-tinned wire which will begin corroding under the insulation in
    a salt air environment. Anchor also has a line of wire connectors which
    includes adhesive heat-shrink tubing which also works well at sealing
    the connection. I generally use computer grade connectors bought in
    bulk (at a much lower price than Ancor) at a mail-order electronic supply
    house (ALL Electronics (800)826-5432).
    
    Howard

    wire connectors which
        includes adhesive heat-shrink tubing
    
    Not bad, but ridiculously expensive from any source! Simple crimps with
    liquid rubber are easier and a lot cheaper.

    If you SOLDER all the connections you can you will minimize your
    corrosion problems. Radio Shack sells a red rubber like electrical
    tape (expensive stuff!) which you can wrap around the connection/
    connector.  Its a self-vulcanizing type rubber which seals on contact
    with itself. I use this rubber stuff for all critical connections.
    Also I solder ALL connections I can. You can also use products such
    as WD 40 and other water displacing sprays to minimize corrosion
    effects.
    
    Jeff

re .46:

Actually, soldering may not be a good idea. I'm fairly sure that this
has been discussed elsewhere in this file. The solder wicks under the
wire's insulation and makes the wire stiff and prone to breaking from
vibration. Crimped connectors covered with heat-shrink tubing and tinned
wire seems to be the most reliable method. See also some articles in
Practical Sailor. 

re (un)tinned wire:

Clearly, untinned wire that gets wet/damp does corrode quickly. 
Virtually all of the original wiring in our boat, now 16 years old, 
is untinned. About the only wiring failure we've had is a fracture at a 
crimped connector, cheap, no strain relief, not well-crimped, possibly 
corrosion induced since the connection was low on the engine. Otherwise,
our boat is well-ventilated and stays dry inside. 

My practice has been to use tinned wire whenever adding new wiring, but 
I'm not about to rewire the boat just yet. I've also noticed, rather to 
my dismay, that the power cables for some electronics (such as our 
recent Standard VHF) use untinned wire. 

Alan

    I hear what you say Alan about soldering.  I am suprised that a crimped
    connection is not prone to severe corrosion.  Even with heat shrink it
    would be very difficult to get a good seal at the crimped end of the
    wire.  Vibration and breaking: I have never seen it happen on my boat
    with soldered connections.  (maybe I have been lucky).  I do know that
    crimped connections seem to corrode very quickly and if not crimped
    JUST right the wire tends to pull out or create a loose connection. 
    Even if the solder is prone to breaking due to metal fatigue wouldn't
    the wire itself resist breaking as if it wasn't soldered at all?
    
    Well, if studies have been done comparing the various techniques
    (as I am sure they have been done) and crimping wins who am I to argue
    for soldering?
    
    Jeff
    Jeff

    re: last few
    
    I have to agree with Jeff on this one, and take exception to Anchor,
    Practical Sailor and others. 
    
    In many years of building "home-brew" electronics equipment, antennas,
    etc. the rule of thumb is to use crimping (or other means) of providing
    mechanical strength first, then use solder to provide a low resistance
    and corrosion-proof electrical connection.
    
    I believe that a good reason that the "experts" do not advise soldering
    is that most people have neither the skills, tools, or time to do it
    properly. Thus the producers provide to the market-place what works
    quite well for most of the needs. I can not imagine an automobile or
    boat manufacturer being able to afford the time to crimp and solder
    each electrical connection.
    
    Fo me, I am willing to take the extra time to do both and am sure that
    an electrical connection once made will not have to be thought about
    for a good long time. As for vibration causing a problem, I have read
    about it but never seen it happen. On a boat 95% of the electrical
    connections are not normally subject to vibration and therefore are not
    subject to this hypothetical risk. By the way, I do seal all connection
    with either heat-shrink tubing or liquid rubber.
    
    	Howard

I have sailed on a boat which suffered from persistent vibration problems on the
alternator connections. I do not believe that either crimping or soldering would
have made any significant difference, as the basic problem was that all the
flexing due to vibration occurred at the point at which the cables entered the
terminals. The wires rapidly fatigued and failed.

The key fact is the localisation of the flexing. Crimping has a small advantage
here, as it does not introduce a hard spot to quite the same extent as
soldering. However, I would always prefer a well-soldered joint to a crimped
joint for its electrical properties, and crimping followed by soldering sounds
good. However, and especially with a soldered joint where solder wicks into the
strands and causes a hard spot, it is essential to provide some strain relief to
avoid mechanical strain on the joint, and some reinforcement to ensure that all
flexing takes place in the cable itself, not at the joint. Either clamp the
cable just outside the joint, or provide sleeving to reinforce the joint.
Heatshrink might be enough, depending on cable size and stiffness, and that
might explain the success of such joints. Think of the usual way in which an
electrical cable leaves a portable domestic appliance or something like a power
drill. It often has a rubber sleeve, with tapered stiffness to avoid exactly the
kind of localised flexing that I have mentioned above. 

There are both electrical and mechanical problems here, and they have different
solutions!

- Brian (trained in a defence spec wiring shop, where we even used to clean the
gold off transistor pins before soldering to avoid the effect of soldering with
a gold/solder alloy, which is prone to failure, and all soldered terminal
connections were fitted with rubber sleeves (pre-heatshrink days!))