[C320-list] Alternator to batteries

[Graeme Clark]

Yes indeed, sorry for the confusion - the current through the regulator would be too large if it was in that line, my apologies!
But i think its academic as the regulator is almost certainly integrated into the alternator from 1990’s onwards

Graeme


> On 27 Mar 2017, at 13:00, Scott Thompson <surprise at thompson87.com> wrote:
> 
> Graeme, this isn't quite right. The voltage regulator regulates the relatively small current to the field coils, which thereby regulates the larger output from the alternator indirectly. But the voltage regulator is not connected in series with the alternator output itself. Read the Wikipedia article again and you will see what I mean. I also checked this in Calder and in the wiring instructions for my Balmer ARS-5 voltage regulator. The voltage regulator does not carry charging currents directly and requires only low current wiring.
> 
> Rather the alternator output goes directly to the batteries, often through the same cable used to power the starter motor. (This is the case on my boat.) With this setup the same heavy cable powers the starter motor when starting and charges the batteries when the engine is running. The alternator output connects to this cable at the starter motor. It's a very common arrangement.
> 
> Scott
> 
> 
> On 3/27/2017 7:15 AM, Graeme Clark wrote:
>> Ted
>> 
>> At a risk of teaching grandmother to suck eggs, it might be helpful to understand how an alternator works (basics). Apologies if you are aware of all this already!
>> 
>> This is a simplified explanation -  the wikipedia page https://en.wikipedia.org/wiki/Alternator_(automotive) <https://en.wikipedia.org/wiki/Alternator_(automotive)> is quite useful too
>> 
>> Essentially in order to generate an electric current you need to move a wire through a magnetic field.
>> The current generated in a single wire is tiny so there are many many coils of wire wound together
>> In a dynamo, or generator, the magnetic field is produced by permanent magnets
>> In an alternator the magnetic field is produced by a (separate) electric current through a set of ‘field coils’
>> Thus the alternator needs a minimum of three connections going to it: The positive wire to the field coils, the positive wire  from the current generating coils, and a negative or ground wire - although as mentioned previously sometimes the negative connection is made through the metal body of the alternator being bolted to the metal body of the engine, which is itself connected to ground.
>> The stronger the magnetic field, the more current produced
>> The faster the wires move through the magnetic field the more current is produced.
>> Generally though the speed of the alternator is fairly constant on a boat, but the field coils are fed from the battery, which is being charged by the alternator so in theory as the alternator starts to produce more voltage, the field gets stronger and it produces still more voltage and so on ; - hence the need for a voltage regulator in the circuit. This will ensure the voltage does not exceed a fixed value.
>> The voltage regulator sits on the output side of the alternator, ie it regulates the voltage going to the battery.
>> As has been said there may be a fuse in the circuit - in the event the regulator fails or there is some other short circuit this will protect your batteries.
>> So the potential weak links in the system are:-
>> Are the filed coils getting a voltage?
>> If so is the alternator outputting a voltage when rotating?
>> If so are you getting a voltage out the other side of the voltage regulator?
>> If so is the wire between the alternator voltage regulator and the battery connected, unbroken and all fuses intact?
>> 
>> The final ‘gotcha’ on this is that most modern alternators have a voltage regulator built into them, rather than it being a separate item.  So it may not be possible to test the individual parts as described above
>> 
>> Hope this helps (until you get a copy of Calder’s book!)
>> 
>> Regards
>> 
>> Graeme
>> 
>>> On 26 Mar 2017, at 22:03, Ted Harrison <tharrison at innovations-plus.com> wrote:
>>> 
>>> Thanks Warren. I love to tinker on my boat and I will be making a purchase.
>>> 
>>> Ted
>>> 
>>> Ted Harrison
>>> 
>>>> On Mar 26, 2017, at 4:33 PM, Warren Updike <wupdike at hotmail.com> wrote:
>>>> 
>>>> 1. You don't want to pay $100/hr for a marine electrician or engine mechanic
>>>> 2. You find working on your boat part of the pride/challenge of ownership
>>>> 3. You have time to devote to your boat maintenance
>>>> 4. You like to learn
>>>> Then, go to Amazon and search " calder boat maintenance" and make the best $35 investment in your boat with Calder's "Boatowners Mechanical and Electrical Manual." If it's electrical, electronic, or mechanical, Nigel covers it in this book with how it works, why it doesn't work, how to test it, and how to fix it. With care, study, and preparation YOU can do most things on your boat.
>>>> 
>>>> If engines and motors are strangers to you, find someone you know to help you in diagnosing a problem.
>>>> 
>>>> Every boat can be different even from the same manufacturer, so you have to have some idea what to expect. It's possible that your alternator ground is through the case of the alternator and through its attachments to the engine block. It could also be a separate connection on the alternator with a wire to ground. The positive cable will always be on a connector on the alternator. This positive cable may go to the positive connector on the starter. That will take the alternator output to the selected battery bank. The other connections on the alternator are for control of the alternator. Nigel Calder will explain all this and show you how to test each setup. You must know the dangers as well as the procedures. Improper contacts with battery cables can melt/weld tools... and hurt you too.
>>>> 
>>>> Warren and Pattie Updike
>>>> 1994 C320 "Warr de Mar" #62
>>>> Middle River, Chesapeake Bay
>>>> 
>>>> -----Original Message-----
>>>> From: John Meyers [mailto:jcmeyers7 at gmail.com]
>>>> Sent: Saturday, March 25, 2017 8:14 PM
>>>> To: C320-List at catalina320.com
>>>> Subject: Re: [C320-list] Alternator to batteries
>>>> 
>>>> Thank you for that important education.
>>>> 
>>>> I am still not an electrician but now I know more.
>>>> 
>>>> John Meyers
>>>> 
>>>> On Mar 25, 2017 8:01 PM, "Stephen Cox" <scox at timmin.com> wrote:
>>>> 
>>>> 
>>>>> I am no electrician so I don't know if this will work. I
>>>>> assume that there are wires from the alternator directly to
>>>>> the battery(?) If so can the positive wire (maybe the
>>>>> negative wire too) be CAREFULLY disconnected from the battery
>>>>> after the engine is running and have a volt meter test the
>>>>> output on those disconnected wire?
>>>>> 
>>>> DO NOT DISCONNECT THE WIRES WHILE ENGINE IS RUNNING!!!!
>>>> 
>>>> First off you don't need to disconnect the wires to measure the voltage on
>>>> them.
>>>> 
>>>> Secondly, if you run the alternator without a load it is equivalent to
>>>> switching the 0-1-2 switch through the 0 position when running and will most
>>>> likely fry the alternator diodes.
>>>> 
>>>> 
>>>> 
>>>> Stephen Cox
>>>> Tegwen #1141
>>>> 
>> ———————————————————
>> I work irregular hours and often write emails late in the evening and at weekends; that doesn’t mean I expect you to do the same; reply when convenient!
>> 
>> 
>> 
>> 
>> 
> 

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I work irregular hours and often write emails late in the evening and at weekends; that doesn’t mean I expect you to do the same; reply when convenient!