See annotations in [brackets].
Norm
S/V Bandersnatch
Lying Julington Creek
30 07.695N 081 38.484W
> >
> >
> > __
> I agree with Arild. Use the factory schematic. I was surfing the web
> wrt alternators the other day and came across an article describing how
> to wire a 10SI Delco alternator. It was patently incorrect, so if you
> are using the web as a resource be sure to get more than one opinion.
>
> Here's a typical alternator hookup. You will have up to 5 connections.
>
> Ground. Most alternators have a terminal on the case that should go to
> ground. Don't rely on the mounting bolts to provide ground. They
> sometimes don't. It's been my experience that faulty grounds are one of
> the most troublesome problems, because people tend to overlook the
> ground connections. This is true in cars, motorcycles, boats and
> electronic, not to mention house wiring.
>
> Output. This terminal can usually be identified by being the one with
> the biggest wire connected to it. It is often an insulated stud
> connection not associated with any other wires. It is highly
> recommended that this wire run directly to the battery or to another
> connection that is tightly connected to the battery, such as the hot
> side of the starter.
> Many installations have a large wire directly from
> the battery to the starter and I've seen the Output from the alternator
> go to this post also. That's a good place to connect it if you have the
> starter circuit running through a battery disconnect switch. (Which I
> don't recommend for larger engines).
[I don't understand this. The output of the alternator must not have its
load removed while operating or the output diodes will be destroyed so
connecting it to a battery via a switch that could disconnect it from the
battery is a no-no unless the switch in question has a field disconnect
switch in use.]
> Field. This is the wire that must go to a switched ignition. It
> provides the exciting current [about 5 to 6 amps] to the alternator field
circuit and will
> draw current so it must be disconnected when the engine is not running.
> It is highly recommended that this switched ignition be of the type that
> is disconnected when the starter is engaged. On common automotive
> switches there will be two switched ignition terminals, one will be hot
> any time the switch is on, and the other will be hot only when the
> switch is on and the starter is not engaged. On smaller engines the
> load placed on the alternator can be large enough to prevent the engine
> from starting easily. I've not experienced this but I'm told that it
> can be a problem. If the ignition switch does not have the capability
> of providing the disconnect on start, then I wouldn't worry about that
> problem unless the engine is hard to start and acts like it's not
> spinning fast enough.
>
[Some diesel installations do not have an "Iginiton Switch", and such a
switch could be switched on when the Diesel engine is not running. I use a
two-terminal oil pressure switch instead to switch both the alternator
field and the engine instruments/alarms. (I have a Start switch and kill
the engine with a {seperate from the single-lever engine control}engine
speed [basically an idle control]control.]
> Sense. This is a very important wire. This is the feed back to the
> regulator that tells the alternator "that's enough". It needs to be
> connected to the battery. How or where it connects depends a lot on
> your installation. Some solutions suggest that you run it to the Output
> terminal of the alternator. That is probably the safest connection. If
> this wire becomes disconnected or is connected to a location that
> differs greatly in voltage from the Output terminal, you can destroy the
> diodes in the alternator. It usually happens when someone ties this
> wire to a battery that is separated from the charging circuit by a
> battery switch and forgets to close the switch.
>
> A disadvantage of having the Sense tied directly to the Output is that
> there is resistance in the wires between Output and the battery being
> charged. At high currents (lots of batteries, and/or depleted charge)
> this will result in a lower voltage at the battery which in turn will
> necessitate running the engine longer to get a satisfactory charge.
> Running the Sense wire directly to a battery that is always connected to
> the Output terminal but AT the battery or close (electrically) will
> result in getting full voltage to the battery. By "electrically close"
> I mean connected to a point that has a very low resistance path to the
> battery. For example a 3 foot run of 2/0 cable from the starter to the
> battery.
>
> I would suggest that running the Sense line to the same point the Output
> line is connected to is a reasonable procedure.
>
> The last wire you may have on an alternator is the output for the
> Tachometer.
>
> I'm not suggesting that this is a complete document on how to connect
> alternators, it's just one way to do it.
>
> The important things are, switch the Field wire off when the engine
> isn't running. Be sure the Sense wire is always connected somehow to
> the Output anytime the engine is running (not necessarily directly, but
> it has to be at the same approximate voltage for efficiency). And don't
> forget to ground the alternator securely.
[I would add, never disconnect the alternator output from its load when it
is operating.]
[There was some discussion on the List some time ago about the wisdom of
using a switch to disconnect the starter from the start battery to
disconnect the starter in the case of a short circuit fire. The general
consenus, and I can't remember the details, was NOT to have a switch, fuse,
or breaker in that line. Perhaps a large wire cutter nearby would be
useful. Personally, my battery terminal clamps have wing nuts squeezing
them on the posts the idea being that I could get one off quickly if
needed.]
>
> Let the flames begin! ;)
>
> Jim.
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