Hi everyone,

I'm new on this group, but have seeked advise before by searching
through past topics.

I have a Challenger 40 sloop, and have a question on testing my
alternator and voltage regulator. I replaced both several months ago,
and now I'm not getting any output from my alternator. I have a
perkins 4107 diesel. When I hook up a voltage tester to the
alternator, with the engine running, I read the same voltage as the
battery, around 12.5. volts. When I hook up the tester to the
regulater, I do not read anything. Does this mean I have a bad voltage
regulator? Does anyone have a method of isolating if the issue is with
the regulator or the alternator?

I would appreciate any thoughts/ideas. This is a great group btw, with
a lot of experience and knowledge.

Peter:

Here's a link to a very useful guide by Fluke.


http://assets.fluke.com/appnotes/aut...e/beatbook.pdf
beatbook.pdf (application/pdf Object)

Good luck!

Chuck

Peter

I have upgraded several of these installations on boats and have found that
the best way is to find a more modern car alternator that is self contained
that has the same mounting fittings and throw all the seperate relays and
control boxes away

The end result would be a better charging system with easier to get
replacement parts should that alternator fail. And also there are not many
people around who understand the older charging systems apart from the parts
being expensive and difficult to get.

The wiring on a new alternator is very easy, one heavy duty wire to the
battery and one small to a red indicator light on your dashboard and the
other wire from the red light to your ignition switch

Tony uk


"chuck" wrote in message
ink.net...
Peter:

Here's a link to a very useful guide by Fluke.


http://assets.fluke.com/appnotes/aut...e/beatbook.pdf
beatbook.pdf (application/pdf Object)

Good luck!

Chuck

"Peter253" wrote in
oups.com:

When I hook up the tester to the
regulater, I do not read anything. Does this mean I have a bad voltage
regulator? Does anyone have a method of isolating if the issue is with
the regulator or the alternator?

You don't read anything from lead to lead or lead to ground or where? What
kind of regulator is it? Do you know which of the leads on the regulator
is battery, field, ground, etc.?

If there is no voltages to the regulator, you have a wiring problem. The
new regulator won't have operating voltages, either.

--
Larry

"Tony" wrote in
:

I have upgraded several of these installations on boats and have found
that the best way is to find a more modern car alternator that is self
contained that has the same mounting fittings and throw all the
seperate relays and control boxes away



I agree a modern, self-contained car alternator is a much better
alternative than this money ripoff boat nonsense with the $300 regulators.
Batteries are just too simple...float 'em and they work great.

But, alas, a car alternator doesn't have to worry about fumes in the bilge
so it's not explosion proof. Marine alternators are supposed to
be...right? I hope so. Even on a diesel powered boat like this there is
the possibility of propane gas, gasoline fumes from the dingy engine and
gas storage, etc., so it might be safe to use a car alternator in the boat.

Sure would be much cheaper, though...(c;

--
Larry

Umm yes Larry I agree, but ill bet he is using an old car type alternator
neway and yes its probably not explosion proof but I dont suppose the
starter is either or the starter solenoid.
Just put your bilge ventilation fan on a coupla minutes before you use your
engine

Tony uk

"Larry" wrote in message
...
"Tony" wrote in
:

I have upgraded several of these installations on boats and have found
that the best way is to find a more modern car alternator that is self
contained that has the same mounting fittings and throw all the
seperate relays and control boxes away



I agree a modern, self-contained car alternator is a much better
alternative than this money ripoff boat nonsense with the $300 regulators.
Batteries are just too simple...float 'em and they work great.

But, alas, a car alternator doesn't have to worry about fumes in the bilge
so it's not explosion proof. Marine alternators are supposed to
be...right? I hope so. Even on a diesel powered boat like this there is
the possibility of propane gas, gasoline fumes from the dingy engine and
gas storage, etc., so it might be safe to use a car alternator in the
boat.

Sure would be much cheaper, though...(c;

--
Larry

Thanks for the tips everyone. I suspect a wiring issue as (I believe),
I should have voltage on the regulator. I have two battery banks, one
that has 2 6volt golf cart batteries for the house, and one separate
marine starter battery that is just to start the engine, nothing else.
I intentionally ran down the house battery to test the alternator.
When I ran the engine and tested the voltage on the alternator, it read
12.42 volts, which was the same as the house battery before I started
the engine. When I switched the control to charge the starter battery,
I read 12.75 volts (the same as the starter battery before running the
engine). So, the alternator reads what the voltage is on the
batteries, but is not charging them.

I'll follow the steps to bypass the regulator to see if the alternator
is functioning. I hope it's wiring issue, that would be a lot less
expensive to fix! If the alternator is out, I fear I've got a bigger
issue because I had it professionally rebuilt about 6 months ago.
So..that would mean something caused it to burn out.

Thanks again for the tips. I'll keep you all posted.

Peter

"Peter253" wrote in
ups.com:

So, the alternator reads what the voltage is on the
batteries, but is not charging them.



How long did you charge the down house batteries and track the voltage? If
the batteries are down a good bit, do not expect to see 14V across the
charging battery terminals. That comes later after the charging current
drops off below the rated output of the alternator. The voltage rises,
slowly, in a curve as the alternator strains to provide the current it was
designed for. You get hardly any voltage rise on a battery that's way down
until the alternator's regulator starts to feel the need to drop the field
current. The other factor, one that is hard to detect in boats, is "belt
tightness and loading". Someone asked me to look at their alternator and
regulator down the dock not long ago. He had his wallet out ready to BOAT
(bring out another thousand) to replace it all, which I suppose makes his
boatyard quite happy to fulfill. At the dock, after the AC charger had
pulled the gravity up to 1.240+, I cranked the engine and she came right up
to over 14V on my DVM on the house batteries. However, as I went through
the cabin turning every load on I could find, the voltage went all to hell
trying to provide 30-40A to my loads. Nothing squealed, like your dry-
bilge car will do. Still loaded, I crawled down to watch the alternator
run and notice it had climbed up its belt from the pull on it. I had him
shut down the engine and found the pulley on the alternator hot to
touch....the belt was slipping. Now shut down, the belt was quite tight,
once again. Cranking it under load and the alternator climbed the belt,
pulling the engine sideways because this alternator had been added for the
house battery alternator mounted to the frame, not the block. The forward
engine mounts were bad. Once replaced, I didn't have enough DC load in the
boat with everything on to make the alternator voltage drop off below 14V,
power to spare. Steak and a fine English ale are such good companions
after a day in the bilge...(c;

Watch the belt as you load the system down and make sure it stays tight. I
didn't use mine on this impromptu project, but I have an old Strobotac
flashing light strobotac I could have used to detect the slippage as the
alternator slowed. You can also hear the alternator really loading down
the little diesels in sailboats. If there's only 17hp, total, and you
don't have it in gear, the RPM drops significantly as you load down the
alternator on a charged-up battery bank.

With this new information about discharged house batteries, I'm leaning
towards poor power transfer...slipping belt. Is this alternator mounted to
the engine block or the mounting, which is notorious for slippage?

--
Larry

Peter253 wrote:

Thanks for the tips everyone. I suspect a wiring issue as (I believe),
I should have voltage on the regulator. I have two battery banks, one
that has 2 6volt golf cart batteries for the house, and one separate
marine starter battery that is just to start the engine, nothing else.
I intentionally ran down the house battery to test the alternator.
When I ran the engine and tested the voltage on the alternator, it read
12.42 volts, which was the same as the house battery before I started
the engine. When I switched the control to charge the starter battery,
I read 12.75 volts (the same as the starter battery before running the
engine). So, the alternator reads what the voltage is on the
batteries, but is not charging them.

I'll follow the steps to bypass the regulator to see if the alternator
is functioning. I hope it's wiring issue, that would be a lot less
expensive to fix! If the alternator is out, I fear I've got a bigger
issue because I had it professionally rebuilt about 6 months ago.
So..that would mean something caused it to burn out.

Thanks again for the tips. I'll keep you all posted.

Peter


It sounds likely that you have lost excitation to your alternator.
It normally needs only a few milliamps of current in the rotor to
excite the stator coil. If you can find the field wire and make
certain it has 12 volts connected to it, it may all spring back to
life. You could inspect the brushes to ensure they are feeding the
rotor.

These are small things to fix, and doing them yourself could save
the all up full service complete teardown and replacement of stuff
you don't need.

An alternator rebuild kit is only a few dollars and is a snap to
replace, especially if you don't need to do the bearings or main
rectifiers. It replaces the regulator and brushes all at once. It is
possible you have a single loose connection inside, which you might
snug up yourself.

If you are going to take the thing to an alternator shop, you are
only two bolts away from dissassembling it yourself along the way,
anyway.

What could cause premature failure? A bad repair? An excessive
load? A loose belt or pully slipping? opening the ouptut line while
running at hard charge? Do you have a battery switch? does it have a
field interuptor set of contacts? Those field interruptor switches
are notorious points of failure. When they fail open, your
alternator just quits, becase it gets no excitation. It happened to
me.

I would make sure you have juice at the field terminal, first.

Terry K

I agree a modern, self-contained car alternator is a much better
alternative than this money ripoff boat nonsense with the $300
regulators. Batteries are just too simple...float 'em and they work
great. .

This got my attention.

An older sailboat ('79) I just purchased, has two West Marine SeaVolt
gel batteries and what appears to be the stock alternator that came with
the Perkins 4-108. I see no external regulator.

Should I replace this old alternator? If so, can I use an automobile
regulator? I was pricing exactly what you panned - marine alternators
like Balmar with external regulators and echo chargers linking house to
starting battery.

It certainly would be far cheaper if I could use a car alternator.

TIA for any info.