1999 Johnson 150 carb outboard. Put in a new battery last summer.
Voltmeter normally shows 14-16 volts and has since new. Couple weeks ago I
went for a short run (it stays in the water year-round), and I noticed the
voltmeter was showing nearly 18 volts. Turned on the running and dock
lights, but it stayed there at about 3k rpm. Not until I got back to the
no-wake did it drop back to 14 or so. It cranked up just fine, no dragging
like the battery is going bad again.

I've read all about the terrible charging circuits outboards have in them.
There doesn't seem to be much of a regulator in there, but 18 volts is way
too much, and a change from what I'm used to seeing. Any ideas? Is this a
known fault that outboards, or Johnsons develop?

Thanks...

Jack

Yes, it is called a voltage regulator. They go bad from time to time. Tend
to be more of a problem on OMC than Merc or Yamaha. You need to replace it
before you burn up another battery.

--
Tony
My boats and autos - http://t.thomas.home.mchsi.com



"Jack Goff" wrote in message
m...
1999 Johnson 150 carb outboard. Put in a new battery last summer.
Voltmeter normally shows 14-16 volts and has since new. Couple weeks ago
I
went for a short run (it stays in the water year-round), and I noticed the
voltmeter was showing nearly 18 volts. Turned on the running and dock
lights, but it stayed there at about 3k rpm. Not until I got back to the
no-wake did it drop back to 14 or so. It cranked up just fine, no
dragging
like the battery is going bad again.

I've read all about the terrible charging circuits outboards have in them.
There doesn't seem to be much of a regulator in there, but 18 volts is way
too much, and a change from what I'm used to seeing. Any ideas? Is this
a
known fault that outboards, or Johnsons develop?

Thanks...

Jack

"Jack Goff" wrote in message
m...
1999 Johnson 150 carb outboard. Put in a new battery last summer.
Voltmeter normally shows 14-16 volts and has since new. Couple weeks ago
I
went for a short run (it stays in the water year-round), and I noticed the
voltmeter was showing nearly 18 volts.






The '99 V6 small-block has a pretty reliable voltage regulator design. It
is pretty rare that they fail, but usually it is from corroded connections,
wing-nuts on the battery, or hooking up the cablese or a battery charger
backwards. Be sure the connections are clean and that there are lockwashers
and stainless hex nuts on the terminals.

Check your voltmeter accuracy first. With the key ON and motor not running,
make sure it reads about 12 volts and not 14 or 16 meaning the meter is out
of calibration. Also you can put an accurate digital meter directly on the
battery terminals and run the motor, comparing both the dash meter and the
digital meter readings.

If the regulator is indeed faulty, it is around $200 and easily installed.

Bill Grannis
service manager

"Billgran" wrote:
"Jack Goff" wrote in message
Couple weeks ago I
went for a short run (it stays in the water year-round), and I noticed
the
voltmeter was showing nearly 18 volts.


The '99 V6 small-block has a pretty reliable voltage regulator design. It
is pretty rare that they fail, but usually it is from corroded
connections,
wing-nuts on the battery, or hooking up the cablese or a battery charger
backwards. Be sure the connections are clean and that there are
lockwashers
and stainless hex nuts on the terminals.

Check your voltmeter accuracy first. With the key ON and motor not
running,
make sure it reads about 12 volts and not 14 or 16 meaning the meter is
out
of calibration. Also you can put an accurate digital meter directly on the
battery terminals and run the motor, comparing both the dash meter and the
digital meter readings.

If the regulator is indeed faulty, it is around $200 and easily installed.

Bill Grannis
service manager

Thanks, Bill. It does read 12v before starting. I had already planned to
take the DVM with me when I go today to get a sanity check on the onboard
voltmeter. The battery cables were replaced last year as well (muskrat
chewed the old ones), so the connections should be solid, but I'll look at
that too.

From your and Tony's post, it sounds like the voltage regulator. I'm sure
it'll be the most expensive thing... grin

Jack

Well... I went out this afternoon and this is what I found.

A DVM on the battery posts measures about 13.8v when it's running. Took the
motor cover off and measured at the battery cable terminals inside and it
measures the same.

All the while the boat voltmeter reads pretty much pegged full scale... 18v.
The voltmeter has obviously gone south. That should be a lot cheaper than a
voltage regulator. :-)

Jack

"Jack Goff" wrote in message
m...
Well... I went out this afternoon and this is what I found.

A DVM on the battery posts measures about 13.8v when it's running. Took
the
motor cover off and measured at the battery cable terminals inside and it
measures the same.

All the while the boat voltmeter reads pretty much pegged full scale...
18v.
The voltmeter has obviously gone south.



Glad to hear that it's a relatively inexpensive repair. It pays to test the
simple stuff first. The stator on your motor plus the labor, is the most
expensive part of the charging system, and the ignition system.

Bill Grannis
service manager

Just as another sanity check, look at the voltage at the voltmeter when it says
18v. You may still have a bad connection between the alternator and the
battery.

"Jack Goff" wrote in message
m...
Well... I went out this afternoon and this is what I found.

A DVM on the battery posts measures about 13.8v when it's running.

Okay, the battery is not being damaged.


All the while the boat voltmeter reads pretty much pegged full scale...
18v.
The voltmeter has obviously gone south. That should be a lot cheaper than
a
voltage regulator. :-)


Use the DVM to measure the same point that the voltmeter is seeing.

Even if they don't agree, it is possible that the voltmeter is not "bad", it
just might be making different assumptions.

When you take a measurement of a "DC" signal, you basically have to assume
that the voltage is constant. If the voltage is not constant, how the meter
deals with it can give you wildly different readings.

Usually, an "analog" voltmeter will give you a nice average of the signal,
as the mass of the meter movement dampens things out. It is possible that
even an analog movement has some non-linear components in it that might be
causing it to detect peaks.

Cheap digital meters can give very erratic readings as they get sampling
errors. Better digital meters will filter out the higher frequency noise so
that it can get reasonable measurements.

It is possible that the voltage output from your outboard has become very
"spikey", and that the in dash voltmeter is responding to the spikes instead
of the average.

Rod

Rod,
A Fluke 87 DVM will also give you peak and low readings.
Paul

"Rod McInnis" wrote in message
...

"Jack Goff" wrote in message
m...
Well... I went out this afternoon and this is what I found.

A DVM on the battery posts measures about 13.8v when it's running.

Okay, the battery is not being damaged.


All the while the boat voltmeter reads pretty much pegged full scale...
18v.
The voltmeter has obviously gone south. That should be a lot cheaper
than
a
voltage regulator. :-)


Use the DVM to measure the same point that the voltmeter is seeing.

Even if they don't agree, it is possible that the voltmeter is not "bad",
it
just might be making different assumptions.

When you take a measurement of a "DC" signal, you basically have to assume
that the voltage is constant. If the voltage is not constant, how the
meter
deals with it can give you wildly different readings.

Usually, an "analog" voltmeter will give you a nice average of the signal,
as the mass of the meter movement dampens things out. It is possible that
even an analog movement has some non-linear components in it that might be
causing it to detect peaks.

Cheap digital meters can give very erratic readings as they get sampling
errors. Better digital meters will filter out the higher frequency noise
so
that it can get reasonable measurements.

It is possible that the voltage output from your outboard has become very
"spikey", and that the in dash voltmeter is responding to the spikes
instead
of the average.

Rod