This problem comes up over and over again in the newsgroups and boating boards
and NO ONE has answered it...

A lot of older outboards came with un-regulated charging systems and I have
one.
I read about people reporting that their voltage had risen to 16+ volts. Last
year after over TEN years of correct voltage I bought a new battery and mine
started doing the same thing. I verified this with the boats volt meter gauge,
a Fluke digital VOM and a Simpson 260 analog VOM. There is 16 volts there.
Everything in the charging system is within specs. I have even replaced a lot
of the system and its still 16+ volts. After not getting an answer from anyone
(including the manufacturer) as to what can cause this I just let it go to see
what would happen. Its been running 2 seasons like this so far and nothing bad
or what should be expected has happened.

1. Nothing has burned out or been hurt. (Fish finder, lights, guages, GPS)
2. It has not caused the battery to boil off water, I have not added one drop.
The battery is FINE.

Some people have reported that turning on accesories will drop the voltage and
this is correct. It worked on mine for a while but it will eventually charge
the battery and runs around 15 volts. Leaving the lights on for a while to
discharge the battery will do the same thing. Its amazing how this 5 amp
system can charge so fast.

After many trys I finally got to actually speak with an engineer at the
manufacturer. He told me they were always aware of this high voltage and their
guages (OMC) were specifically designed to handle the higher voltages without
harm. I asked him why they would even make a system that could even produce 16
volts in the first place and he said "it could do 45 volts". WHAT!!!!!!

I asked why they were not concerned about the battery gassing and causing an
explosion. His reply was that their un-regulated charging systems produce a
very low amperage. Mine is around 5 amps. He said in a simple un-regulated
charging system there is a stator (generates AC) and a rectifier (changes AC to
DC) and the battery acts as the regulator. He could not tell me why mine has
run all these years at 13.5 - 14.5 volts and suddenly started running at 16.

He did give me these tips for ANYONE with an un-regulated charging system:

1. NEVER use a maintenance free battery.
2. NEVER use any of the new AGM batteries.
3. NEVER use one of the new spiral wound batteries.
3. ONLY use a battery with caps so you can check the water level on a regular
basis.

FINE.
I saw this motor run at the correct voltage for years and I refuse to just let
it keep doing this because it can. Being somewhat of an electrician I need a
reason.
I checked every wire and ground in the boat, they were fine. A loose ground
could cause a rise in voltage. I tested every plug and ground on the motor. I
disconnected everything from the boat except for the motor to eliminate wiring
problems and it STILL runs at 16 volts. I threw some money at it and bought a
new rectifier which didnt help.

Now I am down to the battery. The factory manual calls for a battery with "a
minimum of 360 CCA". I bought a battery with 1000 CCA and it went to 16 volts
instantly. I borrowed a battery with 600 CCA and got 16 volts after it charged
up. I bought another small battery with 420 CCA and have not had the chance to
test it yet. If this does not work I am going to try a battery combiner and
let it charge my deep cycle trolling battery too. If I give it a load, its
fine (about 14 volts). I could rig some kind of regulator to it but it never
had one before and shouldnt need it now.
On an interesting note a weak battery will let it run within normal voltage
range because it will never charge up fully. Problem with that is you cant buy
a weak battery.
I will test the new small battery (420 CCA) to see if that works, it stayed
under 14.5 volts on the muffs at around 1000 rpm's for about 10 minutes which
is a record. Since the smaller battery will discharge more during starting
it might give the charging system something to do but being smaller it might
charge up faster.... hmm.

If anyone out there has any logical suggestions I will try them and I would
like to hear from you. There has to be an answer to this. Could something
cause three VOM's to read incorrectly?

Also Sprach CCred68046 :

A simple answer to a long problem: Buy a solid state rectifier/regulator
intended for an old motorcycle. I bought one made by Tympanium and sold
as a replacement for Triumph motorcycles. Just be careful with polarity,
the old Triumph's had a positive ground electrical system. Make sure that
you connect the negative output to ground, even though the instuctions say
positive.

I bought mine locally, there's a great bike shop near me, but here's an
online retailer: http://www.oldbritts.com/17_01233.html

Dan

--
Give a hungry man a fish and you have fed him for a day, but give him a case
of dynamite and soon the entire village will be showered with mud and water
and hard-to-identify little chunks of fish.

A simple answer to a long problem: Buy a solid state rectifier/regulator
intended for an old motorcycle.

Thanks Dan,
As I stated in the first thread I know I could do that. I know I could get a
regulator kit from OMC or West Marine to do this too.
BUT....
I really want to know how this thing is defying physics and everything I was
ever taught about electricity.
It should be ruining stuff like the battery and electronics and its not. I can
afford the regulator easy but I want to know...
Why did it work perfectly for so many years and just change? If this were not
such a simple system I would buy the regulator and forget it.
I cant find ONE article doing a google search where someone has found out why
or how these old outboards are doing this.
16 volts should be frying stuff, even at 5 amps.
By the way, just curious again... what motor did you put that regulator on?
If anyone else has an outboard doing this I would like to know the brand and
horsepower.

Thanks!!

I had the same experience with my 1989 vintage merc/mariner 75. It started with
a new battery. All I could think was that they changed the way they make
batteries. I did notice lights didn't last as long after that and batteries
seemed to "boil off" a little faster but everything else was OK.

On 09 Jun 2004 14:05:58 GMT, obull (CCred68046)
wrote:

Why did it work perfectly for so many years and just change?

=====================================

The new battery is probably better at accumulating a surface charge
for some reason. It reaches full charge and keeps on going until it
reaches an equilibrium with the 5 amps or so that the alternator is
supplying. The older battery may have had a lower internal
resistance, different type of plates, more leakage, more capacity,
etc. Battery life will definitely be shortened under this scenario
and you may experience premature failure of voltage sensitive
equipment.

I had the same experience with my 1989 vintage merc/mariner 75. It started
with a new battery.
All I could think was that they changed the way they make
batteries.

That is exactly how mine did it. New battery and all the trouble started.
Every time I put the old battery back in it was fine but finally it just died
from old age. It lasted 4 years.

I had that same thought as you but from what I can see, refillable flooded cell
batteries are no different. Outside of adding some LED lighting, nothing on my
boat changed but the battery. I thought the LED's could have been suspect but
I took everything out of the system but the motor and it didnt change.
It almost has to be something with the battery. Right now I'm trying to find
out from an expert if a bigger CCA battery or a smaller CCA battery could make
a difference since it is the regulator in the system.

Thanks for the info.

Battery life will definitely be shortened under this scenario
and you may experience premature failure of voltage sensitive
equipment.

Exactly my point.
Based on everything I was taught, you should be right and that is exactly whats
NOT happening. NONE of those things have happened in two (almost 3) years now.
I intentionally let it go hoping something would burn up or die thinking I
could then solve this. I have not had anything burn out nor have I added any
water to the battery!

On 09 Jun 2004 15:29:40 GMT, obull (CCred68046)
wrote:

I have not had anything burn out nor have I added any
water to the battery!

=========================

Part of that could be luck with the electronics. The water not
boiling off can be explained by the low charging current and the
battery's apparent ability to develop a high surface charge.
Different battery, different results.

Part of that could be luck with the electronics. The water not
boiling off can be explained by the low charging current and the
battery's apparent ability to develop a high surface charge.
Different battery, different results.


Ok Wayne,
That makes sense but I have tried 4 different batteries so far. You would
think that I would have at least burn out a light bulb or something...
Based on your thoughts would you think that in a system like this a bigger
battery or a smaller battery should work better? Remember, as many others
mentioned, these things ran perfect for years as did mine then just went crazy.
Some of the old posts I found state the problem starts with a new battery.
Do you know of any major differences in regular (not maintenence free)
batteries of the 80's and what they have now?

On 09 Jun 2004 17:06:30 GMT, obull (CCred68046)
wrote:
Do you know of any major differences in regular (not maintenence free)
batteries of the 80's and what they have now?

======================================

I'm not aware of specific differences but there are differences
between manufacturers and between battery types, i.e., starting
batteries vs. deep cycle. I'm guessing a little but my sense of it is
that a smaller battery would be more likely to achieve a 100% charge
and float up to the kind of voltage you're seeing. It might be
interesting to connect a good size marine battery like a 4D in
parallel and see what hapens to the voltage. My guess is that it
would drop as the larger battery should be more capable of absorbing
charge.