Good morning. Maybe someone can help me with a perplexing problem before I
have to turn it over to an auto/boat electrician. The boat is a Buccaneer
470 with an 82 Evinrude 90hp V4. I use it trolling for Trout on Lake
Toupo - running the main engine about 30 minutes a day, and on the trolling
motor (no charging coil) for about five hours a day. The ignition is always
switched off when trolling, and the fish-finder draws 350mA. The battery is
new (2nd one I have purchased) and has 44 amp hour reserve capacity)
The symptom was a flat battery after three days connected to the main
terminals. I had an isolating switch installed and used it at night to
isloate the battery. No difference - flat battery again after four days.
So I put a multi-meter in series with main positive terminal and I found
that there is a 32mA current drain with everything turned off. With the
battery isolator switch on the off position, no current drain. The boat
shop checked the rectifier and charge current - reported as all OK. (?)
Then I began to disconnect all the electric service wires at the battery one
by one - fish finder, nav lights and ignition. No effect on current drain.
It was the main wire to the engine (presumably the ignition/charge wire)
that was drawing the current. Fishing around in the engine (I am no expert)
I could not find any spurious voltage. The main (large diameter) red to the
starter solenoid was live, as was one smaller red wire to a centre relay
connection - but that was it. I then checked all the metal fittings, engine
casing, boarding ladder, etc, in case there was a short somewhere - no
result.

So, sorry about the long-winded preamble, but what should I check next??

Thanks

Bob McMillan
New Zealand

"Bob McMillan" wrote
...there is a 32mA current drain with everything turned off.

Lets see, 32ma x 100 hours (four days) is 3200ma or 3.2 amps of drain.
That's only 7% of a fully charged 44ah battery. Maybe your use of
fishfinders, etc., drains the battery heavily. Evinrude 90hp V4
allegedly has a 60amp alternator on it, 15 minutes on the trip back =
only 15 amps back into the battery. And that's assuming your 44ah
battery can take a 60 amp charge, 1.4 times the battery capacity. A
regular lead acid can't take that abuse, gel cells or AGMs might.

And that's assuming the motor's running near full speed; if you're
going slow the alternator could be putting out zilch. The battery
slowly slips into a nearly discharged state where 4 days takes the
last few amps out and you can't start the engine.

Take the battery home and charge it fully (or run around the lake for
an hour or so), then try running the engine for a half hour on the run
back, to keep it charged, or revved up a bit at the dock for a half
hour (that'll make you popular). A bigger lead acid, or 44ah AGM/gel
cell battery might accept a higher charge rate and allow you to get
away with only 30 minutes charging per trip.

That mystery 32ma current is probably keeping a relay open in the
engine or some such thing. Some regulators leak a little current when
not in use. Could be anything, but I don't think it's your problem.

"Bob McMillan" wrote in message
...
Good morning. Maybe someone can help me with a perplexing problem before
I
have to turn it over to an auto/boat electrician. The boat is a Buccaneer
470 with an 82 Evinrude 90hp V4. I use it trolling for Trout on Lake
Toupo - running the main engine about 30 minutes a day, and on the
trolling
motor (no charging coil) for about five hours a day. The ignition is
always
switched off when trolling, and the fish-finder draws 350mA. The battery
is
new (2nd one I have purchased) and has 44 amp hour reserve capacity)
The symptom was a flat battery after three days connected to the main
terminals. I had an isolating switch installed and used it at night to
isloate the battery. No difference - flat battery again after four days.
So I put a multi-meter in series with main positive terminal and I found
that there is a 32mA current drain with everything turned off. With the
battery isolator switch on the off position, no current drain. The boat
shop checked the rectifier and charge current - reported as all OK. (?)
Then I began to disconnect all the electric service wires at the battery
one
by one - fish finder, nav lights and ignition. No effect on current
drain.
It was the main wire to the engine (presumably the ignition/charge wire)
that was drawing the current. Fishing around in the engine (I am no
expert)
I could not find any spurious voltage. The main (large diameter) red to
the
starter solenoid was live, as was one smaller red wire to a centre relay
connection - but that was it. I then checked all the metal fittings,
engine
casing, boarding ladder, etc, in case there was a short somewhere - no
result.

So, sorry about the long-winded preamble, but what should I check next??

Thanks

Bob McMillan
New Zealand

If, when the isolator switch is operative, the ammeter shows a nil current
drain, and the alernator is charging as specified, then the battery must be
faulty. If you are taking out more current in normal use than you are
putting back in, then either the charging circuit is faulty or your usage is
to blame.

--
Remove "nospam" from return address.

"Bob McMillan" wrote in message ...
Good morning. Maybe someone can help me with a perplexing problem before I
have to turn it over to an auto/boat electrician. The boat is a Buccaneer
470 with an 82 Evinrude 90hp V4. I use it trolling for Trout on Lake
Toupo - running the main engine about 30 minutes a day, and on the trolling
motor (no charging coil) for about five hours a day. The ignition is always
switched off when trolling, and the fish-finder draws 350mA. The battery is
new (2nd one I have purchased) and has 44 amp hour reserve capacity)
The symptom was a flat battery after three days connected to the main
terminals. I had an isolating switch installed and used it at night to
isloate the battery. No difference - flat battery again after four days.
So I put a multi-meter in series with main positive terminal and I found
that there is a 32mA current drain with everything turned off. With the
battery isolator switch on the off position, no current drain. The boat
shop checked the rectifier and charge current - reported as all OK. (?)
Then I began to disconnect all the electric service wires at the battery one
by one - fish finder, nav lights and ignition. No effect on current drain.
It was the main wire to the engine (presumably the ignition/charge wire)
that was drawing the current. Fishing around in the engine (I am no expert)
I could not find any spurious voltage. The main (large diameter) red to the
starter solenoid was live, as was one smaller red wire to a centre relay
connection - but that was it. I then checked all the metal fittings, engine
casing, boarding ladder, etc, in case there was a short somewhere - no
result.

So, sorry about the long-winded preamble, but what should I check next??

Thanks

Bob McMillan
New Zealand

Bob,

I had the same kind of thing years ago, drove me crazy. It turned out
to be the alternator, replaced it, problem went away.