Electrical Charging Problem

This weekend I ended up in the middle of a lake with a dead battery in my '79 SN. This has happened to me three times in the past three years and has finally annoyed me enough to do something about it. The problem is it's so intermittent.

I'll be driving the boat quite awhile and then I'll go to start it and it will barely turn over and not start, shortly after that it won't turn over at all. After charging the battery everything will be fine for the next 2-4 months and then the same thing happens.

I've had the battery tested and it's good. The charging system must be working some of the time or I wouldn't be able to go 2-4 months between episodes. I'm thinking that either the alternator is charging intermittently or I've got a bad connection somewhere.

All of the wiring in the boat is original and the alternator and starter are both old (I don't know how old)

I'm going to start with replacing the battery cables since they're original and see where that gets me. Any other suggestions?

Additionally for those of you with similar boats what does your Ampmeter (Amps not volts) read when you're underway? Mine typically reads just to the positive side of zero.

mine will start out at about 20 amps then go back to almost zero after a couple minutes. I was chasing a simular problem three years ago and never could track it down. Replaced the battery cables with marine grade cables, replace the voltage regulator, replaced the battery and even cleand all of the connection and replaced the ignition switch and still had the problem until I replaced the Alternator with an internal regulated model and engine wiring harness from skidim. What type of battery are you running, a deep cycle or one that has less than 650 CCA won't work very well on this year of nautique. A deep cycle takes to long to recover and cannot produce the CCA needed if on a low charge. The ford starters like a lot of current and if the Cold Cranking Amp rating of the battery is low then it has trouble cranking the starter especially when hot.

You might find the batt cables are not the problem. Charging the batt and everything is ok means the connections are probably ok. It sounds like a possible alternator problem. Sounds like you lost a few diodes in the alternator and its only doing a few amps, but a little less than whats required causing a slow drain. A voltmeter at the battery with everything on better read 13 volts or more.

The voltage reading looks normal to me 13.5 volts is pretty much normal if it was down around 12.5-13.0 volts then I would be worried. have you tried changing the votage regultor? Also have you hooked a test light in series with the negitive cable to check if there is a battery drain?

How is your starter? When I first got mine, I could charge the battery all night...go to try to start it up for the first time, and it would usually start. If I tried it again, it would get harder and harder to start. It ended up being a bad starter and it was dragging the battery way down trying to start.

Also, I would check the belt to make sure it is tight. You should not be able to turn the pulley by hand easily (this was another of my problems).

Interesting. Anyone else agree with Tom? Why did the factory use ammeters in the first place?

Jeff is right on (IMHO). Simplified: Ammeters tell you the real time status of the charging system. Voltmeters tell you the status of the battery. With a voltmeter, you can have a charging problem and not know about the problem until the battery discharges enough to cause starting problems.