More battery data
One more thing about batteries....
When you test a battery with a voltmeter, they develop a "surface charge" that gives a false reading. You need to put on a load for a short time to drain this off to get an accurate reading. You might want to play around with a hydrometer AND your voltage meter to get a correlation of volts and actual percentage of charge. There is a great meter known as
an e-meter that will tell you amps used, charge level, etc. The bummer is that they cost almost $200. I have one, but sure could not justify it for the boat. There are also small AMP meters that work by holding them over the wire - or for your needs, a regular automotive amp meter would tell you the rate that you are charging and discharging the battery.
Good battery chargers vary the voltage and rate of charge, but I doubt that this is happening with your outboard's charging circuit.
When you test a battery with a voltmeter, they develop a "surface charge" that gives a false reading. You need to put on a load for a short time to drain this off to get an accurate reading. You might want to play around with a hydrometer AND your voltage meter to get a correlation of volts and actual percentage of charge. There is a great meter known as
an e-meter that will tell you amps used, charge level, etc. The bummer is that they cost almost $200. I have one, but sure could not justify it for the boat. There are also small AMP meters that work by holding them over the wire - or for your needs, a regular automotive amp meter would tell you the rate that you are charging and discharging the battery.
Good battery chargers vary the voltage and rate of charge, but I doubt that this is happening with your outboard's charging circuit.