You have a second meter to test it?
Make sure it's really at 16v?
Test the voltage regulator.
Using a digital Volt/Ohm meter, Check the resistance of the rectifier as follows: _______Red Meter Lead Black Meter Lead Reading ENG GND AC 1 over I M Ohms ENG GND AC 2 over I M Ohms AC 1 + BAT over I M Ohms AC 2 + BAT over I M Ohms AC 1 ENG GND Open AC 2 ENG GND Open + BAT AC 1 Open + BAT AC 2 Open
* Diode readings are to be read one way, then reverse the leads and read again. You should get a low reading in one direction and a higher reading in the other.
Maximum Output Test 1. Install an ammeter capable of reading at least 15 amperes in-line on the red wire from the rectifier to the starter solenoid. 2. Connect a load bank to the battery. 3. In the water or on a Dynometer, start the engine and bring the RPM up to approximately 4500 in gear. 4. Turn on the load bank switches to increase the battery load to equal stator capacity and check the ammeter. 5. If the amperage is low, A) Check the load bank connections and meter for battery draw. B) If the output is still low, check and clean all connections between the battery and the rectifier. Inspect stator windings for burned or discolored windings. 6. If the amperage is correct, but the battery voltage remains low, replace the battery.
Overcharging 1. Using a voltmeter, check the voltage on the battery and compare it to the voltage on the red wire connected to the starter solenoid to engine ground. 2. If the voltage is high on the engine compared to the voltage on the battery, do a voltage drop test and try to isolate the area where the problem is. 3. If the voltage is the same on the battery and the engine, but is over 15.5 volts at 4500 RPM, replace the battery with a known good high quality MARINE battery. 4. A continued high voltage reading may indicate the need for a regulator/rectifier combination instead of an rectifier only.
