How To Tell If Your Alternator Is Charging. How to Check if Your Alternator is Charging Your Battery. To test the charging system connect the black meter lead to the negative battery terminal and the red meter lead to the positive battery terminal.
Then start the engine and check for increased voltage readings. If you got 142 or more volts the alternator is charging fine. Or that your gauges are behaving strangely.
If you cant get it to restart this is a sign the alternator is doing its job of keeping the battery working while the motor is running but the battery isnt.
Often youll see the red battery icon light stay on but you may also see a Check Engine or ALT indicator. Usually the first sign that your charging system is in trouble is a battery ALT or CHARGE warning light illuminating on your instrument panel while driving. Another simple test is to turn on your boat lights and see if they get brighter after you start the motor a voltage increase. Start the engine and set the voltmeter on DC voltage.
