check charging

[beckoning]

My 1989 100hp inline 4 Mercury may or may not be charging the batteries. How can I tell? I use an external charger to assure the batteries are topped off, but I've recently experienced signs of low battery power. The batteries checked out fine. I would like to do a quick-n-dirty check to see if the alternator is putting out. I have a volt meter. The boat sits in a hoist so the motor is somewhat difficult to get access. Any easy methods to check if the alternator is putting out? Any ideas?

 

[Barnacle_Bill]

Check the voltage at the battery with the motor running. At about 2000 RPM you should be reading 13-15 volts DC.

 

[ihearth2o]

easiest way I know is to check your alternator gauge before and after you start your motor. Should be higher after you start. You could also try turning on lights or blower to see if the voltage readings drop.

 

[beckoning]

Check the voltage at the battery with the motor running. At about 2000 RPM you should be reading 13-15 volts DC.

Thanks. That's helpful. I have an outboard, so there is no alternator gauge. Checking voltage at the battery when "idling" at 2000 rpm is an easy thing to do.