Mercury alternator
 

Is there any easy way to check alternator output on Merc. 200 EFI? Is it just as easy as checking voltage on alternator while running? I have two Red Hot Mama cranking batteries just over a year old that are dead. Have a battery disconnect , so nothing is pulling them down while not in use. I was told these batteries do not do well when sitting for a while.

no battery will do good when sitting for a while they will go down in voltage which cause the acid and water to seperate...the acid will go to the bottom and eat the lead plates up ruining the battery.....this is why it is important to keep your batteries charged at all times.....you can buy a cheap maintainer for around 20-30 bucks lot cheaper than batteries


as far as the alternator i would say it would be the same as a car you should run around 14 volts while motor is running.