99 four stroke not charging

[brand-x]

Hello I am asking this for my dads boat it's a 99 four stroke we had the battery go dead then when I got home we checked it out and it is not charging then I noticed the rectifier smoking from the back he had to replace it one year ago because the motot would not run this time it still runs just not charging any idea what could cause this ? also the replacment part was used thanks George

[boats.net]

It's probably a bad regulator. Check all elect., ground and battery cable connection's, make sure connections are clean and tight.