1980-81 Mercury 115 Tower i-6 convert stock rectifier to regulated CDI?

[OldVintageOutboardMan]

I ran the diagnostic ladder test on my '80-81 Mercury 115 Tower of Power and the rectifier failed the test. I understand the stock rectifier has no capacity to regulate the voltage and leads to shortened battery life due to frequent overcharging. The standard rectifier is the 3 post with 4 wires, the voltage regulated CDI unit has 3 wires and the ground. Has anyone upgraded their rectifier to the improved CDI unit? Anyone experienced with this conversion? Thank you.

 

[jimmbo]

Those unregulated system don't put out a great amount of current, in most cases they never get the batteries fully charged. The main thing regarding battery life is to only use Wet Cell batteries that water can be added to. AGM and sealed Maint-Free Batteries are a no-no

 

[OldVintageOutboardMan]

Thanks jimmbo. I double checked with my reading glasses this time and I didn't have the diagram oriented correctly. The rectifier passed the ladder test. Would a volt meter or an amp meter be a wise investment? There's a Wet Cell battery on my list of supplies now. Thanks

 

[merc850]

A volt meter is a good addition to your instrument panel; the ammeter would have to be wired between the rec. output and the wiring harness which could be a source of trouble if a wire shorted or came loose.