Beware some older Mercuries have unregulated charging systems.
I've seen 17v on some, the only easy fix is to always run with the lights
and radio on.

-W


--
CC Marine

Lake Hartwell SC
"Where the fish are always biting, and the swimmers are always nervous!"


"Tim" wrote in message
ups.com...
On Jul 18, 11:58 am, "Midlant" wrote:
Took a reading while running about 3k. 13.8volts

This is on a 1987 135hp Mercury. I had posted this question little over
a week ago. Thought I'd give an update.

John

I'd say that's right on the money.

The old "rule of thumb" concerning 12v charging systems was anywhere
between 13.8 and 14.2