250 XS Problem

[bep078]

I have a 2010 Mercury 250 XS with around 80 hrs. After a full day of intense driving in rough offshore conditions, I observed the Voltage going down the more time passes by, until in went under 11.4V which activates the Smartcraft Check Engine warning. In the beginning, The alarm was sounding at 3500 rpm, then i left it in idle and warning went off. However, voltage was still low at 11.6V. Some time passed until i drove slowly to put the boat up and by the end, the alarm was sounding all the time and voltage went down to 11.2V.

What do you think this could be? Alternator gone? Something to do with the Voltage regulator? Batt dead?

Any feedback will be greatly appreciated.

Kind regards.

[Ace]

Check and clean,tighten every connection related to the charging system,battery cables, harnesses,relays,power trim connections,check alt for correct voltage output,check fuse link to alt. Check connections for hot spots.
The engine will code at 11.2 for low voltage,install a high quality battery also if needed. Check any accessories linking to the battery that the motor is using.

[espen]

Hi ! I just had both alternators quit charging , the engine performance fells off as voltage drops . I opened up both alternators because they are over priced in my aria , I did see some new for less than 100usd at ebay. As I see it there is one big problem with the altenator , the diode plate is of aluminium and the + connector is in copper , it will corrode easily in between and a thin layer of oxydes here stops any charging easily. To top of the problem the screw holding the alu plate and copper part together is tiny kind of wood screw that does not create sufficient pressure to keep the water out , I was thinking maybe solder the surface of the copper to lessen the corrosion problem . I solved it by adding 2 separate lines directly from alu plate to + on the batterycable connection , at Ace says , the fuse cable is common problem , just make a new cable or a jumper over the fuse. Both alternators is charging again after this modifications.
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[bep078]

Turns out the alternator blew the rotor. Took it to the shop, $50 and a couple of days later it was fixed. Hope it holds... I belive that it was always problematic as i never remember the batt voltage 14v+ when the motor was on idle as is now. Thanks for all your help..