May be the wrong place but there are lots of 250 pro xs on here. What does your smart craft gauge show. I'm afraid my alt. Is not working right. Brand new battery and only showes 12.3 -12.8. When running

What is the voltage when you're running down lake? If it's not 13.5-14 there is an issue. I had something similar with my Yamaha but it was the rectifier, and a simple fix.

^^^^^^This, should be 13 - 14+ showing at 4,000 rpms and up

Mine runs the same. 12.6-12.8 on my smart craft gauges. Over on BBC there is a thread that the Mercury Gurus are talking about it. They said that they should only be reading 12.6

I thought at one time in the past it would get up around 14 volts but Saturday I had low voltage issues and when running and trimming the motor it would drop below 11 and then the alarms would go off and reduce power. Put a new battery on and it did fine but never saw it register over 12.8 while running even at 5000 rpms

You might check the fusable link from the alternator. Mine was doing that and i found the fuse blown. Since it was under warranty i bought the new part instead of just replacing the 100 amp fuse. I didn't want the boat sitting in the shop for two weeks when i could fix it for 58 dollars . RPM Leaders on ebay 58.00

You aren't going to be showing much more than 12.5-12.8 volts at idle....Like DEFMP said, normal voltage should be around 14v under any kind of load.

thanks Bruce, I might have to check on it. I bought my boat at lake fork and it's a 100 miles one way just to drop it off.

12.3-12.8 is while running down the lake at over 4000 rpm

That's weird! How well does a battery recharge with that little of a surplus? Even at 14 volts with the load our pumps, electronics, poles, ect put on the battery I am surprised we don't have more battery problems. Cranking plates, iirc, weren't made for constant cycles in charging.

I have a 2010 250 pro xs and I get 12.5-12.8 at idle and when I jump on plane and running down the lake my smartcraft gauge reads 13.8-14V