300xs low voltage fault

[Bcv33oceanhawk]

twin 2007 300xs with around 235 hours have both had a low voltage fault recently and went into guardin mode. After reducing throttle to idle they come out of guardian and everything seems fine. Batteries read 12.6 with engines off and 14.2 with engines at idle. Batteries are interstate group 24 800cca 1000mca. Any suggestions on what is causing this.

[XstreamVking]

Loose/bad connections. Could be battery switch connections, or switch's internal sweep mechanism. Prob not motor related. Easy stuff first, start at the batts, load test them, and work up to the motors inspecting all connections. Batts isolated 1 to each motor might help diagnose. How old are the batts?

[Bcv33oceanhawk]

Batteries are around 6 months old. I'll take a look at all the connections and see if I can find anything. Thanks

[vnemous]

I dont know if this is your problem but Mercury recommends a 1000 cca battery minimum for opti motors.

[Wayne Cammidge]

You could also have a problem on the boat sensor harness.
Check that you are getting 5vdc on both the sensor circuits

[obrien]

The batteries he has are the correct ones. Mercury recommends 800 cca/1000 mca

be sure to check the clean power fuses at the batteries. If there is a little bit of corrosion it can cause this problem. I just recently had this same issue on a boat at work. Found that one of the clean power fuses had a crack in it and had some corrosion inside the housing