Weird trouble code spn 168 fmi 13

[Carhauler]

2015 Pete 389 cm2350. All started over a year ago when someone else drove my truck while I was on vacation and killed the batteries multiple times. (No idea how). Code is active, have cleaned all the cables and grounds I can find, checked relays and fuses. Insite ecm voltage while running is 13.5 to 13.75 all the time. Dash gauge is 13.75-14.0. Batteries read 14.2.
Also changed alternator. I checked insite and it doesn’t even acknowledge the code. The description is battery potential input 1 out of calibration.
Hope someone has a idea. Cause this truck has had weird issues with running sensors and such.
Thanks.