Jeremy Mitchum

I have a 2015 Silverado 2500 6.0 and it has started loosing charge overnight. I have put two different new batteries in it but it’s definitely a parasitic drain that happens after the trucks been sitting more than around 10 hours. The truck seems like it overcharges the battery sometimes while driving and has actually thrown high voltage codes a couple times. The alternator has tested good. Is there a charge controller is anything that goes bad these? I thought I read somewhere that these trucks had issues with the RAP or ECU draining batteries after it had been off for a while. Has anyone else encountered something like this?