12v electrical issues

[mrgscooter]

Have not ever noticed this. Looking at Firefly display, 13.2v house and when I turn on lights, it drops to 12.8v, 12.7v and I turn off lights. Then display goes back to 13.2v , the coach is connected to 20amp shoreline to house. I checked the house batteries, and the fluid levels are good. Is this normal or a sign the original batteries (3yrs) are close to toast. Any suggestions are appreciated.

[Pete'sMH]

Entirely normal. A fully charged battery will be 12.8V. The higher voltage with no load is actually the charging current. No worries.