If that charger isn’t doing the job, get a new charger.
Calibrate your multi meter?? Lol 1978 called and wants their antique multimeter back…
This is another non issue. Go get a decent charger/maintainer and toss the old one in the round file.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold