Todo del previoso es exactamundo correcto.
Sus batterias estan basura, problamente.
I agree, they're probably better left at the recycling center.
Mine are getting there (220 ah/r) but not quite that much drop yet, but they're over ten years old.
Eagle eyed readers may want to argue with my previous posts about battery age, as I've been GIVEN these latest batteries.
They're basically free and work 90% of new. Good enough for my sailing style.
As for yours, assuming they're lead acid, and not gel or AGM,give 'em a good equalizing charge.
Do an internet
or CF search for the particulars, I used a 19V. laptop
power supply! It worked fine.
Now I have a MPPT solar
controller which does it once a month.
Check the water
BTW, I'm Norwegian !