Not strictly diesel related although oil burners do tend to use larger batteries (which need taking care of)
My Mercedes 110ah battery finally gave up this weekend, must be 15 years old as second hand when purchased as a spare. Part of it's longevity maybe down to using a permanently installed Battery Desulfator.
Its a small unit from the US which operates under charging conditions to keep the plates desulphated.
The principal seems sound, so I thought about trying one of these larger units which in essence are hand made -
Battery Desulfators
I would be interested to hear feedback on other models out there.