Before taking the risk of doing something that might cause an explosion
it is a good idea to acquire the knowledge humans have gathered about explosions
.... since some of that knowledge came “the hard way.”

On lead acid batteries it is good to learn about:

the tool “battery hydrometer”
specific gravity range of cells
finding “weak” cells
finding shorted cells
when to drain a cell and refill with distilled water
what chemicals can help remove sulfation deposits

in the old days miners and submariners needed to know lead acid battery science

Today a small group of solar panel owners own lead acid battery banks and end up learning the science

Tony does not seem to be
an old submariner,
old industrial battery field representative, or
modern day solar power enthusiast.