The hydrogen will vent but the oxygen will sink down giving you a high concentration. Oxygen will start fires and the two oxygen and hydrogen mixed will go bang. When cutting steel with a torch the oxygen is what does the cutting. It can get over 5000 degrees. The only thing hotter on earth is lighting.
I work with inverters on big UPS systems and they use special chargers to charge up the batteries after a brown out. I know the difference but have used the inverter word for years and it’s hard to stop!
I know of a person who used batteries for welding! One day he came in to work with acid burns on his arms, neck and face. Asked him, “been welding?” He answered yes but the worst is I burnt down my house! He would take two old 1000 amp hour batteries put them in series and weld with them. One day he was welding and got the rod stuck and there was a big bang soon after there was fire going up the wall. By the time the fire department got there the house was half gone.
The batteries got hot enough to start wood on fire. What do you make your tear out of?

Chuck