Key Learnings:

Always stand clear of batteries when any type of motor is being started from battery(s). At these times currents in the order of many 100s of amps are being supplied from the battery.

No battery should be considered maintenance free.

All batteries have maintenance requirements, which include regular inspection and timely change out.

Consider the age of the battery, they do not last forever.

A battery change out program should be implemented to address this causal factor.

For larger set-ups, with multiple batteries like UPS systems, hydrogen monitoring warning systems should be installed.

These mishap can also happen in ¿sealed¿ lead acid batteries, so do not feel comfortable with these types.

Batteries should only be charged in a well-ventilated, safe area with the caps unscrewed.

Never store batteries in a sealed, acoustic enclosure or in the stagnant corner of a garage owned by a DIY welder