Originally Posted by boevermann
Thanks A32Deuce and kenandterry. I had just enough doubt after reading that charging batteries gives off hydrogen gas. Just didn't want a Hindenburg moment to "upset" the neighbors and be the lead story on the local evening news.
The whole idea of a multistage charger is to limit the charging current as the battery fills to limit or best case eliminate hydrogen off gassing and keep it at a generation rate so it remains in solution as hydrions (ionized hydrogen atoms).
Excessive off gassing ("boiling") is a sign your batteries are being charged faster than they can accept electrons; this is bad. The excess electrons bond with the free hydrogen ions and become H2 (gaseous Hydrogen) and off gas (vent) The sulphate part of the sulfuric acid then remains on the lead plates permanently reducing capacity.