On Fri, 12 Oct 2007 20:42:32 -0700, John Larkin wrote:

They were used, ca 1920 or so, as cheap, home-made battery-charger
rectifiers, for people who couldn't afford tungar bulbs.

I've also seen old ham literature that mentions medium-voltage bridge
rectifiers built from series strings of lead-aluminum cells. At a time
when each tube cost a fortune, a rectifier you could build from scrap
materials was a godsend.