I have an old electrical book where the writer frowns on the use of lamps in series to obtain a charging voltage off dc mains- but his concern was only the damage done to cells by poor voltage control, not the safety angle! He also castigated the use by some ingenious tightwads who had discovered that there was a small voltage differential between neutral and earth and had used this free current to charge batteries or even operate the servants' bells to summon the serfs! He recommended taking accumulators to an 'expert' at a Wireless Shop, where proper facilities existed and the life of the units was thus assured. Our pub-landlord used the bulb method, ( by then ac- how it was rectified I have no idea.
In the days when children had to be parked, by law, outside of drinking dens, (while ma and pa had a small beer), fobbed off with a bag of broken-crisps and a bottle of pop, I remember we kids used to occasionally sneak round to the charging shed at the back. A faint dull red glow of several small lamps could be seen on the bench, the rest of the shed was in velvet darkness. "Child-rumour" was that 'they' kept a mad-grandmother/rabid cats/a monster chained to the wall in there, so we used to have a quick peep and run off terrified back to the well-lit frontage.
