car battery trickle chargers

Could be - although most wouldn't connect a charger to a battery which is already gassing.

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Dave Plowman (News)" saying something like:

Never underestimate the stupidity of the public.

My ex-landlord, one Julian Knuckles (yes, really) inspected the electrolyte level in his car battery, which he was charging, by the light of a cigarette lighter.

The hospital saved his sight.

Er - I doubt many people would be aware that it's even explosive.

Grimly Curmudgeon pretended :

Yes - there is no connection, until you press the button and the button does nothing until it senses voltage from the battery.

My feeling is the risks are vastly over stated. The one explosion I know of personally was in a garage battery charging room many years ago where a mechanic - who should have known better - disconnected a battery still on charge and the spark caused a bang. It was an old poorly ventilated area - wouldn't be allowed these days.