@struth Thanks for that. It was overcharging that worried me. So, as long as it is 5V it won’t overcharge. That’s great. It’ll hopefully be charged enough when I get in car but good to have a standby just in case.
@ajn The device I’ve got does have a camera. And even though I prefer my old wet film Pentax, I’ll not be averse to using the electric thingey if I spot something snappable. It’ll be a bit like using film as well – battery is so crap that it will manage 36 snaps and then give up like 35mm roll!