Welding helmets and cool shades

Anyone here know how welding helmets are supposed to work? I’m talking about the ones that darken when you strike up. I have two here that were OK when new but don’t now. I can’t see that they take batteries.


They have a photo electric filter to sense light and dark and a lot have a non-replaceable battery.
However I have a Draper one that is fully automatic and does not have a battery, I think its solar powered.

I have one I bought from Lidl, It does need batteries, 2 aaa batteries up inside the helmet above the window. The +ve & -ve markers are the wrong way round on mine which confused me for a while.

Sounds like I’d better look a bit closer at the two that I have then. Thanks.