A few years ago I purchased a Lincoln Electric Darkfire Autodarkening Welding Helmet and it has worked great for me up until this week. I use it periodically when I weld with my MIG welder - sometimes two or three times a week and sometimes it sits on the shelf for a month or two at a time. I try and treat it with respect as I have heard stories where people have dropped a helmet and the module quit working. When not in use I store it on a shelf in the shop that is not heated and the shelf location does not allow the helmet to be exposed to a lot of light if the lights are not on. I mention these facts as I thought I would share some information on the module and why the helmet quit working in my opinion - lack of constant exposure to a light source. I am making this post not to complain but to educate other owners of similar autodarkening helmets (Lincoln or other brands) about making sure you store them in an area that gets adequate light to keep the batteries charged.
I tried to use the helmet earlier this week for a small welding job and it did not appear to be darkening so I did some reading as to what could be wrong with it and the most common answer appears to be the batteries going dead from lack of being charged. According to the instructions and the advertising my helmet was solar powered and there is no battery that requires replacement. They do mention not to store the helmet in a dark cabinet or other storage area for long periods - what they do not mention is this is because there are two Lithium 3 volt batteries inside the helmet that need to be charged by the solar cell array or they will eventually go dead.