GeoLane at PTD dot NET wrote:

The Harbor Freight autodarkening welding helmet with the solar cell
actually has two coin cell batteries inside, and when they get weak,
the autodarkening ceases to function Some times this happens in a
little over a year.

A fellow student in my evening welding class took his apart and
documented the repair in the following web page:

http://www.pskl.us/wp/?p=648

Very nice writeup!

Thanks, R.

--Winston