On 9/17/2016 11:18 AM, wrote:
This is the link with the instructions:

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

I'd have tried to put 3VDC thru a 1K resistor into the
dead one for a couple of days to see if it charges.
If it does, stick the helmet in the sun for a day or so.
DO NOT TRY TO QUICK CHARGE IT.

Mine's been in the box for about a decade. Just tried
it and it seems to work, but the next time the sun shows,
I'm gonna set it outside in the sun for a while.

One thing that concerns me is that you're putting 4.5V
on a 3V system. Have no idea what does to the phase
shift of the liquid crystal and how that affects the
attenuation of the light. It's unlikely that
it's a problem, BUT, it's your eyes and a mistake
could be very costly.
Tread carefully while you can still see.