In a S.H.T.F you don’t want to be under the influence, You need your mind sharp to deal with any threats. I would not want to hurt my self then take something like Vicodin and try to use a chain saw to clear a down tree. I can charge this with my solar panel’s.

I think this is a great long term solution for me. ask your Doctor if it would work for you. It is the best 35 bucks I have ever spent.
http://amzn.to/2skGiG4