Faraday Cage..
Gun safe?
Are dry cell batteries vulnerable?
Don’t forget the tin foil hat!
Actually, I do expect something to happen as the magnetosphere which protects us from these blasts is decreasing in strength. Earth’s forcefield is becoming weaker. However, I always love to add a little humor to the topic.
Don't know about batteries but I think a good gun safe might work if it is well grounded. I'm sure we have Freepers who know for sure.
Make sure it has a mechanical lock.