Phones wake up about every 30 minutes or so when "powered off". Explicitly to report loction and perform background chores. So you are right. Even the removable

Phones wake up about every 30 minutes or so when "powered off". Explicitly to report loction and perform background chores. So you are right. Even the removable battery is suspect. A foil/metal lined bag does the trick. Or a chip bag: https://www.google.com/amp/s/www.popularmechanics.com/technology/amp13953308/electrician-turned-chip-bag-into-faraday-cage/ https://www.google.com/amp/s/www.popularmechanics.com/techno...