No electric power for charging makes that a one use purchase.
It uses very little power; and I can charge the battery via USB, via a solar panel; and it is reported that a single charge will last for days.
Just for that I popped it open. It has a 3.7V 3000mAh battery. I have a whole box of Chevy alternators from the '60's and '70's, a large box of V-belts, and several bicycle frames (that I'm holding in case I need to manually power my grain thresher and my
sorghum press) I could easily make a leg powered charger, should I lose my solar panels. If an EMP takes out my box of alternators. I have enough scrap Al, Cu, and NaCl lying around, that I can make my own battery. I have enough scrap Al, and Cu, to power the thing for the rest of my life.
About 20 years ago, I read the transcript of a dissertation that was given by an economist at a University. I wish that I could find it again. I have searched the internet long and hard to find it again, with no success.
This man had defected from the Soviet Union, and got his degree in economics here in the US. When the Soviet Union collapsed, he was able to go back home to visit friends and family. He said that the Soviet economy was very similar to the US economy; and that we can learn from what he saw in the wake of their economic collapse.
I learned much from his dissertation; and one of the key things that I leaned was that when an economy collapses; we have to find new ways of doing things.
One of the things that he mentioned was that nails became a very valuable commodity in the wake of supply chain issues. Nails are useful for building things that one wouldn't need if one had electricity, and one could just go to the store to buy what he wanted.
If we face economic collapse; we will have to find solutions that might not resemble our normal way of getting things done.
I love to shop at Goodwill. I can buy technical books there, that no one seems to want. I can buy a book for 1 dollar, that would cost me hundreds of dollars if I was taking the college course.
One of my prized finds is a book on how to engineer a steam boiler. I have no intentions of building a boiler; but if the the power grid, communications, the supply chain, and the internet are down indefinitely; I have all of the information that I need to build a steam powered electric generator; and it only cost me a buck.