Board Thread:Off Topic/@comment-25396609-20160825171839/@comment-26397825-20160826045726

That would depend on how much electricity the pacemaker consumes, I think. I don't think he would have to change it regularly; a battery filled with compacted Lightning Dust rather than a crystal shaped to fit the battery would last a lot longer, and if a pacemaker doesn't really use much energy in the first place it would probably last a lot longer than the pacemakers of our world.

My suggestion would be to look at how long a battery lasts in a pacemaker in our world, and either double or triple it depending on if you're going for a crystal or compacted powder.