[avar]

Some of us enjoy fixing things like these over and above the hypothetically fungible billable hour, and whether you can substitute some time in an evening with a billable hour or three is highly dependent on your employment situation.

But in this case the relevant cost under discussion isn't that of a replacement vacuum cleaner, but what value you assign to your house not burning down due to a crappy 18650 cell, or the anxiety of worrying that that'll happen.

[stavros]

Well, I don't enjoy making the hundredth battery pack, so I'm counting it against the hypothetically fungible billable hour.

The cost should be the cost of a good-quality battery pack from the factory, which I can only get right now as part of the vacuum, unfortunately.