WHY2025 badge batteries@kitten TL;DR: It doesn't increase the risks.
Long: 18650 cells are more or less a minus pole all around except for the little tap at the end. That's +. Puncturing the outer plastic does nothing to the stability of the cell itself. The plastic is just a protective heat shrink. I have replaced it on a lot of cells that had signs of wear (a friend uses those for her vape). Big holes however expose more of the negative pole shell and with that increases the risk of shorts.
WHY2025 badge batteries@kitten I didn't get the whole story around the badge but as the battery holder is exposed I would recommend getting some protected cells. They have a little PCB with protective circuit hidden under the heat shrink that shuts of in the case of over (dis-)charge or shorts. The little dent at the end in the pic looks like those might even be protected cells? Hard to tell. If they are they should be 2-3mm longer then the nominal 65mm.
WHY2025 badge batteries@kitten however with protective cells puncturing the plastic is a bit more of an increase in risk (up to the same as a unprotected cell) as that opens up a new connection point that would bypass the protective circuit. So yeah. If it's a normal cell and you are fine with the general risk of a bare 18650 a bit of tape (or a new heat shrink) should be just as safe as a new cell. But I would recommend putting in some protected cells. Hope this helps :)
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