(06-10-2022 12:23 AM)vassilisprevelakis Wrote:  just run an exacto knife around the side where the top half is glued to the bottom half. In this way you can separate the two halves and gain access to the batteries.

(06-10-2022 05:34 PM)GreyUser Wrote:  They are fused together by ultrasonic welding.

Place a welded end on a solid, flat surface. Place a new utility knife blade in the opposite, exposed seam. Hold blade with your non-dominant hand and wack top edge with a small hammer until the weld fractures. One or two hits is usually enough. Flip over, hold the now opened end together with a spring clamp and repeat on the remaining sealed end. Without the clamp, the halves will deflect open upon impact, absorbing the blow and it will not have the desired effect.

(06-12-2022 04:09 AM)GreyUser Wrote:  Excellent! It’s not as dangerous as it sounds, I’ve lost count how many packs I’ve opened and still have all ten digits, without scars. The method works for any HP calculator battery type that have plastic shells as they’re all ultrasonically welded.

Liquid styrene model cement (the water like stuff, Tenex or Plastruc) work really well, to re-close without any ooze or visible glue. Only takes a few small drops in either half. The stuff is great for any case or HP41 post repairs. Maybe not worth buying for one battery but who here has just one HP calculator?