HP-67 battery pack disassembly

[GreyUser]

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.