This labelwriter is a marvel in the lab, but there seems to be no low voltage supervision for the LiPo, so they tend to be dead after a few days of not using the device and LiPo do not like at all to be drained totally. I gave it a try with GoldCaps (0.68F/5V5) as I had some left over from another project. But they seem to be too small and voltage drops too low during startup of the device, when connected to my dell M4500. I have to get 1.5F or so. When using the 2A power supply/USB charger it works, but that was not the idea. Two caps in series and 3 of them in parallel.
Goldcaps used: Panasonic Ultracapacitor 0.68F 5.5 VDC, EECRF0H684
Initially I intended to use 3mm self-cutting plastic screws but I could not find any in my workshop so I sued M3 countersunk screws. Had to machine the countersinking somewhat and drill holes and cut threads. The outline dimension is also at the upper limit (the same is true for the original battery pack). Some sanding here and there and it worked. The contacts are made with self-adhesive copper tape (needs a quiet hand and tweezers). An update will follow for sure.
Why the outside of the pack is like woven fabric, I have no clue, was definitely not my intention.
Use at your own risk!