Hurricane II: An HP-41C Battery Pack w/ USB

[MeindertKuipers]

I was wondering if there is any news about this nice project.
I had to rebuild one of my own LiPo solutions for my HP41. Stupidly I used a 1000mAH pack that did not have protection built in (salvaged from a USB phone power pack), and it became undercharged and is now a bit thicker than it used to be. I have found little charger boards with the protection built in and now testing another 1000mAH pack. Running in my CX for over 15 hrs now. My other pack with a 500mAH LiPo (which has the built-in protection) is now still running in my 41CL at 15+ hrs.
Still puzzled about how to implement support for low BAT, maybe Hans can shed some light here, so I am very curious about his design.