Any question answered...

They're Trustfire 900 mAh 3.7V batteries (2 of), which are Li-ion, and have integral protection PCB's.

I've no idea of how many charging cycles they're meant to take- but I was leaving them alone for 3-4 months at a time last year, which was ace.

Now, they don't last a week and that's rubbish.

Lithium batteries are temperamental things. It is common for them to go dead if left for a long time and no longer able to hold a charge. Sometimes putting them in a freezer can bring them back.