Is old/flat latitude battery safe to charge?

I just got a J79X4 battery for an e6230, and while it appears to be genuine, it is a few years old, and completely flat.

I'm not too bothered if it won't have full capacity or less than the ideal cycle life, but what does concern me somewhat was that the pack is around 7.5V, which for a nominal 11.1V (3S) battery is ~2.5V cell. That does seem disturbingly low for lithium chemistry, though the BIOS reports it as 'healthy'.

A short test with Batterymon showed it charging at a low rate (~200mW), and if it is genuine, I'd assume the protection in it wouldn't let it charge if the cells were dangerously discharged.

Would anyone know specifics of when genuine protection does prevent charging?