I am afraid that I have no answer to help you, however I am also experiencing this issue. The laptop is just out of warranty. I am finding that when closing the laptop lid to enter hibernation at >50% battery, I return to a 'Battery critical level warning', with the battery fully discharged. 

I'm interested to know why you feel you should be doing a full discharge cycle once a month with this battery.

In the past, I've read that doing so helps keep the battery in good health. Your reply prompted me to do some more research and find out this advice is outdated. Thanks for bringing my attention to this.

Sorry to hear you're experiencing the same issue, it's very frustrating! I still haven't been able to find a fix and my warranty expired a few months ago too. I called Dell and was told it could be motherboard issues, looks like I will have to send it off for repair...will keep you posted if I find any fixes in the meantime

@eskway Any updates on this? I have the same problem.