Why am I getting a battery charge failure warning light in my Rover 75?

I'm having battery charge problems with my Rover 75 CDTi. I get dashboard warnings that all go away when you charge the battery, but return twenty miles afterwards.

Is it safe for a battery to be permanently connected to a mains charger?

Is it safe for a Honda Jazz battery to remain in the car and permanently connected to the mains via a smart charger through the winter?

Is it safe to connect a battery to a 'smart' mains charger all winter?

I see that you replied to Brian Joslin's question "Is it safe to connect a battery to a 'smart' mains charger all winter" in the negative, but I thought that is exactly what they are designed to do (although...

Changing a battery on a 3 Series - Do I have to use an approved battery?

The battery on my 2007 BMW 325i is no longer holding a charge properly. With previous cars I've changed the battery myself. However having looked at various forums it seems the car may need re-programming...