Originally Posted by Benny
Renault class the battery as a wear-and-tear item, so it's not a warranty item.
If the alt is damaged, it's a good idea to replace the battery at the same time - as I said before, a regular car battery is fairly intolerant to deep-cycle usage, and will be unable to hold as much charge as it would do normally.
Firstly, try and follow the regime suggested by Benny in an effort to identify the fault.
If the latter is the case, wouldn't it follow that the failure of the alternator has caused the battery to fail and render it "consequential damage" which should be replaced under warranty???
I would claim notwithstanding; I would expect a new battery to last longer than 12 months and, I can tell you that no amount of tiny light bulbs inside the car should drain a decent-rated battery in 2 hours. People do clean their cars for hours on end and they are not expected to disconnect their battery when they do so; if this situation is prevalent, then the battery supplied is not fit for purpose, don't you agree?
You may find that there is a short circuit somewhere that drains the battery regularly and the doors open for 2 hours just exacerbated the problem. In such a scenario, the problem is not fair wear and tear on the battery and the replacement battery would soon suffer the same fate.
A trickle charge on your present battery may last longer but if the plates have warped enough to come in contact with each other, I'm afraid it is dead. Talk to Renault, but don't expect them to say ok straight away... so be prepared to argue your case. Many years ago, when cell-to-cell links were exposed, you could sometimes bridge over the bad cell and work happily away with 10.5 volts, but not nowadays sadly.
Of course, Renault might not tell you if they find a short, so you may need to have it tested independently.