My battery seems to be losing .2V every day and im not sure what is draining it.
How do i work out what it is?

Put an ammeter in the circuit (in series - but don't do anything that would pull silly current - like trying to start it for instance, or you'll have a fried ammeter!) & pull each fuse in turn until you find where the drain is - assuming there is one ofcourse, it may be nothing more than cold weather & or weak battery.
A common one is failed alternater diode(s) in which case you'll need to disconnect the alternater as I doubt it's fused.

Is it a known good battery? Old knackered batteries will self-discharge quickly. Try disconnecting everything and see if that changes the voltage drop rate.

Otherwise do as Russbost says. Ammeter in series and pull fuses....

how many days? you ca nexpect a drop in voltage after a couple of hours once charging has stopped. .2 V is not that much.

if after 2 weeks it has dropped .2 V per day, then that is not good - shouldn't really go much below 11.5 V, (note figure from memory so you may need to google, but if it drops below tha, then battery is at fault or you are drinaing it.)

Just to enquire because my battery discharges too when it's standing though I dunno at what rate any more as I always disconnect it when I get back and its a good battery, one of them red and black ones who's name escapes me. When you say in series, in series where? Across the fuses?

[Edited on 5/10/09 by mistergrumpy]

It is virtually brand new. Not many fuses in the car atm so i suspect the alternator. Will check at the weekend.

Cheers