When I start up and run Megane 1.9DCI the battery light comes on.
Then after about 10 miles the dash stop light comes on.
Run Megane for about 3 hours and battery is flat. This is a new battery.
I have re-charged the battery.

Lance Boden., February 2009

need your alternator tested regulator in it could be shot ie not supplying enough voltage to the battery. [a good alternator can maintain a supply of 14.0 to 14.5 volts]
[put a D.M.M across the cars battery terminals and measure the DC output voltage,with the engine running] ANY LESS THAN 13V
REPLACEMENT alternator is required ,
most replacements from a motor factors carry a 12 months guarantee

wirecutterman, February 2009