Having problems starting my car. I've been away for 10 days came back and the car wouldnt start. Completely flat battery. i have a battery jump starter but wasnt enough umph in it to start it but i managed to start it with jump leads from another car. went for a drive, probably about 30mins, high revs all the way went to start it again this morning and its completely dead again, not even any lights on the DIS. i've not long had a new battery probably 3 months ago.
This seems to be a reoccuring issue since i've had the car. if i leave it for around 2 weeks i have a dead battery. This is my 3rd new battery in 3 years (halfords warrenty).
Anyone got any ideas? i've checked the terminals and they seems tight, i cleaned up the earth terminal under the battery about a year ago to see if that would help. im going to try and get hold of a multi meter today but is there anything else i need to check look out for?