7 series battery problem

hi all i have recently been having trouble with the battery on my 728i, leave it a couple of days and its dead but put a charger on it or jump leads and it starts straight away ?
strange as it says the battery is sound is it a computor problem

http://www.meeknet.co.uk/e38/E38_Battery_Drain.htm

thanks m8 most informative looks like my problem is lack of use i only use it weekends and only for small distances , i have a good battery charger so looks like i will have to charge it once a week , by the way your 740 looks fantastic regards len