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Although I've been a member here for a few years , having had a few VAG cars myself , these days it is mainly for knowledge relevant to the various VW cars run by family members . My daughter has had her Polo 9N for almost three years - it is a 52 reg 1.4 petrol automatic car . While the car generally runs well , it has had one ongoing problem , that the battery often runs down to dead flat . I used to largely blame this on the fact that my darling daughter hardly drives the car , tending to pinch her mum's new Mini whenever she can , rather than use her own petrol !! The upshot of this is the car can often sit for a month or longer between getting started , and then she might only go 5 or 10 miles in it ! There was only something like 340 miles between the last two MOTs . This is her first car and I've told her since she got it that she needs to use it more . However apart from this one issue the car hasn't given a moment's trouble . Anyway , with recent events , I've spent the last few weeks around the house more than normal , so I decided to give the car a bit of an overhaul ; I was aware the exhaust system was on its last legs and fitted a complete new system ; also conscious that the battery repeatedly being allowed to go flat wasn't a good thing , I treated her to a new 63Ah Bosch S5 battery , thinking that , along with a bit more regular use , might solve the problems . All was well for the first couple of weeks and she reported the car was going great . Pleased at this I felt it was money well spent . But then the other day , she told me she'd parked the car up on Wednesday , and on Friday it was dead flat again . She was going to get her step dad , who knows nothing about cars , to charge the battery , but I told her to leave it so that I could see for myself , and I went up the following morning ( last Saturday ) . As Gill had reported , even the remote central locking wasn't working and we had to open the car with the key ; there was no sign of lights having been left on , so I opened the bonnet and measured the battery voltage : zero ( and I have a decent Fluke auto ranging DMM which will register quite small voltages . Anyway , I had brought along another fully charged 100Ah battery out of my Mercedes 300SL , which i knew to be good , and jumped it off that , leaving the donor battery connected for a few minutes before attempting to start and also after it , to avoid too much of a drain on the alternator . We drove the car the 10 miles or so to my house and parked it up while I ran Gill back home and then did some shopping . Some two of tree hours later , I went back out and checked the voltage ( it had been showing 12.7 V when we parked it ) and was down to 5.1 V ; admittedly it had only had a 20 minute run , so would not have been anywhere near fully charged . I put the battery on a maintenance charger and left it overnight , looking at the indicator on the battery charger yesterday , it was showing 12.8V and still charging , so I left it to today , when it was showing 13.3 V - more like it . Anyway , I took the negative terminal off and put the meter in series , looking at current , when I reconnected through the meter , there was a loud clunk from somewhere below the windscreen , and the wipers jumped , and of course the alarm went off . However on cancelling the alarm , opening and shutting the door so the car wouldn't lock itself again , there was an initial reading of a little over 2A , before the car went into quiescent mode and the drain dropped to circa 0.15A which I didn't think too excessive . Pulling various fuses would reduce the current by 10mA here or there , but there were no huge consumers : once I figured that the fuse card referred to the box upside down , the two main draws were the dome light , which was off , fuse 28 ; and the cigar lighter , fuse 46 , I checked the lighter wasn't warm ( Gill is a non smoker so it is never used ) and left it out of the socket , just in case it was somehow drawing current . I checked for things like a light in the boot , and the glovebox , no problems there . With the battery reconnected , showing 12.7 V before starting , and rising to 14.4 V with the engine running , I'm fairly confident the alternator is working and charging fine . I did find this thread when looking for ideas , but couldn't see any other discussion re common problems . The poster on that thread apparently had a door lock replaced by the dealership under warranty . I'm now leaving the car overnight to see what happens . In the absence of any further ideas , all I can do it to try disconnecting various fuses until I see what might be the culprit ; oh , after reconnecting the battery , I discovered there is an auxiliary fusebox inside the lid on top of the battery , with about half a dozen fuses - I have no fuse map for these and no idea what they protect , but will try pulling each of them in turn tomorrow to see if the drain might be through one of them . I don't know if there are any known common faults on these cars which might cause the battery to drain . I now get the feeling this is something intermittent , either something like a door lock not fully latching , a wiper motor not fully parking , or water getting into something and causing a drain ( but haven't correlated these events to weather conditions yet ) , we did have heavy rain last week , so that is a possibility . Any thoughts or ideas would be appreciated . Thanks in anticipation .