Re: Not used for a couple of weeks = Flat Battery
Originally Posted by
Percy Vere
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Our Sainsbury's had petrol at £1.059/lt this morning. I can't remember the last time it was so cheap.
Re: drained batteries. Friends of ours bought a brand new BMW 523i, delivered to their home by BMW, superb looking motor. They put it in the garage, locked it up, and went on a 2 week holiday as previously planned. Returned home, and the next day D went out to the garage to go for a spin and, clunk, battery was flat. During the 2 weeks they were away, the alarm system, immobiliser and sundry other electronic gizmos within the vehicle had drained the battery because they are NEVER switched off. Needless to say, D and H were not best pleased and had a real go at their BMW agent.
It's all to do with what is called the 'body control system' , modern cars have several computers each doing a particular job, my landrover has two, my previous car, a Citroen, had three! They handle various things, from traction control and engine management, controlling fueling and emmissions and such, right down to locking and immobilising the vehicle. One of them controls power management and in mechanic speak, 'puts things to sleep' at various times. initially, when you turn off the car it shuts things off like aircon and heated seats, as time passes it shuts off other devices.usually if you leave a door open, it will turn off the interior light after about twenty minutes, as another part of the system goes to sleep,eventually, only the security system is left active, and the clock and radio memory, even the central locking is put to sleep, it's only reactivated as you open the vehicle, trying to open it, turns off the alarm, a split second later it 'wakes up' the central locking.
One important word of caution about jump starting a modern car, do not leave the keys in the ignition when you connect the jump leads, the car will automatically lock as it senses the power!
A mate of mine had a new Mercedes, he'd not used it for a while as it was winter and it stayed nice and dry in the garage. When he went to start it the battery was flat, so he borrowed my leads, I have some really long heavy duty ones, he connected them to the Merc and took the other end out of the garage to connect to the other car, to get out he had to shut the Mercs door, he attached the leads and heard a clunk, he then found out that it had locked, with the keys inside. it took him ages to find the spare set as he'd put them away 'safe'. he was lucky he had a spare set.