Q: Flat battery

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After being parked for one hour my car wouldn't start and RAC had to replace battery. I have a feeling that I had left the ignition key in the 3rd position as when I came to start the car I noticed all the lights were on on the dashboard. I had been asleep for a while and I don't know why I would have left the key in that position. My question is - could that have been the cause of the flat battery after just one hour?

Hi There, It may be possible that you may have had a weak battery that may have been on the brink of dying depending on the age of the battery. The other possibility may have been that you have a failing alternator. As you may know, the alternator is responsible for charging the battery while the engine runs by generating amperage and recharging the battery while the engine turns the alternator. The voltage regulator is a unit that regulates the charging of the battery by the alternator and maintaining a certain amperage while the engine runs. When the alternator is not working properly, this may result in the battery quickly losing charge and the car losing all power as you have described. You may also notice a whining sound as a result of the bearings inside the alternator begin to fail. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your charging system.

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