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I had a 1995 BMW 520i but I have since (Feb, 2013) sold it to my daughter. However, over the last couple of years I have had probs with the battery going flat. At the AA's advice about mid last year I got one of those calcium batteries. Earlier this year I started having flat battery probs again. I took it back to the local AA battery people and they recharged it. My daughter rang me this morning. It had gone flat again.

In both instances (prior to returning it to the AA dealer to recharge) we are pretty certain that nothing is being left on to flatten it overnight. Since we first started having the problem, we have been very vigilant about this. Any advice please as I feel like I have just handed the problem on to my daughter.

If the battery is testing good then you could have excessive current draw from one of the electrical components. You need to get the vehicle to either a reputable Auto Electrician or the BMW agents to do a current draw test. One of the vehicles electrical components can possibly have an internal fault and be drawing the battery flat overnight - just like leaving a light on.

The alternator should also be tested to ensure the charge rate is sufficient.