Hi,

I wondered if I could ask for a spot of advice about my car battery?

My son and I sometimes like to sit in our car on a sunny day outside the house. Often when we do this the battery goes flat. We don't have anything in the car running except that we turn the key just enough so that the alarm won't go off. The lights, radio and aircon are off. 

We have been doing a lot of driving recently so the battery should have been well charged but yesterday we sat in it for ten minutes and now the battery is flat. I've been charging it from the mains for 90 minutes and the car still won't start. 

We have replaced the battery and taken the car to our regular independent mechanic but none of that helped. I wondered if you think I should bite the bullet and take it to the Ford garage? That would be very expensive. The car is a 56 plate with about 40k miles on the clock. 

The problem started at about the same time as the cigarette lighter stopped working. Every time the battery goes flat and we recharge it from the mains, we find that the driver side window is not working and we have to disconnect the battery terminals to make it work again. 

If anybody had any ideas of what we should do, we're really appreciate it. We live in Cambridge UK, and I am female and know a bit about electronics but not a great deal about cars. 

Thanks!

To what extent would the problems that you have not be explained by a partial short in the cigarette lighter?

Is the battery a decent one of the appropriate type?

What voltages do you get

a) off charge

b) on charge (idle) with no load

c) 2000 rpm wth some load (say, front heated window)