Strange issue with Battery

[Zaquria]

I have a Toyota Avensis 2005 2.2 d4d

Over the last couple of years I have had an issue with the car Battery being flat, so far we have had 4 different batteries (The first three were the wrong size for the car) put on the car and yesterday went to start the car and again, dead Battery and car wouldn't start.

When I try to start the car, it turns over followed by a series of clicking noises. The Battery is flat, as the dashboard lights come on and then go off as soon as I try to start the car.

We have had the alternator, starter motor and wiring checked and the garage can find no faults.

However, I did notice that these last few days, the car has been "sluggish" to start and would take about 3-4 seconds to actually start.

Anyone have any idea's why this would keep happening?

[Mike169]

Hi.

Two comments.

Toyota do a fixed price for the Battery and fitting priced at £125.00, a bargain as it is a very big Battery.

Do you have a multimeter and if so disconnect the black earth Battery lead, and if you know how to use the multimeter you can detect any large battery drain on your car. If you do the disconnecting of your battery beforehand wind the windows down, open the drivers door and keep the keys in your pocket.

Regards, Mike.

[sproutdreamer]

I had the boot light staying on and draining the Battery. Easy to drop one of the seats and see if it stays on. Problem is it may stay on intermittently so hard to diagnose. These sort of problems are a pain and take time - Good luck with it!

[Mooly]

You need to be sure that the original test of the alternator wasn't just a quick check to see if it produced sufficient charge but that it was also tested for leakage as that is a fairly common cause of batteries mysteriously going flat. Typically it will be a leaky diode in the rectifier pack within the alternator.