Flat battery
Q My problem is a 2000 VW Golf GTI. If I leave it and go away for four days or more, when I return the battery is completely flat. I fitted a new battery a year ago and it was just the same. I do leave it on a trickle charger – the car is not used every day – but it seems to have a drain somewhere. I have cleaned all the connections I can see and even went inside at night to see if any interior lights were on, but they were not. The vehicle is main dealer serviced and they can find nothing wrong. Brian James
A I am assuming that this problem was not apparent when the battery was first fitted a year ago. As you use a trickle charger, the battery should remain in a state of full charge. You do not mention the charger or the charge rate used, but my only word of caution would be that if you are not using a modern smart or regulated charger you may be cooking the battery.
The most likely cause of the problem is a drain on the battery from somewhere in the vehicle. You have checked the interior lamp, but I would also check the boot light. The easiest way to do this is to remove the rear parcel shelf and look in through the rear window.
Although unlikely in your case, I often see Volkswagen batteries flattened by leaving the indicator stalk in the ‘On’ position while the vehicle is stationary. This will leave the parking light illuminated, draining the battery.
Having eliminated the problem as being a light, the next most likely cause of the drain is the audio system. You can approach this in two ways: either remove the radio fuse from the fusebox when leaving the vehicle to see if this resolves the problem, or else carry out a current drain test. You can do this with a small 5W test bulb.
Before carrying out this test, ensure you have the vehicle’s radio code and ensure the interior lamp is switched to the ‘Off’ position. Next, remove the battery earth terminal and connect the test bulb in circuit between the battery earth terminal and lead. The vehicle systems will need to power down, and if the bulb is still glowing brightly after 20 minutes, pulling each fuse in turn should reveal the circuit causing the current drain by dimming down the bulb.