Battery drains in half hour.

[martb]

Hi folks, been reading the forum for a while now unfortunately i cant find the answer to my problem already on here so this is my first post.

Last night I had to jump my car (98 A4) I drove 10 or so miles to my GFs. Got there switched the engine off and started it again no probs, 2 hrs later about to set off and again no power so jumped again.

This morning I jumped it yet again Took it out for about 30 miles, called in at Manbat to price up a battery and asked them to check it, they said my batterys OK it read 12.7 volts. So I drove home and 30 mins later its dead again.

So I have a problem with my battery draining completely in less than half hour. Could this be a short or something?. Im presuming if it was a boot light thats staying lit or similar it would take a lot longer to drain??.

Any advice appreciated. Cheers.

[ini]

It sounds daft, but are you sure the battery is being drained?

When you experience the problem are the headlights very dim/wipers slow.

Does the starter try to engage at all.

Do you get any dash symbols coming back on (immobiliser etc)

It sounds like your battery and alternator are ok, do you have access to a fault code reader or VAG-COM.

Have you noticed any burning/scorching smells, as that is a lot of current flow for such a heavy duty battery to drain in half an hour

[martb]

Just tried windows and wipers they are working although slowly and radio comes on. But that seems to have drained it a bit further as now its just clicking when i turn the ignition rather than trying to start it. No burning/ smells or dash symbols. Cheers ini.

[AutoTDI]

How old is your battery? Is it more than 5 or 6 yrs old? A voltage check is no indication of a battery's ability to hold a charge. My time honoured method of testing a battery is: does it start the engine easily after standing overnight? If not, swap the battery.

[martb]

Id swap it in an instant and thank my lucky stars if I thought that was the problem. Thats why I double checked and called into Manbat.

It was showing absolutely no signs of packing up, started instantly every morning. Then bosh, nothing

[ini]

AutoTDI's advice is sound, either replace your battery, or disconnect the suspect (charged) battery overnight, and see if it has held its charge in the morning.

If it is partially discharged, the battery is the problem.

If the battery is not at fault, and you can not locate the drain/short, use the multimeter (or 12v bulb in series) at the battery and pull each fuse/relay until the drain stops (12v bulb goes out).

Once you have narrowed down the search to a single circuit, test the most likely components.

The most common culprits apart from the boot light are dodgy relays causing motors/pumps to continue running.

Can you hear any noises with the ignition off?

[AutoTDI]

It was showing absolutely no signs of packing up, started instantly every morning. Then bosh, nothing

But this is often how batteries fail; one day they work, next day (usually a cold one) they don't. If the battery is less than 3 yrs old, claim under warranty. If warranty expired then a new battery is the answer.

[Fettler]

Loose connection or bad/dirty/corroded earth connection.

[martb]

Loose connection or bad/dirty/corroded earth connection.

Would that drain the battery that fast?

[Fettler]

if loose could give/cause symptoms of things working slowly especially the starter motor.
Have you actually had the bonnet open whilst someone cranks the engine? Sometimes you are lucky and see a loose connection spark under load.