Battery Draining

[ChamRider]

Hi all.

I have a 2001 1.9tdi A3. I am having a problem where the battery is being discharged overnight. The battery is brand new so definitely not that. When driving the glow plug light is flashing. These 2 problems have occurred together so I am assuming they are related.

Would changing the glow plugs help? Could it be the glow plug relay?

The brake lights are all working and there is no fault code.

Any help or thoughts would be greatly appreciated.

(On another note - for the purpose of buying parts on line n- how can I check if the engine is 90ch, 100 or 110ch? Or does it not matter)

Thanks

[NickPicks]

I'd start with a fault code scan to see if there's anything stored.
Then I'd connect an ammeter between the battery and the battery lead, and see what the current draw is. If a 78Ah battery is going flat from fully charged overnight, then you must be drawing around 6 amps!
I'd then start removing fuses 1 by 1 until the current drops to almost zero (although you'll still be drawing power for the interior light if you've left the doors open to get to the fuses). Then see what that fuse powers and check that circuit for short circuits, stuck relays etc.

Another thing to think: are you sure that the battery is being charged? With the engine running, there should be about 14 volts across the battery terminals, with the engine off, it should be around 12v.

The glow plug light flashing may indicate a faulty glow plug - if the glow plugs are constantly on, then that would flatten the battery quite quickly.

On my A3, the car can be left for about 3 weeks and it still has enough battery power to start the engine.

If you look in your spare wheel well, there should be a sticker with your engine code. This sticker should also tell you the kW power of your engine, which you can convert to PS/ch/bhp

Get the battery tested too - just because it's new doesn't mean it's not faulty. My local car parts shop sticks the tester on all batteries as he sells them just in case they've been lying around for a few months and have gone flat / faulty.

[crackpotterpig]

i would look at the simple things first boot light, glovebox light 6 amps is quite a high draw so it must be a lamp or similar.

[ChamRider]

If you look in your spare wheel well, there should be a sticker with your engine code. This sticker should also tell you the kW power of your engine, which you can convert to PS/ch/bhp

Thanks for that - good to know

[ChamRider]

So - just to update - the plot thickened and the immobiliser was causing problems. I had been given a new key from the garage but it would not start the car. After trying various methods to get it to work, my original key also stopped working (immobiliser light flashing)

I then tried keeping the ignition on for an hour (whilst connected to a charger as the battery was still draining) - gladly enough this fixed the problem and the immobiliser light now switches off after a few seconds. It also seems to have cleared the glow plug light/battery draining issue.

My original key no longer works (immobiliser light flashes) but I don't want to mess things up again so will live with just 1 key.