A4 battery failure symptoms

[RSharp9999]

After 6 years the battery had had it. The only indication I got was that one day when I was sitting in the car listening to the radio I got a message "Battery low - start engine". Engine was starting ok. Then a couple of weeks later put the key in one morning and nothing. It's a very big battery because of the heated seats. I got a new Lucas one for about £80 from my local parts store. Before I disconnected the old battery I connected a small 12v battery across the terminals to keep the computers and alarm happy.

I hadn't used the heated seats a lot but am not using them now as heater is so good.

[mhurer]

Still on my original battery after 7 years and just keep thinking it is only a matter of weeks before it stops working, although it has not shown any of the symptoms you describe. Now I know if I get a message like yours I need to get a new battery, so thanks for the info.

Was it a straight swap, as I remember reading that sometimes the battery needs to be coded to the car? It sounds like connecting the 12v battery might negate the need to do this, and the car will 'learn' about the new battery.

Just out of interest what 12v battery did you connect to the terminals, and for how long?

[b206]

If you disconnect the battery all you will lose are the computer settings (MPG etc) - everything else will be fine.
Did you pick a battery with the same AHs and CCA ?

Replacing battery shouldn't make a difference to your heated seats - would just drain battery quicker ?
Yes, they need coding - some say they learn but I'm unsure.

[RSharp9999]

Still on my original battery after 7 years and just keep thinking it is only a matter of weeks before it stops working, although it has not shown any of the symptoms you describe. Now I know if I get a message like yours I need to get a new battery, so thanks for the info.

Was it a straight swap, as I remember reading that sometimes the battery needs to be coded to the car? It sounds like connecting the 12v battery might negate the need to do this, and the car will 'learn' about the new battery.

Just out of interest what 12v battery did you connect to the terminals, and for how long?

As I said I didn't get much warning of the failure - one morning the engine started as usual the next morning just the solenoid click. Luckily I was at home but I could have been at the other end of the country.

The 12v battery I used was one I rescued from the backup power supply in the computer room at work. (They are changed annually). It's lead/acid, 7Ah and 15cm x 6cm x 9cm. It has the common spade terminals and I made up a couple of leads for it with ordinary round terminals at the other end. I connected the negative to a nut on the bodywork. The car battery positive terminal has a plate attached to it with several wires bolted to it and I took the positive lead from my little battery to one of these. They are an unusual thread but I managed to get an M6 nut to tighten enough with a couple of washers underneath. I then disconnected the car battery terminals and replaced the battery with the new one. Maybe took 10 minutes.

I didn't do any coding for the new battery and I don't know what would happen if I hadn't connected my little battery and the computers and alarm were without power for a few minutes.

It is a big battery and a very awkward lift; so be kind to your back and get someone to help if possible.

Incidentally the local Audi main agent wanted £220 for a new battery and the labour.

Your car seems similar to mine - I've done 65,000. I joined the forum because I had a new problem - I was losing a bit of coolant and have now confirmed that it's coming out of the water pump. The first indication I got was that one night the heater was blowing cold and I found that the top-up reservoir was almost empty. It's a really big job to replace the water pump and no one wants to do it apart from the main agent . My first and last Audi!

best regards,
Richard

[RSharp9999]

Thanks for your note. I managed to get a Lucas battery with the same Ah rating from my local parts store. The chap there reckoned that if I disconnected the heaters in the seats I could buy a smaller battery but to be sure I got a similar one to the original. I try not to use the heated seats now but they are great if you have a bit of backache. I didn't do any coding - just made sure the 12v was there all the time.

This A4 1.8 TFSI is my first and last Audi. I had to have the complete dashboard replaced under warranty. There wasn't a spare in the country; it took a week to come from Germany ! Then a couple of years ago the fuel pump had to be replaced, an expensive job even though it's nice and handy under the rear seats. I didn't mind replacing the battery after 6 years but now at 65,000 the water pump is leaking. That's going to cost an arm and a leg as it's on the side of the engine and loads of stuff have to be removed to get at it. No one but the main agent wants to do the job.

I'm going to do another post to find out if it's got a timing belt or a timing chain. I asked the main agent last time I was there but they didn't seem to know. If top of the engine has to come of it may be a good time to do that as well.

OR it may be the time to trade it in for something more reliable. The coolant leak is still quite small.

regards,
Richard

[mina08]

when replacing the battery, you then need to recode via VCDS to tell the computer it is charging/using a new battery, this is done when changed at the dealer or if you have a VCDS cable, other wise it does not charge properly

How complicated is it to replace the battery on a B8 A4?

[thescouselander]

when replacing the battery, you then need to recode via VCDS to tell the computer it is charging/using a new battery, this is done when changed at the dealer or if you have a VCDS cable, other wise it does not charge properly

How complicated is it to replace the battery on a B8 A4?

I recently changed the battery on my car but didn't bother with the recode - everything is fine so far.

[gregpot2000]

I recently changed the battery on my car but didn't bother with the recode - everything is fine so far.

I think after a while, the car will eventually detect a new battery after a few weeks without problems. But coding ensures it knows straight away