Take it back to Halfords. Being flattened once and re-charged straight away shouldn't cripple it but it won't have done it any good. How long did it stay flat for? They will test it at some point to determine what killed it but doesn't it have a 3 or 4 year guarantee?

Edited by kiss (keep it simple) on 18/09/2015 at 10:02

The plates will sulphate if the battery is left flat for any length of time - even a few days can significantly harm them. Some designs are more resistant to this than others, but this is a matter of degree.

As kiss asks, how long was it left flat for? How did you charge it thereafter - did you bring it back to full charge or just put enough into it to get the car started? If the latter, you may well have been driving around with a *nearly* flat battery, which is not quite as bad as leaving it flat, but is going to inflict further damage.

You mention other flat batteries - is there some set of circumstances which leads this to happen regularly?

Edited by steelghost on 18/09/2015 at 11:55

Bought a Yuasa battery for my Audi A8 4.2 (1999 D2) at Halford UK with lifetime guarantee, £179 in 2018. 18 months later, it started going flat. The car was used every other day for local use. I was on my way to North Wales and filled up 6 miles from house and paid for fuel and click. Battery flat!. Found a guy who let me use my jump leads and of I went.Over 400 miles driving over 3 days... 2days later flat.

Took it back to Halfords where the indicator showed that it was charged. Asked the young lady to start it up. Click. Flat...

This was in October 2019. The battery was replaced on the spot, but Halfords had stopped doing lifetime guarantees but pledged to continue their 'contract'.

Its now April 2021 and guess what? The battery is going flat after 2 days.

My local garage who used to sell Yuasa batteries has stopped selling them because of the same problems and with 2 jump starters could not turn the engine over.They had previosly checked that the alternator was OK and very kindly took the battery out and loaned me a vehicle to take the battery back to Halfords.

Its a good job that we couldnt take the car back to Halfords because I was told that they had to charge the battery overnight and I would have had to get a taxi to get home.

I am pretty sure that tomorrow they are going to say that there is not anything wrong with the battery.

I am not sure that my 1999 Audi A8 D2 4,2 is maybe not suitable for Yuasa batteries and my Vagcom diagnostics has not come up with any faults re draining the battery from the alarm system or anything else.

I am most definitely sure about a couple of things.

There is no way a Yuasa battery, brand new or otherwise will ever go in my beloved A8.

In July 2021 I will have had it since 14 years.

I wiil NEVER EVER spend money in Halfords again.

No dispespect to the poorly paid young people who work there

IE we all know they are not value for money, but open on sunday.

At the end of the day..

BEWARE.

[Edited to remove unverifiable implied bad business practices which are not relevant - Xileno, moderator]

Edited by Xileno on 17/04/2021 at 12:52