Flat Battery...


A3 2.0TDi S Line
VCDS Map User
Jul 31, 2013
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Down South
Any ideas for me on this please guys...

Had the car for only 3 weeks and 3 times the battery has gone flat.

First time, it was left in the works unit for about 3-4 days and there was no life in it at all, after a jump start it was fine. Thought maybe an interior light was left on but they were all switched off. Even after knocking it off and on after 10 minutes was ok and the next day it was ok.
Battery seems to be good after trying a tester on it.

It was left in work again last friday, on saturday i had it running as i fitted new number plate lights. Then, tuesday morning it was dead again but with a 10 minute trickle charge it was showing it was full again.

Brought it home wednesday from work and used it yesterday for about half hour with no problems. This morning i tried it and theres life there but not enough to start up... Confused as to why it seems to be a good battery but something is obviously draining it.

Surely can't just be the cold weather???
Cold weather will seriously affect a bad battery. How are you checking it? A good battery will hold a charge at just over 12v when engine is switched off and while the car is starting it shouldn't drop below 8-10v.

Check alternator too as it may not be charging the battery properly, but your issue sounds like a bad battery or battery drain.
My boss tried a tester on it, not sure what as i wasn't there. Gonna try a local place this morning that sells batteries as i heard they do free checks for you. Hopefully its not a fault somewhere else.
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Got it checked earlier and it is the battery... £60 for a new one.

Does it make a difference with the start/stop on my car?
Reason i ask is because halfords want £149 for one that is oe quality for start/stop technology...
Start stop batteries are higher rated and cost a bit more. Your car doesn't seem that old, batteries start dying after 6 or so years. Some aftermarket retrofit accessories can cause drain on the battery if not wired in correctly. Interior lights won't be cause as they shut down automatically after about 10mins. even when left switched on.
You need to check what battery was originally fitted to your car,as Soot1 has already said, cars with stop/start technology have upgraded batteries.
Some cars just have upgraded versions of conventional lead-acid batteries , whilst others have AGM (advanced glass mat) batteries which deal with frequent starting and brake energy recuperation.
AGM batteries are expensive, the £140 from Halfords is about right for an AGM one....
Time to examine the exact specs of the battery now in your car ,presuming the correct grade item is currently fitted.......
Thanks for the replies... Once I found out it was the battery I have been chatting on another thread about them and mine is a Varta AGM so going to get another Varta, this time a silver one which has better ah, cca. Although almost double the original price I was quoted at least I know now that it will be a quality replacement.

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I had a Halfords battery on my 1.8T Golf and it had to be replaced under the warranty. The next one died after a couple of years too. Receipt lost and so I bought a Bosch S5 from ECP, No problems since. There can be some good bargains on ECP but the retail price goes up and down meaning a massive discount is not always a bargain. Do your homework before buying
Bosch S5 battery is the same as a Varta silver dynamic which are almost always cheaper than the Bosch batteries. Check out Carparts4less.co.uk they are the on line arm of ECP and 95% of the time parts are cheaper on there.

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