New battery wont hold charge

[twist123]

Hi All,


A4 B6 130 wouldnt start a week ago, checked battery and it was the original Audi part, so thought its time to change.


Bought a new Bosch S4 fitted and all was fine when I drove it daily, parked it Friday and left it till this morning (Monday) and when I started it the low battery (brake symbol) came up and it sounded sluggish when starting.


Hoping someone can recommend me a few things to check, so far I need to:


Check the black box on the positive terminal
Check alternator cables arent corroded
Check if Hazard light stays on
Check battery voltages when running and not running


Can you guys think of other checks I need to do?


Thanks in advance

 

[Mike B]

Who fitted it ?Did they clean and tighten connectors.Had the old battery gone flat?If so you may have other faults which caused that eg alternator not charging

 

[twist123]

Morning Mike, I fitted it, contacts are clean, connectors are tight. Old battery went completely flat, no central locking or anything, it was a Monday morning and I needed to get to work so once I saw the old battery was original parts I assumed that that was definitely the issue but now realize it was probably part of another issue.

 

[twist123]

Thanks for the responses.


Had a garage check voltage, had 14v while running, 13 and decreasing till 12 something when turned off, so seems alternator is fine.

He had one of those light up screwdrivers and it lit up so somethings pulling current, but he couldnt measure the drain as never had the correct meter. I tried pulling a few fuses but nothing put the light out. I wouldve thought this would be (A) because the car pulls a little current anyway or (B) I pulled the wrong fuses. Guess I need a voltmeter to find that out.

Any other ideas guys?

 

[Cadger]

Apologies not wanting to offend but none of the interior lights are left on are they??

The 2 lights in the boot are turning off when the boot is closed?? Simple things like this can drain a battery relatively quickly....Have you made any changes to the stereo or alarm prior to the first battery going flat??

 

[twist123]

None taken, I know how sometimes it can be the simplest things, but I did check, I also climbed into boot via rear seats but theyre also off.

No changes to stereo or alarm.

Only thing I noticed months ago was I have no radio reception which I know is the antenna amp, so wondering whether thats the drain, but weather was warm then so it may not have pulled enough voltage to bother the battery, now its cold. I pulled the radio fuse and screwdriver still glowed but perhaps thats it.

 

[Mike B]

Could be the time to have a Vagcom?

 

[twist123]

The antenna throws up a code when I scan the radio, but nothing else does.

 

[quattrojames]

It's always possible you bought a duff battery?

 

[twist123]

Guess so but probably highly unlikely as it was from Eurocarparts.

 

[aragorn]

Well charge the battery and see if it works again.

If it does, its unlikely to be the battery itself, and far more likely that both batteries were drained by the same fault.

You need to put an ammeter in series with one of the battery leads and then investigate the power drain. A light up screwdriver isnt going to tell you anything.

 

[twist123]

The battery never ran completely dead, luckily the car did start after displaying the brake symbol (just sounded tired). After driving it charges really quickly as my 20 mile drive to work charged it to 12v according to garage (14v when idling so alternator should be good).


After driving and parking overnight, the car started perfectly fine this morning, but thats pretty normal, its only when I leave it 3-4 days it sounds tired, so it must be discharging. I took out the 20A radio fuse last night anyway, btw checked and hazard light does go off.


I didnt think that screwdriver trick would, as apparently the car drains 50 milliamps anyway so the stupid lights always going to be on. Can anyone point me in the direction of a multimeter on Ebay (cheap if possible) that wont blow up when checking the fuses for drain?


Thanks again guys

 

[marktdisport]

you fixed this yet m8y got a m8 whos got a 04 130tdi se which drained the battery, fitted new battery 2 weeks ago and it's drained it again, told him to get it on vagcom..... to check the aerial

 

[twist123]

No such luck, left it over the weekend without radio fuse and its dead again, becoming really frustrating. Anyone know how to check the convenience module using vagcom? Any other checks I can do using Vagcom to check for drain?

 

[twist123]

Just pulled 01562 - Right rear door cant unlock, not sure if its relevant though. Door does indeed lock and unlock.

 

[twist123]

Right, used a multimeter, drain is at 0.80+ amps, did the fuse thing and fuse 1 (aircon) is pulling about 0.20 amps and fuse 15 (instrument cluster & navigation) is pulling about 0.30 amps. Nothing else is really draining any currrent. I dont have navigation but annoyingly I dont know whether its the instrument cluster or supposed navigation so not sure where to look, as instruments all work fine, I have tried a new fuse, still drains, when I pull the fuse I get a message at the mileometer 'fuse'.

My aircon compressor is knackered so Id imagine I can just pull the fuse or will it affect my heater and climate?

Any help much appreciated.

 

[aragorn]

0.8A is waay high.

That said, you need to open the door to pull fuses, which means all the interior lighting, convenience module and cluster is going to be powered up?

 

[twist123]

Correct, I removed fuse, closed door and waited for the cluster display to turn off and turned off all interior lights, then took the reading in the hope it would be accurate, not sure if the readings are high because the convenience module isnt turning them off due to the car not being locked.

If I take the reading off the positive in series with the immobiliser on I get the same reading except the alarm goes off. Sigh.

 

[twist123]

The plot thickens. Voltage when off 12.4 voltage when on 14, voltage with load 13.9 so alternators okay. Checked drain after locking car and waiting for convenience unit and it dropped to 0.09A, much better. Cant believe that would drain a new battery in 3 days.

 

[twist123]

Whats teh safest way to disconnect the alternator overnight to test diodes?