battery keeps going flat

audimad23

audimad23

Member
hi everyone i've got a 2001 audi a2 1.4 se over the last month the battery is keep going dead/flat i have charged the battery about 4 times but still going flat the battery is fine as i had a new one the middle of last year i was wondering what could be draining the battery or could it be the alternator that needs to be replaced as when i was parked up the other night with the car running and lights on the lights was keep dimming i was wondering if anyone else has had this problem and if so post what this could be, Also if it was the alternator could i replace it myself of does it need to be reprogrammed to the car as i dont have vagcom , any help please post its appreciated thanks audimad23 :confused::)
 
Hi if you are doing short trips you may find you are taking more out than putting into the battery. starter-heater-lights all take power. It may be worth putting a volt meter on the battery to see what its resting voltage is (engine not running) then voltage with it running. These values will help in tracking down if the battery is dead or the alternator is not working right. The cold weather lowers the cranking power of the battery and its voltage--my tdi strugles to start at the mo so im expecting to put a battery on that soon. hope we get it sorted for you mike
 
Just because the battery is not that old don't discount it as being at fault, as mentioned check the charging rate, you should get something like 14volts, check the charge rate with all the lights heater HRW on to see that it stays up. if that is ok see if the boot light/glove box light etc are staying on, even the lights under the window switches have been known to stay on after locking the car
 
Hi Audimad23,

Have you got a multimeter? If you have, hopefully it’ll be able to test DC Amps.
This is how to check for excessive current draw, which might be the cause of your battery woes.
As the battery lives in the boot, you may want to fold down the passenger rear seat so you can access the battery and tester from the inside of the car. Also, once you close the boot, if you loose connectivity between the tester and battery you won’t be able to open it via the key fob until you reconnect.

How to test:

Remove the negative battery terminal.
Connect one lead from your tester to the negative battery post and the other lead to the terminal you’ve removed. Don’t let the removed terminal touch the battery post.
Turn the multimeter to DC amps test (10 amps test or more if possible) and then turn on the multimeter.
Turn on the ignition so the dash lights are on and open a door so the interior light comes on.
Don’t attempt to start the car or you’ll damage your test equipment.
Turn off all other accessories (such as radio, lights, climate, wipers, etc). Close the boot (take care to read above incase you get locked out).
Read the output on the multimeter, it should be around 1 amp.
Turn off the ignition and remove the key. Sit in the back seat and close the door. Once the interior light goes out the reading should be around 0.2 amp.
Use the keyfob to lock the car (while you’re still sitting inside). The reading should increase and then return to around 0.2 amps. If the reading is much higher it is likely a control unit or device is still functioning, which will probably be the cause of your battery draining.

If you suspect this is the case, you’ll need to start pulling fuses, one at a time, to try and determine what circuit is at fault.
You’ll know when you find the faulty circuit as the multimeter display will drop.
Once you’ve located the fuse for the circuit you can check to see what devices it’s protecting, which should give an indication where to look for your issue.

Of course, if you don’t see any spurious current draw and your charging circuit is working well, you’ve got a faulty battery.

Cheers

Jeff
 
ok thanks for the reply's everyone and a2sumo yes i only do short journeys so that might be the problem and i always have the stereo on and heaters lol and jeff i haven't got a multimeter but i think my friend has so next time i see him i will get him to check the battery and i have got the battery on a overnight charge tonight so i will see how it goes this week and try not to have all the heaters and stereo on at the same time lol and see how i get on thanks again audimad23
 
Only partly related to the thread, but my battery warning light flickered on&off a few times this morning (at the end!! of my usual 27m commute, as I was parking up). A bit odd, so I monitored the voltage on the scangauge on the way home, 12v-ish when I turned it on, 11v-ish when I was starting up, and mostly 14.4v but occasionally briefly dropping to 14.2v or 14.0v on the run home. The warning light didn't come on again.

Any thoughts?
 
Hi.

Jeff, are you sure about the numbers?

I have a strange problem on my car....
Been using your method to check drain and here it is.

When I connect the multimeter it jumps up to around 2 amps. the CD changer use a lot of time to check the CD's... then it goes down to around .5 amps.
I have found out that if I remove the Radio and AC fuse it goes down to 0.06amps. If I put in the fuse it goes some up, but then down to 0.06 again.
If I disconnect the meter and connect it again, it goes to 2 amps and then down to 0.06 amps again....

With the ignition on I have around 4 Amps of current with the AC in OFF. If I remove the fuse for the Naviplus unit / radio I lose around 1 amp. So 2.8 amps.
If I remove AC, Washerheater and a couple of other fuses I am on 1,5-1,8Amps.
When I turn of the ignition it goes down to .06 again.

The STRANGE thing is that my battery have been charging at around 2 amps for 2 days, and when I tried to start it... well it did not start! Battery at 10.4 V
I connected the booster, started the car, drove 500meters to my door. Then the battery was 12.someting V staying there....

We changed the battery 2 weeks ago. The funny thing is that the "dead" battery that showed me 10.something Volts when I removed it today showed me 12.4V

Could it be that both my batteries are broken?
Could it be the CCU that is unstable and sometimes make big drain?
Could it be something that is faulty grounded or making a short? But this should show on my meter...
Any ideas?? Help... someone.. please! My wife is killing me soon! :eek: :p
 
FYI - My new battery is damaged. I disconnected it from the car and after 12 hours charging the battery had 11.8Volt. Not over 12.5V while charging. And after disconnecting the charger and waiting 1 hour the battery was 10.8V without anything connected to the battery.
 
I've seem a similar problem like this some years ago. A batch of Volvo car batteries were supplied without sulfuric acid, just distilled water.....If you test each cell with an electrolyte tester you'll know if it has the correct liquid solution or not, but I suspect not.

Some batteries are shipped "dry" for H&S reasons, and perhaps this one didn't get filled.

Cheers

Jeff
 
Thanks to the tips on this thread, I pulled fuses in turn and used a multimeter to test my car's current draw; the culprits were:

Fuse 36: heater controls 0.3 Amps
Fuse 30: brake lights 0.1 Amps

Both are quite odd; does anyone have thoughts on what might be at fault? Thanks
 
What happens if you unplug you brake light switch and then measure the brake lights current?
 
GuruX said:
What happens if you unplug you brake light switch and then measure the brake lights current?
Click to expand...

I'll try that and report back, as I recall there is one fuse for the brake lights and another for the brake light switch; removing the latter didn't affect the current draw.
 
Would any fine folks have thoughts on why the heater controls would be drawing current? I've not had a chance to play with the brake switch, but as pulling the relevant fuse (for the switch, not the brake lights) made no difference to current draw, I suspect there may be an issue with the brake light circuit too.
 
sailesh said:
Would any fine folks have thoughts on why the heater controls would be drawing current? I've not had a chance to play with the brake switch, but as pulling the relevant fuse (for the switch, not the brake lights) made no difference to current draw, I suspect there may be an issue with the brake light circuit too.
Click to expand...

Do you have a "non-Audi" radio fitted?

That can sometimes cause items to be permanently live when they should be ignition fed, I would imagine. (due to incorrect wiring)

Steve B
 
Steve, thanks. It's all stock, however I will have the wiring double checked for any foul play - sometimes tough to rule out when a car has been through multiple ownerships and mechanics. Cheers
 
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