Draining Battery

blitzwing85

blitzwing85

blitzwing85

Soldato
Joined
11 Sep 2011
Posts
2,544
Location
Reykjavik, Iceland
10 days ago my car started coming up saying the battery was low and would recharge when driving.
For the following 6 days, this came up 4 times.

Then on the next evening, the car alarm was going off and when I went out the battery was dead as can be. Nothing in it at all - central locking didn't even work.

Got it jump started, took it to garage for test. Alternator OK, battery 'Good' Starting Capacity 55%

Problem never came back. for a full week.

Last night I went on a 70 mile trip and then this morning the car is totally dead once again.



Now, 1 week ago it was snowing and 0C. Last week since it has been 5-9C. Last night it snowed again and was 0C.

I know batteries are not as good in the cold but it seems for me the cold weather is completely draining it in just a few hours.
Is this simply an indication of a battery which is on the way out or is it likely something more sinister?
It just seemed odd that at 5C it lasted 16 hours not in use after only 2x 3.5 mile trips and started perfectly. At 0C, after 5 hours it is dead after a 70mile round trip. Weird!!

Car is 08 AUdI A4
 
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I'd guess your battery is starting to give up the ghost.

I had a similar thing with my truck recently, required a few jump starts after standing overnight and subsequently needed one replacing (trucks have two,24v system) after driving from Stoke to Carlisle (where it failed to start and a dead cell was diagnosed by Scania)
 
Check the battery terminals are tight.
Check that nothing is left on that shouldn't be such as Glove box light/Boot light etc
If none of the above then the Cold is killing your battery & you need a new one.
 
iaind said:
Check the voltage across the battery terminal when it's running, it could be the alternator
Click to expand...

The garage did checks on this and it came out as OK.
Not sure how much they know like as they didn't seem to know much about this model but the car does seem to be charging, it's just draining really quickly
 
There is deff not anything left on - unless the car isn't going into 'sleep' mode like it should.
But it's hard to check. The multimedia system is in the boot and just opening the boot awakens the car from sleep mode so I can't tell if it's on when it shouldn't be.

But I doubt it is that as the problem went away for a week after being on and off for 6-7 days in the cold weather. Now the cold is back it's instantly dead so seems to be pointing towards that.

Just wasn't sure if it could have such an effect. Guess it can if theb attery is already on the way out anyway


Got it booked in now then to get it changed. £130 - damn these massive premium batteries for all this fancy electronic crap I don't use. lol
Mind you - due to Audi wanting you to go back to them it's not a quick change like older cars so i'm happy to just pay. The battery alone was £110 so not much labor on there
 
blitzwing85 said:
The garage did checks on this and it came out as OK.
Not sure how much they know like as they didn't seem to know much about this model but the car does seem to be charging, it's just draining really quickly
Click to expand...

It doesnt really matter what the car is, testing it has been the same for decades

It should be 12V when it's off and ~14.4V when it's charging. If the charging voltage is too high or low then it means there's something wrong with the alternator. If the voltages are right then it's 99% going to be the battery

I'm guessing it's the original battery from when the car was new?
 
iaind said:
It doesnt really matter what the car is, testing it has been the same for decades

It should be 12V when it's off and ~14.4V when it's charging. If the charging voltage is too high or low then it means there's something wrong with the alternator. If the voltages are right then it's 99% going to be the battery

I'm guessing it's the original battery from when the car was new?
Click to expand...

Ah OK I see, didn't know what voltages it should be. I have also checked this myself at it was 12V, then 14.2V while charging.

So it's deff looking to be the battery. And yes as far as I can tell it's the original. Car is 08 plate so just under 5 years old so battery should not have been changed yet.


I priced up batteries myself at £80 and Kwik Fit will order and fit for £130. I've heard it's a bit of an awkward job on my car as the battery is right in the middle so for £50 i'll just let them deal with it. Not worth my time to save £50.
Damn fancy modern cars. When I had the Type-R I changed it out in 5 minutes
 
All you need is a clamp meter which can measure A, this will tell you if there is a power draw when the car is off. One of the terminals will be shaped so you can get a meter around it.
 
PhillyDee said:
All you need is a clamp meter which can measure A, this will tell you if there is a power draw when the car is off. One of the terminals will be shaped so you can get a meter around it.
Click to expand...

Couldn't get hold of a clamp meter when I needed one even though I actually calibrate these at work and a month ago had 12 of them on my desk!!!!!! Typical.

The car has been fine all week after a jump start then driving just 7 miles per day for 8 days never going over 40mph.
Both evenings after i've had the car on the motorways it has drained completely in just 5 hours. However, on both of those evenings the temperature was 6C lower than the 8 days in between.

I was getting worried that it happened after a long journey but then the warning did start to come on for 4-5 days 2 weeks ago and during that week I again only drove 7 miles a day up to 40mph so I think that points everything towards the battery. It'd probably last a few months more in the warm weather but could have plenty cold days left now so i'll just get it out tomorrow.

Then hopefully that's the last of it
 
Think i'm going to have to do these tests now. Car was dead yesterday morning but not today and temperature has been the same both nights.
First night had slight snow/frost but today has not.

However, can't see why snow/frost would affect it as the battery is in the boot, under the carpet etc. But as of now that is the ONLY difference left to when it drains and when it doesn't over the past 2 weeks.
Every night it drained, it snowed. Every night it did not drain, it did not snow.

This may be normal for car batteries but to me it just seems totally weird.


Man I HATE intermittent faults.
 
If you do have an abnormally high draw causing the battery to go flat the easiest means of narrowing down the faulty circuit is to remove one fuse at a time and retest. Bit long-winded but will definitely pinpoint the fault.
 
Looks like I'll have to set some time aside and do this over the weekend then yes.

I'm getting the battery changed today anyway. It's cheap enough so if it turns out not to be that then so what.
Expected really bad weather this weekend so if I get the battery changed, and the faulty comes back I know to spend some time pinpointing it.
If the fault doesn't come back this weekend when the cold and snow hits hard then I know it was likely the battery! (unless it is totally random / intermittent of course) but at least changing the battery eliminates that so I'm not wasting my time looking for a fault for nothing.
 
Hmm. I had the battery changed yesterday and then this morning the MMI system didn't come on and is totally dead. Everything else in the car is working but the screen on that just won't switch on and no sound comes out either so the whole media system is off.

Damn all these fancy systems in cars now. What a pain.
 
Robbie G said:
Did the mmi work ok when you picked it up?
Click to expand...

Yes it worked when I picked it up at 3pm.
It worked when I left work at 5pm
It worked when I took it out from home at 10pm.

Maybe just a fuse when I turned it on this morning but i'm not so sure. I'll check those later. Battery was rated the same as old one but it seems extremely likely to be related to the battery change!
 
Haven't had a chance to check fuses yet but the Sat Nav and Dvd player part in the boot are working fine - it's just the display.

Seems to point towards a fuse rather than actual damage to the unit. If it is and I change it hopefully it was just a freak coincidence otherwise the battery is causing it and then i'm down to taking it in to Audi...bugger
 
Thought i'd post an update.

I performed a parasitic draw test today when I finally got the gear together and there was a draw of 7.5A initially!!!

When I pulled the fuse for the Radio/Sat Nav/MMI this went down to 1.3A

I know 1.3A is still high but I did had the boot open because the battery is in the boot. So due to that being open i'd expect a high reading.


My plan now is to simply leave it with this fuse out and run the car with no music system. If after a week or two the problem has not returned I can get a quote for the repair of this system and go from there.

If it still happens, then I need to do try and perform this test after letting the car go into sleep mode. It will be hard though due to where the battery is.
Only way I can think of is to put the back seats down, get some really long wires, stick the Amp meter to the window and run the leads through the back and into the boot. That way I can close the car, lock it and let it 'go to sleep'

What a pain
 
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