Parasitic battery drain -CCCU issue?

[Pinkythelabrat]

Good afternoon,

I’ve been having issues with my battery going flat in my 2002 TDi75 for a couple of years now. I think I’m at the point of trying a new CCCU unit to see if that helps but I’m hoping for some advice first.

The battery will drop from completely charged (with a charger) to 12v overnight and it’ll be 11.6v in two days and down and down. I hooked up a solar panel and charge controller through the cigarette lighter so it’s charged to 14.4v daily in summer but it’s still only 12.3v shortly after the sun goes down and 12v the next morning.

I replaced the battery with an F11 last year thinking the battery was damaged. It was from Varta.

I used VCDS lite and all my doors are locking and safe-ing properly (although one has an intermittent ‘won’t desafe’). My alarm unit has recently decided to die and the car no longer ‘chirps’ on locking but that’s only been the last couple of weeks and the issue precedes that.

My CCCU is 8Z0 959 433 Q - which I now suspect isn’t one of the more reliable.

I live on a main road so leaving the car unlocked until everything shuts down is a bit of a challenge but I’ve used a voltmeter and looked for strange voltage drop across the fuses with no luck - nothing obvious. I was hesitant to start yanking fuses but are there certain fuses to start with a meter inline? Perhaps CCCU?

Thanks for any advice and if anyone happens to have a CCCU for sale with a couple of keys I might try a swap to see what happens.

Alex.


Sent from my iPhone using Tapatalk

 

[Sidewinder]

If you have a digital voltmeter, set it to read dc amps and put it in series with the battery negative lead, sit it up on the side boot shelf next to the window and close the doors (no need to lock) wait 2 minutes and see what the car is drawing at rest, any more than about 50mA (0.050A) and you have a problem, I had 180mA constant drain and it was the alarm unit in the boot, fuse 36, found by pulling a few fuses at a time, closing the doors waiting the 2 mins and checking the meter. Don’t be afraid of pulling fuses, make sure you have the stereo code and you may have to re pair the remotes but that should be about it.
Good luck.

Andy

 

[audifan]

As you are already experiencing an alarm problem @Sidewinder has effectively pointed you in the direction to at very least try first. The alarm fuse 36. Removing it altogether would do no harm until the alarm unit is replaced.

 

[Pinkythelabrat]

Yup yup thank you. I’ll give that one a solid try first.

I’m sure my constant drain was over 50 when I checked last time…

Cheers fellas.


Sent from my iPhone using Tapatalk

 

[Pinkythelabrat]

Good morning.

My cool new UNI-T loop dc meter (birthday gift) doesn’t seem to want to work! I’m probably using it wrong. Anyway, old meter in series it is…


using the 10a it ‘looks’ like a 300mA draw but when I’ve connected the eads for fine reading it’s settling on 33.4mA or so… at least I think that’s what I’m reading…

So maybe I don’t have a parasitic draw after all? Or maybe something is trying to turn on more than 2-3mins after I lock the car?

Incidentally, having the thin wires in series with the battery seems to not allow enough juice for central unlocking on the fine range so need to be careful with locking up.

Why is my battery flattening?!? It was 12.7v last night at 11pm and 12.3v this morning at 8am… with a solar panel.

 

[Guest 4123]

How many watts for your solar panel, Alex? Under glass, you will lose about 60% of the output, even more at the rear of the car. A 20w panel should be sufficient for all-year round use but only if placed at the front and assuming you have nothing draining the battery more than it should.

RAB

 

[Sidewinder]

I think you could have a problem with your measurements, the 310mA reading on the 10A scale looks realistic, you may have damaged the 200ma max range by pulling 310ma plus the central locking current through it, it should be fused though on the 200ma range.
A correctly operating meter would read the same on both ranges.

Andy

 

[Guest 4123]

The most convenient way of measuring current is with a clamp meter. No need to disconnect anything and no risk of damaging anything. You need one that can measure down to a few mA.

RAB

 

[Pinkythelabrat]

Thanks everyone.

I got myself a nice clamp meter for my birthday but it wasn’t giving me consistent readings… that’s the ‘loop’ meter I meant. I think though that it’s been my other meter perhaps being on the fritz…

The 200mA range on my yellow meter IS fused - it’s been blown up before… but selecting 10A is giving odd readings rather than just moving the measure so I think it’s unreliable.

With my DC clamp meter on its settling to 0.19 Amps of draw with the car locked up. That would flatten a battery! 33.6Ah of discharge in a week - so about 50% of the charge in my 85Ah F18 - so DEAD!

Pulling fuse ‘36’ - listed in the panel as ‘ ‘ - didn’t change it noticeably. Still 0.182-0.19A

My meter then powered off so I restarted it and set it up again. Now it’s showing only 0.3A for a couple of minutes then 0.03-0.07A of draw (it moves around a bit) with the car locked up!

I’m wondering if something is sometimes turning off and sometimes not.?

The interior light (front) appears to add 1.3amps to the circuit. No wonder leaving that on flattens your battery!

Incidentally my solar panel set up is allegedly 40 watts - it’s about a half square meter of semi flexible panel and it’s run into the battery via a lead-acid charge controller. It’s currently apparently pushing 4 watts into the battery (although I disconnected it for testing) Papering over the cracks…


Sent from my iPhone using Tapatalk

 

[Guest 4123]

To make the most of your solar panel, place over the dashboard. In the rear of the car it will be at least partially shaded, which will kill the output.

RAB

 

[PlasticMac]

As you are already experiencing an alarm problem @Sidewinder has effectively pointed you in the direction to at very least try first. The alarm fuse 36. Removing it altogether would do no harm until the alarm unit is replaced.

I wonder if the alarm sounder is on the same fuse as the alarm circuit? If not, pulling fuse 36 doesn't rule out the sounder, which we're pretty sure is duff.
Pain to get too, I know, but unplugging the sounder is the only way to check if it's the problem.
Mac.

 

[Pinkythelabrat]

Afternoon,

Sounder pulled and respect for Audi’s plastic origami increased (respect does not equal like-for however).

The batteries are definitely toast but have only leaked very minimally - despite having pretty much no remaining voltage.

I suspect the main issue is that a component has popped and taken a chunk of the PCB traces out as well. Irreparable without a comparable board to work from and rebuild. I assume it’s on the 12v supply end - perhaps it overheated from trying to charge dead batteries. Who knows?

Anyway - a replace alarm sounder is needed. I’ll add a Wanted ad. Maybe this will reduce the drain but it seems unlikely since I doubt any power was going through this.

Sent from my iPhone using Tapatalk

 

[PlasticMac]

Afternoon,

Sounder pulled and respect for Audi’s plastic origami increased (respect does not equal like-for however).

The batteries are definitely toast but have only leaked very minimally - despite having pretty much no remaining voltage.

I suspect the main issue is that a component has popped and taken a chunk of the PCB traces out as well. Irreparable without a comparable board to work from and rebuild. I assume it’s on the 12v supply end - perhaps it overheated from trying to charge dead batteries. Who knows?

Anyway - a replace alarm sounder is needed. I’ll add a Wanted ad. Maybe this will reduce the drain but it seems unlikely since I doubt any power was going through this.

Sent from my iPhone using Tapatalk

Same sounder used on TT Mk1, A4 etc.
Lots on the bay.
Search by part number. Only look at ones that end in A.
Edit: Early ones used nicads, later are nimh.
Mac.