Cupra 2016 - battery drain hard to find....

ymalool

Active Member
Feb 9, 2017
8
0
Long story short, Its been almost 6 months now that I am chasing a very illusive power drain.
Leaving the car locked for more then 2-3 days will result in a "low battery" message and hard start till recharge while driving is done and then again ....

Did 2 tests already - one with a voltmeter connected to the (-) terminal and observed that once car is locked , the voltage consumption is going within 1-2 minutes from 4.1 Amps to 0.025 amps - which to my understanding - is good.

Going over the fuse boxes while car is locked, seems that none of the fuses is drawing any current - not all fuses can be checked tough - some are "closed" type.

Replaced 2 new batteries already - same behavior
Disconnected any aftermarket installation I had - recording camera + radar detector - same behavior

Any suggestions , trying all you gr8 guys here before trying to go to the dealership .
 

cupra14

Active Member
Aug 31, 2017
332
63
England
25mA should not flatten a battery in that time so either the battery is unwell (e.g. was left discharged such that it lost capacity, or is the wrong type) or it goes above 25mA (or I suppose a faulty meter but that is not too likely).

You can get a bit more information by checking the battery voltage at its terminals - should be above 12.6 really after not being used overnight and then hardly fall day by day (in your case, you'd better check more often!).

(By way of example, my car has a 6 yr old battery which was only 12.55V and after another few days is now 12.52.)

Oh - may be wise to post detailed battery info (make, kind, capacity, etc)

Some meters can record the max current which would make checking if it goes above 25mA easier.

I think you mean you've also been checking the voltage drop across fuses (which would be small mV) but if the current is genuinely 25mA even over a long period it's hardly anything anyway.
 

ymalool

Active Member
Feb 9, 2017
8
0
25mA should not flatten a battery in that time so either the battery is unwell (e.g. was left discharged such that it lost capacity, or is the wrong type) or it goes above 25mA (or I suppose a faulty meter but that is not too likely).

You can get a bit more information by checking the battery voltage at its terminals - should be above 12.6 really after not being used overnight and then hardly fall day by day (in your case, you'd better check more often!).

Oh - may be wise to post detailed battery info.

Some meters can record the max current which would make checking if it goes above 25mA easier.

I think you mean you've also been checking the voltage drop across fuses (which would be small mV) but if the current is genuinely 25mA even over a long period it's hardly anything anyway.

The battery is from the exact spec of the manufacturer and was replaced twice already.
It does fall under 12.3 over a period of 2 days when the car untouched- hence the battery drain.

The test I've performed with the (-) line connected in parallel to my voltmeter was done over a time period of 10 minutes - its always possible that something happens after that time period...

Are there any known issues in Cupra around this issue?
 

Adrian300

Active Member
Jun 10, 2019
259
113
We used to start disconnecting things to test what is causing the drain. This of course once we had established a drain was present.

Sent from my GM1913 using Tapatalk
 

martin j.

Active Member
Feb 11, 2007
1,996
889
Fife
Drain through faulty alternator? I have in the past pulled all the fuses replacing one at a time until the drain re appeared.
 

cupra14

Active Member
Aug 31, 2017
332
63
England
The battery is from the exact spec of the manufacturer and was replaced twice already.
It does fall under 12.3 over a period of 2 days when the car untouched- hence the battery drain.

The test I've performed with the (-) line connected in parallel to my voltmeter was done over a time period of 10 minutes - its always possible that something happens after that time period...

Are there any known issues in Cupra around this issue?

There are multiple kinds of battery which may be fitted so how about posting _details_ rather than no details.

10 mins is very brief and you'd be incredibly lucky to find a drain in that time.
 

RUM4MO

Active Member
Jun 4, 2008
7,784
983
South Scotland
The "power management" system shuts not required systems down quite quickly after engine stop, so if 25milli amps is being noted after 10 minutes then that seems okay to me. What is happening after that is important and trickier to check over a longer period in time, ideally the minimum you would need to do is to stuff a very low value precision high wattage resistor inline with the battery lead +ve or -ve and log the voltage drop wrt time over a 24 or 48 hour period, then after finding that there was indeed a random higher current being drawn, then you would need to split up the wiring system to narrow down which area was causing this problem, then drill down deeper.
I'd doubt of any main dealer would bother taking that approach!
What I had on a late 2009 Ibiza was a similar situation, I exhausted all my ideas on splitting wiring areas and locating which one was causing the issue, so I handed it into my local SEAT dealership with the "I think that it might just be the BCM software issue that early 6J Ibiza were known to have" - they would not have any of that "that is just an internet myth we need to work on facts" - so first attempt of overnight testing/monitoring found nothing - no faults present and no current drain, I told them to keep it longer, next day or day "we found a fault, the steering angle sensor under the steering wheel - (only used on that car to switch on the individual fog light), and we have replaced that and now there are no faults £380 please, so I paid up but also added "why can that affect the car with the ignition off and so the engine not running?" - "oh,that would generate noise in the CAN lines and keep wakening up other systems and so drain the battery" - I said that I did not think that was correct - but they are the experts! A month later with me constantly monitoring the battery using a remote lead and never driving the car, I could see that it was still a problem, so back to that dealership, a quick "absolutely no faults and no battery draining was declared after another few days of testing/monitoring!" - so I took it away and started looking further into this and coming up with absolutely no answers other than it must be due to the wrongly programmed BCM which now needed recoding/programming - then I got a letter to say that SEAT garage was closed and so I should head for another SEAT dealership and SEAT UK would support me! Bother!

So, as that car's owner, my daughter was coming home for Christmas while still working abroad, I booked it into this next SEAT dealership, when I mentioned all what had happened and my thoughts about it being a BCM S/W issue, the service receptionist took this onboard and noted it down as they had this exact issue with a 2009 VW Polo that they had sold and it was a BCM S/W issue which was resolved by requesting a solution from VW. I handed that car in a few days later just before Christmas and they found no faults so took the next step which was to request a solution from SEAT via a technical request, an answer came back from SEAT directing them to a S/W patch, and so when that daughter left UK after Christmas I booked that car in for that patch to be downloaded into that car - problem solved, it only took me a couple of years almost!

Now I 'm just repeating that tale to indicate that some times these problems are difficult to resolve, so your first step really does need to be to get that car's systems checked for faults, if none found a dealer should move on to monitoring the drain over a longer period - over night or nights and then moving on from there in a SEAT directed manner - horrible situation to be in, hopefully SEAT can find the root cause quickly.
 
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ymalool

Active Member
Feb 9, 2017
8
0
Short update, i have set in the car and locked it. After about 1-2 minutes, a click sound was heard and a hiss sound started from the twitters area. I have switched the radio on, right before the screen came on, the hiss stopped and the radio kicked in. Turning off the radio again, same behavior- no hiss, relay sound and a hiss sound from the twitters.
Pulled off the radio fuse, no radio, no hiss sound.
Will check the battery current tomorrow and update.
 

ymalool

Active Member
Feb 9, 2017
8
0
Ok, another short update and a pic of the battery installed.

so i did the amp draw test with and without the radio fuse and the results are interesting.

with the fuse on, im getting 0.95A while when its out , well - its only 0.03A as seen in the pic.

so, diagnostic sorted?
F47F0ED4-6442-44D2-A64C-3B4CC730CA86.jpeg
 

Walone

Active Member
Feb 10, 2016
1,533
418
Near Heathrow
Ok, another short update and a pic of the battery installed.

so i did the amp draw test with and without the radio fuse and the results are interesting.

with the fuse on, im getting 0.95A while when its out , well - its only 0.03A as seen in the pic.

so, diagnostic sorted? View attachment 13998
Do you have an 'after market' radio fitted? I seem to remember something about some non-factory fitted radios causing high current drain.
 

ymalool

Active Member
Feb 9, 2017
8
0
Do you have an 'after market' radio fitted? I seem to remember something about some non-factory fitted radios causing high current drain.
Well sort off an aftermarket.... its the original radio with screen BUT it has been locally installed with an aftermarket navi option- and that may be the issue.
 

Marko70

Active Member
Jul 6, 2019
107
44
Well sort off an aftermarket.... its the original radio with screen BUT it has been locally installed with an aftermarket navi option- and that may be the issue.

anything non standard would of been the 1st thing to check? glad you got it sorted in end ☺
 

Chrispy

Active Member
Oct 6, 2018
129
42
The test I've performed with the (-) line connected in parallel to my voltmeter was done over a time period of 10 minutes - its always possible that something happens after that time period...

Do you mean in series? You can't measure the current in parallel.
 
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