Battery drain or dodgy battery?

[Scotti8]

Hello hope you are all well.
I have a 2021 T6.1. Every now and again in the morning it would struggle turning over, but would always start. When this happened the dash always showed "VCC error", along with some other errors (I cant recall right now, but I think it said the senser that the adaptive cruise control and the auto-brake/anti-collision uses).
After taking it into VW twice they said the battery was fine and they couldn't replicate the issue (which they wouldnt as it along happened after sitting over night).

I went away for 3 weeks last month and on returning the van struggled again, but did start. Went to work for 8 hours, and when trying to start the van after work it was completely flat.
I borrowed a Noco boost, to start it, but next morning the same thing, completely flat. I borrowed smart charger (unsure of the brand) and charged it for 6 hours at work. The amp draw from the charger slowly went from 6amps to 2amps in the 6 hours, so I assumed it had charged at least 50%. The next morning it was completely flat again. So I charged it for another 6 hours. It was fine for 3 days, and started no problem.

Between home and work is 2 miles. But I also drive shorter trips to the shops and longer 20 mile trips 2 or 3 times a week.

After 3 days it suddenly refused to start again.

I then borrowed a Noco charger and started to charge it at work, and it showed the battery at 1 of 4 bars (so flat). Within seconds it went to 2 of 4, the 3 of 4, then started flashing green, indicating it was fully charged! (well, it indicates that the battery is near enough full, and the charger is "optimising" the battery)

Its a self-conversion. However the only two connection points are directly from the van battery to a CTEK then a leisure battery, and the second point is into a spare fuse for ignition live. I removed both of these for a week to make sure it wasnt either of them, but the issue continued.

So the question is:
is it most likely a faulty battery: should I splash out on a new battery (£300+ including fitting) Or
is it most likely a parasitic drain somewhere: should I spend £100 per hour to investigate?

Any help or advice would be most welcome! Thanks

 

[nigelcro]

I had a similar issue with my T6.1.

My first step was to install a cheap battery monitor - one of these -

https://www.amazon.co.uk/Battery-Monitor-Campervans-Compatible-bluetooth/dp/B08VHMJYXY

Then once I had a few weeks data I went back to the people I bought the van from, they ran some tests and we all agreed that the battery was sh*gged. They tried to get VW to replace the battery under warranty, but the VW Tech said the battery wasn't bad enough. The vendor then replaced the battery for me, free of charge, and I have had no problems since. I still check the Battery Monitor every day though!

We couldn't find any parasitic drain anywhere, I was swapping fuses out whilst I was running the monitor to make sure that nothing was pulling power unexpectedly. The management systems, and the battery monitor of course, will pull small amounts of power, but I was dropping from 95% to 60% overnight.

HTH?

 

[whodat]

What is the voltage showing?
Get yourself a multitester or a cigarette lighter tester so can just plug it in when in driver's seat without getting hands mildly dirty.
Then, what is voltage showing when driving or at least engine running?

If you have a Carista or similar, you'll be able to see the 'drain' as the computer sees it.

 

[Scotti8]

I had a similar issue with my T6.1.

My first step was to install a cheap battery monitor - one of these -

https://www.amazon.co.uk/Battery-Monitor-Campervans-Compatible-bluetooth/dp/B08VHMJYXY

Then once I had a few weeks data I went back to the people I bought the van from, they ran some tests and we all agreed that the battery was sh*gged. They tried to get VW to replace the battery under warranty, but the VW Tech said the battery wasn't bad enough. The vendor then replaced the battery for me, free of charge, and I have had no problems since. I still check the Battery Monitor every day though!

We couldn't find any parasitic drain anywhere, I was swapping fuses out whilst I was running the monitor to make sure that nothing was pulling power unexpectedly. The management systems, and the battery monitor of course, will pull small amounts of power, but I was dropping from 95% to 60% overnight.

HTH?

Thanks, Ill have a look at that battery monitor. Id thought of the USB ones, but you have to be inside the van so thought it wouldnt show an accurate reading. That bluetooth one looks good tho

 

[Scotti8]

What is the voltage showing?
Get yourself a multitester or a cigarette lighter tester so can just plug it in when in driver's seat without getting hands mildly dirty.
Then, what is voltage showing when driving or at least engine running?

If you have a Carista or similar, you'll be able to see the 'drain' as the computer sees it.

On the multimeter it is showing 12.7 - 12.8 volts.
It drops to around 12.4 v quite fast (within a few hours), but then stays around 12.2 - 12.3 v for ages. When it wont start its reading 12.2 / 12.3 v

I have a Carista but didnt know you could see drain using it, ill look into that.

 

[ginkster]

On the multimeter it is showing 12.7 - 12.8 volts.
It drops to around 12.4 v quite fast (within a few hours), but then stays around 12.2 - 12.3 v for ages. When it wont start its reading 12.2 / 12.3 v

I have a Carista but didnt know you could see drain using it, ill look into that.

That sounds like normal behaviour, except it not starting. Anything over 12v is fine (a healthy system shouldn’t drop this low inside 2-3 weeks) and the van should start easily. The drop after a few hours is normal.

 

[Scotti8]

So I connected the carista. Had to switch on the ignition (but engine not on, and open the bonnet open).
It showed 64% battery, and 10amp draw. Is 10amps normal? Seems high. It quickly dropped to 62% then 60% within seconds, but this could just be an inaccurate reading because the battery is in use? (The multimeter showed 12.17v)
I switched the ignition off, and the draw dropped to 4 amps. 20 seconds later it went to 0 amps. Opening the drivers door, it went to 2 amps.

There was just this one fault code 66052 "vehicle communication bus e performance", which I cant seem to find any info about.