Battery dying [Resolved]

[AYRGUNN]

Hi all, looking for some advice. I work away for two weeks at a time and when I get home my battery is dead. There are no lights left on or anything like that so wondering what could be draining it?.
I have a usb port and reading light installed with 4 down light in the back. Thats all thats extra in the van. Any ideas? Thanks Iain

 

[archersam]

I guess firstoff remove them and see if any difference. Are they on an ignition live or a perm feed?

 

[nigelcro]

Interesting... I am having similar issues with my '22 T6.1. It is going back to BVMS next week some time for them to run some more in-depth tests. The battery charges perfectly well and I leave it at the end of a day's driving at close to 100%, the following morning it is usually down at around the mid 60%.

At the weekend, we went to a show, the battery was at 90+ when we got there, I turned everything off, including interior lights and made sure nothing was plugged in to either the USB or the 12v. 4 hours later, the battery was at 50% with, as I understand it, nothing pulling charge.

I have a cheap battery monitor fitted, so I can see State of Charge easily on an app.

If we resolve the issue, I will let you know.

 

[Sasquatch]

See what the current drain is and do the maths.

 

[nigelcro]

See what the current drain is and do the maths.

I am planning on letting the clever people at BVMS do that next week.

 

[Dellmassive]

Interesting... I am having similar issues with my '22 T6.1. It is going back to BVMS next week some time for them to run some more in-depth tests. The battery charges perfectly well and I leave it at the end of a day's driving at close to 100%, the following morning it is usually down at around the mid 60%.

At the weekend, we went to a show, the battery was at 90+ when we got there, I turned everything off, including interior lights and made sure nothing was plugged in to either the USB or the 12v. 4 hours later, the battery was at 50% with, as I understand it, nothing pulling charge.

I have a cheap battery monitor fitted, so I can see State of Charge easily on an app.

If we resolve the issue, I will let you know.

Where are you getting the 50/60/100% readings from?

Most % volt meters are very bad at guessing the reading.

But a voltage logger like the BM2 will give you a voltage plot over time, so you can see what's happening.


...

Battery Monitoring -- How I Done It --

Battery Monitoring -- How I Done It -- Part #1 Battery monitoring is a very important part of your 12v system . . . . whether its just the vans starter battery or your leisure setup keeping an eye on the power in your battery bank will keep you from breaking down and make sure your weekends...

www.t6forum.com

...

 

[nigelcro]

But a voltage logger like the BM2 will give you a voltage plot over time, so you can see what's happening.

I got myself one of those. On my Skodas I could get a SoC from the driving data, doesn't seem that VW bought into that particular part of the software - unless anyone knows different???

 

[roadtripper]

It really doesn't take much current draw to drop a starter battery in 2 weeks.

If the battery is 70Ah and you have start stop so it will be around 80% giving you 56Ah. Say 60Ah to be generous and assume the danger level is 50% at 35Ah

That's 25Ah difference. In 2 weeks there are 14 x 24 = 336 hours so you are looking at a 0.075A average drain, or 75mA

Estimating the ECU drain at around 40mA (as the fault.code will.log at greater than 50mA usually) that means you are looking for a 35mA drain.

And that's well within the range of the parasitic load of a USB socket voltage converter - all USB sockets are active devices and will continue to have loads even with nothing plugged in, best to have them on a switch if you regularly leave the van.

2 weeks is quite a long time even with stock electronics, ideally look to see if you can have it on a NoCo/CTEK/Victron maintenance charger.

 

[ginkster]

If you have a leisure battery you can use something like an Ablemail AMT12-2 to keep the starter battery topped up from the leisure battery. Even better if you have solar as it then becomes an everlasting supply.

 

[nigelcro]

Just to sign this off from my end...

BMVS had the van for a couple of days and tested the battery, on and off the van. They confirmed what I was seeing, without any drain on the battery it was dropping from 100% (ish) to 70% (ish) overnight. They called out VW roadside assistance, as the van is still under warranty, the technician ran his tests and confirmed that the battery wasn't very good, but it wasn't bad enough to be replaced under the VW Warranty!

The nice people at BVMS replaced the battery for me at no cost.

I have been monitoring the battery for a week and behaviour is much as it should be, so I don't think I have any rogue current draws going on, but I will continue to monitor it through my BM2 thingy.

Thanks to BVMS for their excellent service!!

 

[AYRGUNN]

Just to sign this off from my end...

BMVS had the van for a couple of days and tested the battery, on and off the van. They confirmed what I was seeing, without any drain on the battery it was dropping from 100% (ish) to 70% (ish) overnight. They called out VW roadside assistance, as the van is still under warranty, the technician ran his tests and confirmed that the battery wasn't very good, but it wasn't bad enough to be replaced under the VW Warranty!

The nice people at BVMS replaced the battery for me at no cost.

I have been monitoring the battery for a week and behaviour is much as it should be, so I don't think I have any rogue current draws going on, but I will continue to monitor it through my BM2 thingy.

Thanks to BVMS for their excellent service!!

Dropping almost 1/3 of power in a few hrs is crazy. Imagine frosty nights and mornings. Did the battery loose as much power when not under load at the same rate?

 

[nigelcro]

Dropping almost 1/3 of power in a few hrs is crazy. Imagine frosty nights and mornings. Did the battery loose as much power when not under load at the same rate?

I don't have the full tabulated results, but broadly speaking, the battery dropped lower when connected to the van. On the van it was dropping from 100% (ish) to 60% (ish) overnight, and IIRC, off the van it was only going down to about 70%. There is always going to be a small draw when the battery is on the van, if nothing else the battery monitor was pulling a few milliamps.