12 Volt System Not Charging. Stop Driving Now.

[BigJakk]

Hello Folks,

 

Tearing my hair out with this one now with my Mk3 TDI VRS...

 

On the motorway the other week, out of the blue dashboard warning popped up "12 Volt System Not Charging. Stop Driving Now" very rapidly thereafter lost power steering and as i got onto the hard shoulder pretty much everything on the dash lit up (lack of power to the systems I imagine) and then engine power went. Spent six hours on the shoulder waiting for recovery, hazards managed to keep going for about 5 hours which made me think its probably not a battery issue but more that the battery isn't charging. When recovery arrived we checked the Aux belt (which is less than 12 months old), which was still intact and was spinning. With a boost pack we were able to get enough power to drive the car onto the flatbed and then back off at the other end.

 

RAC home start came out the following day, had a look over and suggested it was an alternator/charging issue. 45 minutes on charge from his van and the car made it under its own steam to my mates garage a few miles away.

As everything seemed to point to a charging issue and therefore the alternator he changed that and also fitted a new battery as a "might as well do" as I've no idea of age of the existing battery and I've had the car for three years myself now.

 

I've had the car back two days in which I've covered about 80 miles. Yesterday on the way home from work I noticed that the Stop/Start wasn't kicking in and the dashcam which is piggybacked to a switched live fuse behind the glovebox was randomly turning itself on and off. About a mile from home the same  "12 Volt System Not Charging. Stop Driving Now" message pinged up. Fortunately there was enough life in it to make it home.

 

Having checked the battery today with a multimeter its only putting out 11.98v with the ignition off. With the engine on this dropped to 11.58v, so the battery clearly isn't getting any charge to it.

 

Just wondered if anyone might have any experience of this or any starters for ten as to where I start looking next.

 

Cheers guys

[Breezy_Pete]

There are some high-current fuses at the front of the under-bonnet fusebox, with heavy cables bolted to them.

No. 2, the second one from the left as you look at them connects alternator output wire to battery positive.

Check that with engine off you can measure the same voltage on the wire going to that fuse, as there is at battery positive.

It's a huge (400Amp) rated fuse, but if that had cracked or something, it would mean the alternator could not get any charge to the battery.

[NikTheGeek]

What a coincidence. I had the same this week. Got a warranty but Skoda weren't interested in even looking at it for 2 weeks as they were so busy. I swapped batteries first (no issue as it was on the original still anyway) and when that didn't fix it, I dropped it off at a local independent who diagnosed a failed alternator and replaced it. Had it back 2 days and so far so good. But thanks for the tip about the fuses and cables under the bonnet if it does come back.

 

 

Edited 16 April, 2023 by NikTheGeek

[BigJakk]

Spent a few hours under the bonnet today,

 

Battery was showing 11.5v and when started this dropped lower, suggesting that the battery is powering everything with no charge being passed through from the alternator.

 

Hooked up a Foxwell OBDII scanner to the car and did some live data on the battery voltage which confirmed the above. Also logged some of the "Generator" (read Alternator) data. With the ignition turned on it initially read as zero for a few seconds before jumping up to 308,000+ Watts at 30% utilisation which clearly isn't right.

 

Located the main busbar style fuse/relay that you referred to Pete. With the engine off this was also giving 11.5v as per the battery level. Ended up taking it out and checked it with the multi-meter, putting one lead on the main metal bar and then the other on each of the terminals of the fuse (125A/400A/B+/80A/80A/50A) and each one showed good continuity, so im afraid its not that (which is a shame as it looks a fairly straight forward and cheap thing to swap).

 

The alternator is clearly brand spanking new and shiny and the belt is intact and seems to have decent tension on it. I couldn't really get to the alternator itself as its buried stupidly deep and out the way (the fact there are coolant lines running right over the top of it seems a bit of a silly design idea too!) to check connections. There is only one connection visible/accessible  at the top right side of the alternator, which seems to be properly connected, however this looks to be of too thin a thin gauge to be one of the main electrical connections.

 

The battery eventually died and is on a trickle charger now to try and get some life back into to it.

 

Edited 16 April, 2023 by BigJakk

[Breezy_Pete]

21 hours ago, BigJakk said:

my mates garage

I think it has to go back here, doesn't it. Must be some kind of warranty on the parts and labour. Job clearly not 100%.

 

[BigJakk]

Just as an addendum, checked the battery registration with the OBD2 scanner as well and it looks like this hasn't been updated to the new battery, as its still showing a 68Ah where the new battery is 70Ah. Tried to amend it but the Foxwell couldnt make the adaptation for some reason. I cant see that being the issue though as there is no charging of the battery happening at all, wheras if the battery registration was the issue i would expect it to still be charging, but just under/over charging.

 

Just for future reference for anyone wanting to know where the main fuse bar is, I've attached a couple of images. Its a combination of 10mm and 8mm sockets required to undo the captive nuts (one is a bolt) and its a good idea to note which cable leads to which terminal as though they are labelled, some of them are duplicated (there are two "K" cables, one red and one black).

 

Cheers

[Breezy_Pete]

Can you see enough of the back end of the alternator to be sure they reconnected the other end of that cable to it? 

Properly dangerous if it's just floating about loose down there!

 

Edited 16 April, 2023 by Breezy_Pete

[BigJakk]

31 minutes ago, Breezy_Pete said:

Can you see enough of the back end of the alternator to be sure they reconnected the other end of that cable to it? 

Properly dangerous if it's just floating about loose down there!

 

Hello Pete,

 

From what I can see online and elsewhere there looks to be only one connection to the alternator (the attached image isn't from mine, its from a youtube video) which is to the right side of the alternator as you look on the engine bay, within the plastic section (im guessing that's the voltage regulator). Fortunately I can confirm that's connected.

[Breezy_Pete]

Yep, that's good, assumingyou mean where his fingers are?

 The plastic two-way connector also needs to be connected, but I think you said above that this is also true.

Edited 16 April, 2023 by Breezy_Pete

[BigJakk]

38 minutes ago, Breezy_Pete said:

Yep, that's good, assumingyou mean where his fingers are?

 The plastic two-way connector also needs to be connected, but I think you said above that this is also true.

 

The plastic two way connector is definitely plugged in.

 

Purely coincidental that I happened to take a screen grab just as his hand was on the threaded connector without realising the significance of what it was....

 

From the top of the engine bay i cant make out at all whether that is or isn't connected up - might have to get underneath it tomorrow and have a look. 

 

Cheers for the help Pete

Edited 16 April, 2023 by BigJakk

[BigJakk]

Just by way of an update;

 

Dropped it back at the garage today, turns out when the battery replacement was done the ODBII tool they had on hand wouldn't let them update the ECU with the new battery info (interestingly, when looking at it over the weekend I had been able to check the battery registration with my OBD2 reader and had seen that it was still set to the old battery, however my tool also refused to update the battery info). They tried an alternative OBD2 tool today and that allowed them to delete the old battery info and write the new battery.

 

Touch wood, fingers crossed etc. that seems to have fixed the issue. I picked it up this afternoon and upon returning home put the multi meter across the battery which was showing 12.6v at idle. With the engine started and some of the electrical systems turned on this jumped up to 14.5v, so the battery seems to be getting charge from the alternator (when testing it beforehand over the weekend all that was happening when a load was put on the battery was that the voltage was dropping, suggesting to me that the battery was doing it all on its own).

 

I'll keep an eye on it over the next few days and report back if there are any more issues.

 

Cheers