Hi all,

I’m dealing with a curious issue after attempting to update the Amundsen firmware in my Superb.

A few days ago, I started the update and left it running overnight in the garage, with the key in the ignition (half-turned, as required) and the car connected to a smart charger. Unfortunately, the next morning the battery was nearly dead, I suspect the charger simply didn’t have enough capacity to keep everything alive for so many hours (lesson learned: I should have checked back sooner).

I let the battery charge for a while, but since I had to drive that day I tried starting the car. It struggled badly but eventually fired up. For the first 10 minutes everything seemed normal, until I got the red battery warning (“not charging”). I turned around, drove home, and left the battery on charge overnight to recover fully. At that point I thought the problem was just from having started the car with such a low state of charge.

The next day, with a fully charged battery, I had to do about an hour’s worth of city driving. Almost immediately after starting, the red battery warning appeared again. I drove anyway (urgent errand) and had no functional issues during the trip. The only odd thing was that idle RPM stayed high, about 1050 vs. the usual 800. My guess is that the car was trying to push extra charging current, since a fault code was stored.

My question:

How likely is it that this warning is simply a result of starting the car with a very low battery, and that it’s just a “sticky” error that remains until cleared? In other words, could the charging system itself be working fine, but the ECU is still flagging the error until it’s reset?

How did you connect the charger? If it was to both battery terminals the car won't have been able to monitor the fact that the battery was being charged so may still think it's flat

5 minutes ago, skomaz said:

How did you connect the charger? If it was to both battery terminals the car won't have been able to monitor the fact that the battery was being charged so may still think it's flat

Connected it as usual, red to positive, black to earth and then plugged in to the wall. Removed the other way around, done this tens of times, with no issues.

Was your 'black to earth' to a an earthing point on the chassis of the car or on the battery terminal? - if on the battery terminal the battery monitoring connection is bypassed and hence the car doesn't know it's being charged.

Doing the former may not matter too much for a quick top-up of a slightly depleted battery but probably would for a very flat battery.

Edited 26 August, 202526 Aug by skomaz

It was on the chasis of the car. I went out and bought a multimeter, unfortunately this seems to be a bigger issues indeed and the car is right about battery not being charged. The battery is at 11.65V with engine turned on. I will go ahead and check the fusible link for the generator, I suspect it might have blown while starting the car when the battery was almost empty.