Quick Quesion RE 2017 V90 Support Battery

[wynnj]

Originally Posted by RSK55

The function deemed least important is full p/s, so that is the first thing that gets reduced when the battery is struggling.

Or more likely because it's the highest power drain.

[Chudy85]

Originally Posted by mannyo1221

So, I thought I would update this thread.

After charging the batteries to full, all was well for a few weeks as we had that milder air over the UK so temperatures where not that cold.

Roll onto last week, we have had several cold nights and the issue is now back, except I now have the "service support battery" message. Car appears unaffected, except no stop/start which is expected behaviour

So in the coming weeks I will replace the support battery to finally resolve this.

Car is just past 7 years old, and been with me for 3 years so unsure if battery previously replaced. it had 28K miles when I got it, now on 57K.

Exactly today I have got the same issue like you. Few weeks ago I had information on dash that Start/stop support battery service required I have charged both battery thro charging point under the bonnet and all was good until today!
Support battery is dead 10.2V only.
Even if I am driving or charging by the charger there is still only 10.2-10.5V. Even charger wont won't wake up this battery.

I think only new battery is needed.

[Chudy85]

Do you know if that will be enough to just unscrew 2 bolts and simply replace with a new one?

Will it be enough just to delete this DTC by diagnostic tool from CEM and the issue will disappear or need to drive for a longer distance?
I saw the YT video that you can disconnect 2 sockets under the bonnet and negative connector from the main battery. But it will reset the main battery too and the car will think I have replaced both of them.

Any advice?

[lazydog]

Hi , just a quick question I have parking brake issues , ive checked my start stop battery and I am getting 13.5v on the battery terminal and 12.5 on the post under the red cap, I'm taking this is normal for the original battery on a 2017 v90cc.
thanks