Battery and collision avoidance

[Hadajag]

Hello
On Wednesday I was involved in a low speed shunt. The collision avoidance system did not activate. If it had I would have probably not sustained any damage
This was towards the end of a 100 mile journey
At around 40 miles I got a warning that the park assist was disabled "service required"
Subsequently reading the on screen manual it becomes obvious that if park assist is not functioning then all proximity detection including collision avoidance is disabled
I phoned my Volvo dealership and was told that the malfunction was probably due to.a low 12V battery charge due to the car not being used for a few days or only on short journeys. When I said that I had already done 40 miles when I got the warning they said that was not enough to charge the battery!
The proximity sensors were definitely working as I manoeuvred off my drive
This whole battery charge thing is becoming unbelievable as highlighted in other threads.
Before discussing it is important to.distinguish between MHEV cars and PHEV cars and previous models.
The thing that gets me is that the alternators fitted to modern cars are at least 70 amps and whilst perhaps only half that is available to charge the 12V battery. An hours drive should give the battery a very substantial charge. I have 3 other cars including 2 classics all of which start after sometimes standing for weeks.
What do others find?

[Lexman8]

On my XC90 the ultrasonic sensors feed only the park assist system and the proximity display on the centre screen. They do not input to any of the collision avoidance systems. These use the front Intellisafe camera and radar and, if fitted, the BLIS radars at the rear.

So depending upon the type of shunt it's perfectly possible that collision avoidance wouldn't intervene.

if park assist is not functioning then all proximity detection including collision avoidance is disabled

Your car may be different but I'd be surprised if the ultrasonic sensors input to collision avoidance as their range is very limited and therefore would only be useful at very low speeds where, in fact, collision avoidance is disabled by design.

[Hadajag]

Whilst it is not 100% plain in the manual it is definitely implied that if park assist is not working then collision avoidance will not function.
Yes this was a very low speed collision however collision avoidance regularly puts the brakes hard on and sounds the alarm when I am turning on my drive both in forward and reverse motion. Dont know if they have changed functionality in the intervening 5 years between manufacture of your car and mine?

[SmartMAC]

Originally Posted by Hadajag

Whilst it is not 100% plain in the manual it is definitely implied that if park assist is not working then collision avoidance will not function.
Yes this was a very low speed collision however collision avoidance regularly puts the brakes hard on and sounds the alarm when I am turning on my drive both in forward and reverse motion. Dont know if they have changed functionality in the intervening 5 years between manufacture of your car and mine?

My 12v battery went faulty and I had the same issue with none of the safety systems working as they should.

[Lexman8]

Originally Posted by Hadajag

collision avoidance regularly puts the brakes hard on and sounds the alarm when I am turning on my drive both in forward and reverse motion.

Is it definitely the full-on collision alarm (dab on the brakes, alarm and head-up display) rather than an auto brake plus distance warning?

Dont know if they have changed functionality in the intervening 5 years between manufacture of your car and mine?

Your car does it appear to behave differently to mine. I've never had a full-on collision alarm going backwards, only the auto brake plus distance warning.

[nu11eaf]

I had the park assist unavailable message one day while driving in very poor weather after the roads had been salted, after cleaning the bumper sensors and restarting the car all was well again, so it could also be a simple matter of road dirt on sensors.

[Hadajag]

Originally Posted by Lexman8

Is it definitely the full-on collision alarm (dab on the brakes, alarm and head-up display) rather than an auto brake plus distance warning?


Your car does it appear to behave differently to mine. I've never had a full-on collision alarm going backwards, only the auto brake plus distance warning.

I am not sure what the difference is
In my case I get brakes hard on plus red flash on display plus loud tone.
Whatever it did not work when required apparently due to a battery error. It is these battery errors that concerns me most and are causing problems of various sorts to other forum members.

[LRS]

When arguing back and forth with Volvo UK about my AAOS XC60 dead car issue and the fact that they could not diagnose why, and even tried to make me pay for a new 12v battery that was less than a year old, that I said to them that one day this 12v battery issue will result in a safety issue.

To my knowledge, Volvo has never come clean on the 12v battery issue, apart from them maybe adding in a ‘deeper-sleep’ mode when the car is not used for an extended period of time, to reduce battery drain. (this still needs to be confirmed)

I eventually got so tired of fighting with Volvo UK (they hope you will), that I conceded and took my dealers suggestion and bought a trickle charger for the 12v battery.

[Hadajag]

Thanks. I refuse to accept that I should put a modern car with an only 2 year old battery on a trickle charger. The alternator should recharge the 12V battery even on short journeys. It is not as if this battery is even called upon to start the engine.
I wonder whether I could use my motor legal assistance
to bring a case agaiinst Volvo?

[LRS]

It may also be worth contacting The Motor Ombudsman regards this possible safety issue.

I raised a case against Volvo UK / Volvo Sweden, through The Motor Ombudsman, because Volvo stealthily removed core features from their audio system when moving from Sensus to AAOS and this not being specified in any of their sales materials (removing the audio balance and fader controls). They agreed to take on the case and were very helpful and easy to consult with, but unfortunately because my issue was not a safety or warranty issue, they were unable to pursue my case further with Volvo. From my experience, The Motor Ombudsman could be very interested in this 12v battery issue – especially as it could now be contributing to a safety issue.

Believe me, Volvo UK will play hardball and try every trick in the book, but with The Motor Ombudsman supporting you, Volvo has to be more amicable.