Thread: Auto Stop Start Battery

Are you sure its a battery? I have this little niggle thats saying capacitor in later models... maybe its an RRS thing?

I have no idea. It could be a super capacitor.

All I know is, Auto Stop/Start just stops working within a couple of weeks of a service. I am guessing whatever the device is, it is "charged" at service.

Some hate Auto Stop/Start with a passion and have to disconnect something to turn it off. I like it, and it stops all by itself. Very frustrating.

Cheers
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Yes,, its the first thing I do in the car, switch it off..
sounds like the capacitor has died..

I have asked on our FB page.. maybe JC will pop up...

Just add to the mistique...

I have just been on a 2 hour drive. It worked for about 5 minutes in the middle of it.

Go figure.............

Cheers
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Numb Thumbs,

I had a similar issue when I purchased my new-to-me 2019 D5 SDV6. Within days of my purchase, the Start/Stop routine stopped working, but it didn't worry me as I don't much care for it. Then the battery died. That is, the main battery died. $500 later, I had a new battery and the Stop/Start worked again. It's now six months later and Start/Stop is still working as it should.

I've seen various references to a separate stop/start battery but my understanding is that there's no such battery in D5. When looking to reuse an old Traxide auxillary battery charging setup, I learned a lot more than I need to know about D5 battery systems, including that it's so-called smart charging system does not actually charge the battery to full capacity. Apparently, it maintains some headroom to allow for top-up during regenerative braking. The smarts maintain a balance while driving, shutting off stop/start when it needs to top-up the battery. I've noticed this when sitting at traffic lights: the engine stops when I apply brakes and then, after a while, it starts again, even though I'm still with boot firmly planted on the brake. I assume this is just the smart alternator doing it's job of keeping the battery at a certain level of charge. I'm of the opinion that the absence of start/stop, in my case, was an indication that the battery was on its last legs.

My experience so far, reinforced by reports from others, is that D5 is a strange beast when it comes to its battery. Not wanting to be caught in the middle of nowhere with no battery to start the vehicle, I now carry one of those Lithium battery jumpstarter units. I haven't had to use it yet, and I hope I never need to, but it's comforting to know that I have something of a backup plan.

Mark

I have just driven 8 hours at 110 km/h, Melbourne to Sydney. The Stop/Start worked once - first time in months - at the first traffic light and not since.
If the aircon is on, the engine will restart to run the aircon.
Cheers
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PS Just driven back for 8 hours, non stop, at 110 km/h. Stop/Start not working at all. It only works straight after a service, it seems...

Hi. Sorry this is semi related to this as it is a battery issue. I too am finding this car to be a strange electrical beast. I have only had the car about 6 weeks and just purchased a new battery. Had traxide system in my previous D4 and was about to pull the trigger on one for this car before the battery went. Now really puzzled about the battery.

So, got home from fitting the new battery and installed a BM2.

Today was my first chance to look at the system with a known good battery.


Went out to the car at 8am (12.5 v). Drove out to do some tasks. When I left I put my OBDII reader on and to my surprise it was recording less voltage (12.2) than the BM2 was showing. Scratching my head over that but will need to monitor it on a longer drive.

When home I put it on battery charger (12.6 volts but I would have expected that some surface charge was present ).

Turned battery charger off at 2pm. Showed 14.3 volts but image still some surface charge there. Battery charger had not finished cycle. Car was unlocked with tailgate open.

Out 2.30pm, 13 volts showing on the BM2 before I left. 2km trip each way with car parked between. Single lock.

Back home 3.30pm car parked and locked. 12.6 volts showing on BM2 after car stopped. Seems like a lot of voltage drop in a short time but perhaps losing surface charge from the battery charger.


8.30pm. Checked via BM2 and found 12.3 volts. To me, that is a big drop in voltage for a parked car. The only accessories I have installed that use battery power are a tow pro elite v3 and the BM2 Battery monitor.

Double locked now waiting to see what happens overnight. Will repeat the process tomorrow. At 9.30pm showing 12.19 volts so still going down

So to bring it back to the Stop Start battery issue. Have you recorded any data on your battery use to see if that is perhaps impacting on your vehicle. Whilst this was only one days data for me it has me scratching my head. I know you have a DCDC charger system setup but I am unsure of how this might be impacting on the battery or if it impacts at all. Similarly I am totally unsure of what the Traxide system would do to the charging system. So is it an electrical system issue with an inability to keep a charge?

My thinking on the stop start "feature" is that manufacturers fir it to meet fuel consumption and pollution regulations, the same reasons for "smart" alternators and various other "features"
It certainly would have nothing to do with saving the customer money due to lower running costs and fuel consumption as replacing batteries, starters and other items having increased usage due to the sudden starts under load would surely negate any fuel savings.
Any new car I was considering buying would have to have the feature permanently disabled before I would even consider buying it. Along with that lane bipping and jerking that most new cars have these days.