Hi, I bought a new DS7 in February 2025 and despite being turned on, the Stop / Start function has never worked. There is almost 2000 miles on the clock now which has included long drives of 50+ miles and a 250 mile return trip.
I called in with the dealer yesterday. I was told that the battery needs to have a minimum charge level (75-80% ?) for this feature to work, but assuming that a new car contains a brand new battery, along with the long trips undertaken that I expect would boost the charge, I’m not convinced by this suggestion. The dealership ‘reset’ the Stop / Start function but after a 50 mile journey back home, it has still not worked.
I will appreciate any thoughts from the Forum members…
Bit odd that the S/S doesnt work at all.
I do low mileage, probably around just 50 miles per week over 4 days, the car is then parked up for 3 days, theres still only 1500 miles on the clock after 7 months but my S/S still works.
My DS4 has been back to the service dept many many times over the last 7 months since buying the car new last September, after having issues with the keyless entry & welcome lights , they changed both 12v batteries under warranty but the issues came back shortly after, they then said its due to the low mileage !
Now though they think the main 12v battery could be faulty again and will be checking it again over the next few weeks.
When I queried how a new battery can go faulty so soon the DS Master Technician told me that DS use reconditioned batteries, even in their brand new cars !!
Apparently if your battery has a black casing it most likely a new/recon battery , I’m not sure how much truth is in this, but after all the trouble I’ve had with batteries it wouldn’t surprise me.
Theres a number of posts online regarding issues with batteries across the DS range, theres some on here as well.
Theres a number of reasons why the S/S does not kick in, low battery is definitely one of them, engine temp, exterior ambient temp, power usage such as A/C ect , but after a 50 mile non stop journey I would say you could discard temps and accessory usage, however, if your 12v battery or batteries (theres 2 of them) are not getting or holding a charge, even even after a 50 mile journey, that could almost definitely be your problem.
You could try a trickle charge over night from a “Smart Charger”, I use a Ctek MXS7., it will charge and check your battery, and if faulty will indicate the fault.
This is how it was explained to me, your main 12v gets its charge from the alternator, the smaller 12v then gets its charge from the main 12v battery, it’s a one way open circuit, so the charge goes into the main 12v and carries on through to the smaller 12v battery, the circuit does not allow current to flow from the smaller battery back to the main battery, thats why disconnecting the two batteries has to be done in a certain sequence., which is shown in the manual.
The alternator on the DS4 E Tense is a “Smart” alternator it also holds a small amount of charge, I dont know why, but thats what they told me.
Not sure if your DS7 would have the same type of alternator, but I would imagine it would have the same battery set up, ie: two 12v batteries, one main and one smaller one.
Hi JacTac, thank you for your response & the helpful thoughts/suggestions.
I should have stated that my car is a 1.5l BlueHDI (Pallas) so I suspect it has only one battery??? I did wonder if it might be a battery issue - my longest non-stop drive was about 250 miles and it didn’t function even then. My previous car was a DS5 and at about 3 years old, the S/S function also stopped working. A new battery resolved the problem for a few days! I was then advised that I needed a new BMS (battery management system) which I think was around £500. I got the BMS replaced and the S/S did work very occasionally afterwards although mostly didn’t.
Following your comments, I will seek an independent assessment of the battery. The S/S is not a major issue for me (I do love the car) but as a brand new car, it seems reasonable to expect that all features should be working…
I might be wrong but it could very well have two batteries, many cars with S/S have two.
There’ll be the main 12v under the bonnet, and a smaller “back up” hidden away somewhere, mine is hidden inside the car under the central console.
These new modern cars have so much tech its not like testing a 12v on the older ford cortinas (showing my age now).
The BMS on these cars is very techy, you can charge your car up manually but after a day or two the BMS will settle the voltage to around 80%, again this is how it was explained to me.
I dont understand why the BMS does this ?
I do know though from experience, that many DS owners have reported issues with S/S, and other features which were caused from battery issues.
The S/S on my Volvo V40 was forever knocking off, I would charge the batteries up over a weekend, nice and slow, the S/S would work for about a week then knock off again, yet when the batteries were tested they were fine.
But if I went for a good long drive the S/S would start working again, it was those little journeys that the BMS didnt like so would hibernate the S/S.
Like me, as its a brand new car I want definite answers , there has to be a reason why these things are intermittently working.
I’m currently being looked after by DS customer care, but in fairness my dealership are also trying their best to sort things out.
My issues from day one was the keyless entry and welcome lights not always working, they did loads of software updates, changed both keys, a module, and two batteries, they now think its a software issue but are not 100% convinced that the batteries they changed are fully working, the main one is showing as a bit low again, hence the technician mentioning that DS use recycled batteries, so its being monitored, the car is due to go back to be checked next week I think.
I have a DS7 - 2018 also BlueHDi - the S/S has never worked since I purchased it 6 months ago (used). I presumed the battery was not up to spec, I thought maybe the PO swapped it out.
I’m not bothered as if it did work I would disabled it.