Stop & Start

All Citroen Aircross related discussions
srperry
Posts: 306
Joined: Fri Mar 01, 2019 10:32 am
Location: Wiltshire, UK

Post by srperry »

I was once told by a professional mechanic that you needed to complete a run of around 20 miles to replace the energy used for one battery start, so I don't think it's too surprising that multiple stop/starts in a 7 mile journey don't get fully refreshed, even allowing for how much technology has moved on since I was told that. The technolgy in your car appears to be working correctly; the reason stop/start is disabled is to ensure that you have enough charge left to start the car from cold and to supply the alarm system etc, when it is being left for a time.

My car is kept garaged most of the time, and since lockdown my mileage has dropped considerably. If I don't use it for a week the stop/start doesn't usually work immediately, especially if the climate control is running - but it does recover after about 15-20 miles of running.
Was C5 Aircross PureTech 130 S&S Flair, Tijuca Blue/Black Roof, Metropolitan Grey ambience
Now C5 Aircross Pureteh EAT8 S/S Shine+ Cumulus Grey/Black Roof, Metropolitan Grey ambience

sandychc
Posts: 5
Joined: Thu Oct 01, 2020 7:04 pm

Post by sandychc »

Thanks for that Beanee. Let me know if they solve it.
routemaster1
Posts: 365
Joined: Wed Mar 27, 2019 7:57 pm

Post by routemaster1 »

Using the climate control doesn't automatically disable stop/start as the aircon usually only operates intermittently. If the system decides to kick in whilst the engine has stopped it will trigger a restart.
Deleted User 830

Post by Deleted User 830 »

I already posted some information on the other Stop & Start thread:

viewtopic.php?f=8&t=648&p=3313#p3313

For optimum operation of the Stop and Start function, the vehicle must be driven regularly. Several days of not driving the vehicle can result in non-availability of the Stop and Start function (the battery charge status is below the minimum required threshold measured by the battery charge status unit):
  • The seat belt must be fastened
  • The engine coolant temperature must be within the nominal operating range
  • The outside temperature must be between 0 and 35°C
These are the minimum thresholds as measured by the BCSU (Battery Charge Status Unit) in order for the Stop and Start function to be operational - so the values must be equal to or greater than those below:
C3AC Stop Start BCSU.PNG
One other important thing to consider after charging the battery: You must wait between at least 4 hours and one full night after fully charging the battery without touching the vehicle. This is the time needed for the status of the battery to be properly measured by the BCSU to change from inaccurate > 10% to nominal < 5%).

So doing anything like opening the vehicle doors, unlocking it or operating any equipment like the radio will interrupt the measurement process.
Airtool
Posts: 237
Joined: Sat Nov 28, 2020 11:30 am

Post by Airtool »

Very informative, but i cannot believe in this day and age that with the millions of cars with day time lights, flat screens, alarms, start & stop and cd/radios that the last two will not work on a Citroen because the battery threshold is finely monitored.
How does other car manufactures manage, larger alternators, bigger batteries ? And don't start using the cigar lighter you may not get it off the drive, thereagain perhaps Citroen may intend supplying a cranking handle.
C3 Aircross Flair 110bhp 2020 grey
russbif
Posts: 62
Joined: Fri Nov 27, 2020 1:59 pm

Post by russbif »

Stop start was introduced by manufacturers to meet the EU emission control legislation, nothing more nothing less.
They may package it up as being environmentally friendly, but at the end of the day it’s all about beating the meter when on the rollers.
That’s why VW fiddled their ecu’s.
Deleted User 830

Post by Deleted User 830 »

It's all about getting more out of less. They need smaller engines and equipment to meet stricter Euro requirements. So more plastics, more recyclable components, less weight etc etc.

But the C3 Aircross has different battery options depending on equipment and engine.

Mine being a 1.5 Diesel with my options requires a L3 battery, 760A / 70AH
Level 2 Batteries are 640A / 60AH

So if you intend on replacing the battery with a higher capacity one, it will be important to have the BCSU configured to tell it you have the higher rated battery (i.e. a L3 instead of a L2) depending on what you had to start with of course.

When you consider the electronics and the number of ECUs on these later vehicles - all requiring power round the clock in some cases, a weak battery or one with diminished capacity is one of the biggest causes of faults in many cases. These days you will be lucky to see 5 years life out of a battery (depending on use) before it starts to lose its capacity to hold a charge. 60-80% of original capacity is not unusual after this period or less.

That's without all the additional strain of demisting (A/C and cabin heating resistors), heated rear window, the wipers, camera, lights, and the rest of it.

I bought an expensive Bosch AGM battery for my last C5 that had every option and I could never get a minute out of the radio before economy mode kicked in. The same thing happened - unless you do the miles and regularly, the battery is constantly being drained when not in use - I found I had to regularly take the battery off for overnight recharging during lockdown - at least every 2 weeks!

So I eventually put it into Park mode to shut off most of the power consuming equipment and that worked a treat. It meant I could leave the car for a good month when not in use and it would still be relatively snappy when starting.
russbif
Posts: 62
Joined: Fri Nov 27, 2020 1:59 pm

Post by russbif »

I bought my C3 Picasso in December 2009, it was still on its original battery when I sold it last year with 86k on the clock. Most reliable car I ever had, apart from the steering rack motor failing around 80k.
Beanee687
Posts: 642
Joined: Tue Jan 28, 2020 10:22 pm

Post by Beanee687 »

My stop start, as I have said previously, runs well for so many weeks then stops. It is restored to function by an overnight charge. I fitted a new ammeter to my charger on Monday and with a battery terminal voltage of 12.71 I put the charger on. The ammeter showed 1.5 amps current flow. After 13 hours the battery terminal voltage was 13.42 and current flow 0.2A. I disconnected the charger and as before the stop start works again.
This battery is 12 months old car has done 3340 miles.
2023 C3 Aircross Shine+ 130 BHP EAT6.
Pepper red with red roof and black mirrors & roof bars
russbif
Posts: 62
Joined: Fri Nov 27, 2020 1:59 pm

Post by russbif »

Wouldn’t an “off” switch be nice? Not the fiddly touchscreen that always defaults to on.
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