S40 Stop/start

[robcmar]

Originally Posted by Clan

All the secondary battery does is keep the car's electrics going whilst stopped , leaving the main battery fresh to start the engine ..
Dont go to halfords for a battery , a genuine volo one is cheaper .. don't go buying batteries before youa re 100% sure yours is faulty .
Talking of batteries the stop/start batteries are special AGM batteries .
You are better off seeing the dealer , they have experience of why the stop/start doesnt work now after 2 years .
The reason for not stopping ( as well as hoards of other data ) is stored in a memory to read out .
Sometimes you can get it working again by disconnecting the battery for 5 minutes ..

Would that be disconnecting the main battery ? Not sure how to get to the secondary one !

[Clan]

Originally Posted by robcmar

Would that be disconnecting the main battery ? Not sure how to get to the secondary one !

yes the main battery , the secondary one is isolated at rest with everything off.

[robcmar]

Disconnected the battery and left it for 40 minutes. No change, stop/start still not working.

[Clan]

Originally Posted by robcmar

Disconnected the battery and left it for 40 minutes. No change, stop/start still not working.

fair enough that has eliminated that ..
Next you need to get the battery up over 80% Charged , you will need a 20 A charger to get it charged in a reasonable time say overnight , a small 3 or 4 amp charger can take days ..

[robcmar]

Originally Posted by Clan

fair enough that has eliminated that ..
Next you need to get the battery up over 80% Charged , you will need a 20 A charger to get it charged in a reasonable time say overnight , a small 3 or 4 amp charger can take days ..

Cheers Clan, will try that if I can borrow one. Will keep the thread informed but may take a few days.

[robcmar]

Forgot to mention I think that when I first got the car last week the low battery message flashed up. Didn't worry as it started first time and I then did a 90 mile round trip, enough to charge it up I thought. However, the message came up again yesterday, though it started first time again. Have now got a charger and will charge it tomorrow.

[Clan]

Originally Posted by robcmar

Forgot to mention I think that when I first got the car last week the low battery message flashed up. Didn't worry as it started first time and I then did a 90 mile round trip, enough to charge it up I thought. However, the message came up again yesterday, though it started first time again. Have now got a charger and will charge it tomorrow.

thats interesting , the stop start cuts off if the main battery goes below 80% charged , put a volt meter across the battery when the engine is running it should be over 14 v ... possible alternator problems ?

[volvorocks]

Originally Posted by Clan

thats interesting , the stop start cuts off if the main battery goes below 80% charged , put a volt meter across the battery when the engine is running it should be over 14 v ... possible alternator problems ?

As Clan says check the alternator is chucking out the charge, the correct voltage. Make sure its reaching the battery. Check at the battery.If it is not, it may be some connection somewhere between the alternator and battery. I had this on xc60, where the alternator was putting out the correct volts, but there was a drop by the time it reached the battery - resulting in various messages flashing up on the dash. (and flat battery)

I am not technical, just passing on what happened to me. Clan is the technical one!

Regards

[robcmar]

Originally Posted by Clan

thats interesting , the stop start cuts off if the main battery goes below 80% charged , put a volt meter across the battery when the engine is running it should be over 14 v ... possible alternator problems ?

Just tested it with the engine running, no electrical equipment on, it showed 14.24V.

Is it possible I have not got the correct permutaion of buttons pressed ? All I've done is press the stop/start button and it lights up. Is that all there is?

[Clan]

Originally Posted by robcmar

Just tested it with the engine running, no electrical equipment on, it showed 14.24V.

Is it possible I have not got the correct permutaion of buttons pressed ? All I've done is press the stop/start button and it lights up. Is that all there is?

the stop start defaults to ON with the green light on , you dont need to do anything .. So the alternator seems to be charging ok , switch on headlamps and heater fan and rear demist and rev engine to 2000 rpm . the voltage should stay the same or drop slightly , should still be over 14 v though //
With your power save message it would seem the battery isnt fully charged for some reason , can you get it tested ? remember it is an AGM flat plate battery , the latest technology , quite rare on a car .. It will need to be tested with this in mind for the correct result .