Jaguar XF 2015 stop start function

[Jack Giles]

Hi there,

I have a 2015 XF 2.2D (2008-2015 version). Had the car for 4 years and the stop start function has never worked. I noticed if I drive for roughly 30 mins + the stop start light will come up on dash.

Id like to start with charging both main and aux battery, is there any specific procedure to follow when doing so? 

I have a basic battery charger. It says it's a smart charge and covers AGM, cost around £25 do you think this is suitable? 

What V should I expected from both batteries with engine off and on?

Any other suggestions would be great.

Thanks so much in advance for anyone's help!

[Big John]

Hi jack

To be honest if you have had the car 4 years and not replaced the battery it is probably due a new one. Battery charger you have may be OK but personally I would be wary. Jaguars (like all modern premium cars) are a collection of computers and networks with a wheel at each corner. As such they use a LOT of electricity and get upset (refuse to work properly) when their supply gets a bit iffy. I use a CTEK Stop/Start which are about £80.... Voltage varies drastically. When fully shut down and sleeping voltage if fully charged should be 12.6v+.

As soon as you unlock the car it can be drawing up to 20A so voltage drops quickly to not much over 12.2. When engine is running mine is about 14.8v

[Jack Giles]

Hi John,

Thanks, I checked the main battery last night it sat at 12.5V car off and 14.7V car idling, you still think it'd worth charging up before replacing it? 

 

I will look at better charger, is there anything specific I need to do prior apart from negative clamp to chassis of car?

Thanks!

jack

[Big John]

...Those voltages sound OK.

Could be the auxilliary battery but just re-read your original message. The Stop/Start light should only come on when the car is actually stopped and the engine has shut off as a result of an auto stop. It then goes off when the engine restarts. If it is coming on with the engine running it sound like an issue. Have you tried reading for any error codes? When you press the eco button on the dash do you get a message saying it is turned off or on? When manually turned off there should be an icon in the info panel showing the symbol with line through it. The green symbol on the dash comes on when the stop/start is active.

John

[Jack Giles]

Hi John, 

 

I just check smaller battery, it's resting at 7V and 14.5V when car idling. 

I've also attached a photo of warning light that come on after driving for 30 mins