Just replaced the battery in my 2014 and noticed what appears to be a second battery near the primary. Does it need to be replaced periodically? What purpose does it serve?
My owners manual is silent on the subject.

 

It is for the auto stop/start function to work to improve fuel economy by turning the engine off when the car is idling at a stop sign. If that function still works in your car then that battery is probably ok. BTW many people hate the stop/start function and remove this battery to defeat it and save some weight. This function no longer works in my car so that battery is probably kaput.

 

If you want or need a replacement it is an Exide EK151.
Don't get it from the dealership as they will charge you double or triple for the same battery with a Jaguar sticker on it.

 

Great information. I didn’t pay much attention to the loss of the stop/start feature as I don’t care for it. Probably won’t replace that battery. It’s good to know there is a common replacement available.
Thanks for the info.

 

After my second one went dead after warranty expired I took over whelming forum advice and did not replace it, don't miss function at all.