I have a 2016 Volvo V60 Premier Drive E with Start/Stop feature. Is there a secondary battery in the car? If so where? Owners manual does not say so. Volvo Corporate Customer Service was no help except they mentioned there was a secondary battery for Start/Stop and info can be found in Owners Manual. No luck there.

Original 3.5 year old Volvo AGM battery rated at 760 CCA. Start/Stop became not available all the time with accompanying on screen notes in My Volvo Car saying power reserved for Climate Control System and Electrical System. Tested battery and it needed replacement. I put in a new AC Delco AGM 850 CCA battery and the Electrical System note dropped off but Start/Stop availability turns on and off when AC is on even at first morning start before engine is warm and behaves the same way throughout the day whether warm out or not. As soon as AC compressor kicks in or I select on/off with AC off the Start/Stop becomes unavailable. Alternator is okay. Dealer telling me the Volvo Control System requires specific battery with a specific discharge rate to properly turn on and off. I am not interested in buying another $400 battery and could live without Start/Stop but if it is only a secondary battery then I would like to evaluate replacement. Local repair shop that installed new AC Delco is researching and came across a note about Secondary Battery as well. Hoping to cut research time by local shop and get my 2-2.5 mpg change back. Also want everything working when I decide to trade in or sell for a new one.