Hi Joe,

Yep I’m an EE. You know “Double the Voltage, Double the Flux, Double E, Double E, Double E, Sucks”. An old Collage expression the Mechanical Engineers use to say to us EE.

Anyway, The Quote you posted from Johnson Control is correct on the CCA. However Reverse Capacity make no sense to me. Back to my example of a rating of 40amp/hr; If you attach let’s say a radio to a battery that has a rating of 40amp/hr and this radio draws 10 amps from the battery, than the battery will last 4 hours before it is dead.

What you Quoted from Johnson Control makes no mention of the type of load that is on the battery. A light load will allow the battery to last longer than a heavy load.

Back to your question; Why does a normal aspirated engine have a smaller battery than a turbo engine? Well I would assume that it has to do with cost. Normal Aspirated engines are install by Volvo into cars that are sold as low-end models. You know cars that have no bells and whistles. No thrills. Hence Volvo wants to keep the cost down. Where as the high-pressure turbo engines are installed in the high-end models. Lot of bells and whistles. Therefore, it takes a battery with more current reserve to run those bells and whistles. Other than this I can see no other reason. The starter would be the same and engine compression would not make that much of a difference. If engine compression did make a difference than a normal aspirated engine has a higher compression, which would mean you need a battery with more capacity and not less.

I Hope this helps,

Good luck,

Steven---