New and Old Batteries in Parallel

[JimC]

My service battery is a good quality 110 amp/hour one which seems to hold its charge well and has never been deeply discharged or abused, but it's three years old. I would like to connect a second battery of the same type in parallel with it to double the capacity. Would I have any problems arising from the different age of the two batteries?

 

[VicS]

Probably not while the old one is still "good" but when it gets a tad geriatric it'll probably affect the performance of the combined bank before its younger companion start to deteriorate.