Six months ago my car wouldn’t startup in the morning. I replaced the battery by buying a new one from the dealer. Now, the same problem is shown again and dealer replaced the battery for me again. However, the problem isn't solved and the battery drained in 48h. I tried to find any abnormal current drains, but we can’t find anything. Recently I know all batteries which are provided by dealer was manufactured in 2016. Can that be the problem? Are the batteries too old to work (worn out before I get them)?