This is not a deep cycle battery(nor should it be). If the battery gets discharged, and is not recharged promptly, it's life will be shortened. AGM or not, it's got to stay charged. In extreme cold, an AGM will fare better, as a discharged flooded battery is more prone to freeze.

Just trying to make sure nobody prematurely blames the battery.

 

Any loose connections will inhibit current flow, a rusty or loose ground wire especially. But a loose relay or fuse not so much.

 

problem solved: optima redtop battery was bad, no fault in vehicle!
got new battery as warranty.
...but noticed that waterpump leaks badly, now needs that and new cat converter. luckily had that ordered due rattle noises from exhaust.

 

The AC Delco oem one is doing fine by me. Almost 10 years & it passes the tests
But Ive been looking into what I would replace it with, interstate comes to mind. unless local dealer still sells the same oe batttery

 

Closing this thread.