I installed a regular Amaron battery after getting fed up with the 2yr lifespan of the EFB even without using istop. Warning lights gone after an hour drive, tested istop once just to check if it's working, lasts 2 minutes in traffic like the stock EFB. After that, I just turn it off every drive.

A lot of CX-5 club members are using non-EFB Amaron for a few years now, no reported issues so far.