They usually don't turn off. They reduce the charging current based on the battery's voltage.
It's actually better to leave the battery connected to the car, especially with one as new as yours. BMW and VW are well-known for locking up multiple computers just from disconnecting the battery to replace it. They say it's for theft control, but we all know it's to force you to have the car towed to the dealer to have the computers unlocked. GM is famous for such tricks too, but I haven't run into that yet as far as starting the engine. My friend just rebuilt a 2022 Chevy truck and found he can't read or erase fault codes and the parking brakes were stuck on. Had to trailer it to the dealer and have the computer reset for $600.00. I haven't heard of anyone having trouble yet with a Ford. I have two 2014 Dodges, and with both of them, nothing noticeable happens after reconnecting the battery. All the memories, including things like express windows with their learned forces are still in memory.
The reason for these battery maintainers is all of the computers draw some current to keep their memories alive. As far back as the late 1980s, Chrysler allowed up to 35 milliamps, (0.035 amps), for "ignition off-draw" (IOD) current, and at that rate, a good, fully-charged battery would still be strong enough to crank the engine fast enough to start after sitting for three weeks. Today that is the industry standard unless the manufacturer specifies otherwise. Cadillac is one that allows 50 milliamps. If you disconnect the battery's negative cable, (or both of them), there will be no IOD current and no need for the maintainer.
Jan 13, 2024 at 6:05 PM
