Can an external BMS have much control over the battery itself as compared to a BMS integrated into the battery? After watching the video from your link I got the impression that it monitors the battery while managing accessories and charging. Whereas the BMS in the battery actively prevents damage to the battery and has no influence on accessories or charging. They seem antipodal.
I didn't even realize there was a (blocked) video on the Ford site.
Ultimately, they both "manage" the battery, but in two different contexts. One macro, one micro.
The macro, holistic system Ford is using, where the vehicle's central computer adjusts to battery condition by shutting down different systems, isn't a new concept, but more advanced in execution than those of 10, 20, 30 years ago, which would shut off things like dome lights after a pre-set period to not kill the battery. The modern Ford system is smarter, and draws from more data, but the battery being managed is still a conventional 12V lead acid battery.
When I see BMS referenced, I first think of the systems in electronic devices, like cell phones, which have some computing power and utilize lithium cells, which require active management to keep them, and their users safe.
Lithium batteries will sustain permanent damage if they are overcharged, or drained beyond a minimum voltage, and given their energy density, carry a higher risk potential if they are abused, or something goes wrong. One can get raw lithium cells, for use in things like flashlights, and vapes, but it's incumbent upon the user to act as the "BMS" in such applications, monitoring their voltage, and keeping the cells within the safe, happy range. The manufacturers recognize that, do not directly sell such cells to unintended users, and also plaster warnings over them.
The lithium car batteries that have come on the scene must have onboard BMS systems, to enable them to act like conventional 12V lead acid batteries, for conventional 12V vehicle electrical systems, and to make the lithium cells compatible with being charged with 3x the expected voltage, produced by a vehicle alternator.
One way to look them is like the fly-by-wire systems in aircraft which are inherently unstable, and need constant computer management to allow them to fly safely, something a pilot would not be able to achieve manually. They insulate the user, interpret the control inputs and translate them to the needed actions, and keep everything hunky dory and as intended.
Porsche has offered low capacity, lightweight lithium car batteries for special (racing) applications for a while.
But VAG has moved to lithium batteries as regular duty batteries, seen in their high end SUVs like the Lamborghini Urus, Porsche Cayennes, and the like.
Those batteries have onboard BMSes, and given the presence of repair services tailored to them, have not been entirely trouble free, but given a choice between a $500 repair of the BMS, or a new OE battery that lists for $4500, or $2000, respectively, one option is going to be more attractive than the other.
