Here's a quick how to video that I made showing replacing the stock 12v 45AH lead acid battery with a 12v 70AH AGM battery.
Some folks have had issues with the stock 12v battery running down and not being able to unlock the vehicle, or start it by remote, or some to even start it at all, as it is needed to engage the relays for the high voltage battery. Some also get the "Deep Sleep" message in the FordPass app that indicates a low battery voltage for the 12v battery.
Adding a larger AGM battery helps to prevent these issues.
Besides topping up the AGM battery prior to install, it took about 20 minutes.
Edit - The 12 volt battery is under the floor in the rear cargo area. In the Titanium hybrid, the spare tire covers it, so remove the spare tire to see it. In the SE hybrid, there is no spare tire, so you'll see it once you lift up the floor of the rear cargo area. - Edit
I might do the larger battery install eventually. But for now I went ahead and got myself a super cap boost pack to keep in the car. Autowit 2 brand. Plus then I can jump other people without worry of toasting my own cars electrical system.
I'd assume they mean they swapped from the smaller stock lead acid to larger AGM battery.
Not sure why you'd want to try charging past 100% SoC. Unless it wasn't configured right to begin with. Say set for 80Ah, but you have a 100Ah battery, so it's fine to put in 125% of 80Ah (1.25*80=100).