Precision On-Board Chargers: Choosing Bank + Battery Type

From the title: CHOOSING Bank + Battery Type.

I guess I was expecting to see how to know if my WEISS LIFePO 100AH could be safely charged on different size Minn Kota On Board Chargers. How will I know if my battery is a 5 amp, 7 amp or 10 amp for example...which would drive which charger to get.

I did not get that from the video.

So do I hold down the button after I select the correct type? The instructions didn’t say. Nor the video.