Reading the model code
BD6A- Family segment. The 6A here is the balance-current class, not a pack rating: what governs JK-BD6A20S20P is 0.6A active balancing, and the class comes with the family rather than being chosen separately.
20S- Maximum cells in series, which is roughly 64V nominal with LiFePO4 cells. It is a ceiling: nothing is wasted by running fewer cells.
20P- Continuous discharge position. The spec table on this page lists 200A, and that is the figure to size cable, terminals and the protective device against.
What actually changes between these codes
The closest step below this board inside BD6A is JK-BD6A20S15P: same 20S ceiling, same 0.6A balancer, only the continuous rating moves, to 150A. US$27.68 separates the two at the base configuration. Size that gap against the load actually drawn, because nothing else about the two boards changes.
Same current, different ceiling: JK-BD6A24S20P runs to 24S where this board stops at 20S, which is a 76.8V nominal pack instead of this board's 64V. Choose on the cell stack, because no setting converts one into the other.
JK-B2A20S20P is the other candidate for the same pack: 20S, 200A, 2A balancing rather than 0.6A. It sits US$40.17 above this listing at the base configuration. If the cells are matched and the duty cycle leaves idle time, the cheaper of the two is the right answer; if they are not, no protection setting replaces balance current.
26 BD6A codes are priced here, from US$47.98 for JK-BD6A17S6P to US$175.68 for JK-BD6A32S15P; JK-BD6A20S20P is 22 of that set at US$106.81 before configuration options. The spread across the family is a ratings spread rather than a margin spread, so quote the cheapest code that clears the calculation.