What changes at this size besides the warranty?

Three things. The case material goes from ABS to polypropylene, the terminal goes from an M5 insert to an M6, and the country of origin goes from Vietnam to Taiwan. The design life does not change: every XTV part is rated up to 12 years in standby service at 25°C. The one year of additional warranty is the commercial expression of the Taiwan build, and on a submittal that asks for country of origin, this is the first XTV block that answers Taiwan.

Why is the short circuit current so much higher than the XTV12200?

Plate area and internal resistance. This block sits at approximately 5.20 milliohms against 12.2 for the 12200, and short circuit current is close to the terminal voltage divided by that resistance. At 1,627 amps for five seconds, a string of four in series will drive a fault at the same current, so the DC fuse or breaker upstream of the string has to be rated to interrupt it. Ask for the figure to be written into the protection study before the cabinet is energized.

How should I read 56.0 Ah against the 55 on the price list?

The datasheet figure is the measured one at the 20 hour rate to 1.75 volts per cell; the price list carries CSB's commercial nominal. Use 56.0 for a runtime calculation and 55 where a procurement document asks for the manufacturer's catalog rating. The difference is under two percent and either can be defended with the document it comes from.

Does the polypropylene case change anything for an outdoor cabinet?

Not in how the battery is handled or mounted. PP and ABS are both rated UL 94-HB on these blocks, and both are offered in a 94-V0 flame retardant version on request at a surcharge. If the enclosure specification calls for a V-0 container, name it on the order rather than assuming; the CSB price list lists FR as an option on every XTV part, not as standard equipment.