Buy the supported pack in the quantity you need.
Capacity is per battery. Package count, charger support and exact tool requirements are separate decisions.
Match all three components
Record the exact tool, battery and charger models before shopping. Follow the manufacturer-supported pairing, including any qualifications in the tool manual. A shared voltage label or brand does not resolve compatibility across separate battery families.
Keep capacity and count separate
DCB205 is a single 5 Ah battery; DCB205-2 supplies two of that battery. The second package does not become a single 10 Ah pack. Compare the capacity per battery, pack count and included charger rather than collapsing them into one number. An Ah label also does not establish a runtime for your task.
Check charging and simultaneous needs
Milwaukee 48-59-1812 supports documented M12 and M18 packs with sequential charging. That support does not interchange the two tool families or imply simultaneous charging. Also check the exact tool’s pack requirement: a two-battery tool needs a different available-power plan from a one-battery tool.
Decide what the extra pack solves
A second supported pack may serve another tool or your planned charging rotation. Define that need first, then check the exact package and battery condition. This catalog does not promise a performance gain, fixed work time or current saving from buying more packs.
