Packs like these are normally spot welded together with nickel strips. Lithium-ion, or Li-ion typically refers to the overarching technology of rechargeable lithium batteries, but also specifically refers to the traditional cells built in cylindrical metal bodies. The venerable 18650 is one such cell, but a large variety of sizes and types exist.
To make the battery pack, you have to first finalize the nominal voltage and capacity of the pack. Either it will be in terms of Volt, mAh/ Ah, or Wh. You have to connect the cells in parallel to reach the desired capacity (mAh ) and connect such parallel group in series to achieve the nominal voltage (Volt ).
Commonly cells in parallel are abbreviated in terms of ‘P’, so this pack will be known as a “5P pack”.When 5 cells are connected in parallel, ultimately you made a single cell with higher capacity ( i.e 4.2V, 17000 mAh ) Voltage (Volt) : The desired nominal voltage of the battery pack is 11.1V. The nominal voltage of each cell = 3.7 V
The desired nominal voltage of the battery pack is 12.8V. The nominal voltage of each cell = 3.2 V No of cells required for series connection = 12.8 /3.2 = 4nos Commonly cells in series are abbreviated in terms of ‘S’, so this pack will be known as a “4S pack”.
A 4S pack of LFP is the most common replacement for a 12V Lead-Acid battery pack (4P X 3.2V = 12.8V nominal). That being said, NCA/NCM in the 18650-format cells have a much better selection of choices, and provide high power and long range in a small package that is affordable, due to mass-production.
The top pack is an HV type. Lithium-HV, or High Voltage Lithium are lithium polymer batteries that use a special silicon-graphene additive on the positive terminal, which resists damage at higher voltages. When charged above 4.2V, most lithium batteries exhibit significant capacity loss and reduced lifespan.