The Dell Latitude 7280 has two main battery options: a 3-cell, 42 WHr battery and a 4-cell, 60 WHr battery. Both are rechargeable, lithium-ion batteries, though the 3-cell battery operates at a higher voltage (11.4V) compared to the 4-cell (7.6V).
3-cell battery
Capacity: 42 WHr
Voltage: 11.4V
Cell type: 3-cell Lithium Prismatic
4-cell battery
Capacity: 60 WHr
Voltage: 7.6V
Cell type: 4-cell Lithium Prismatic