Sanyo 20700B 3.7 V 4250 mAh lithium-ion battery with tabs

High-capacity 20700 cell for custom packs

The Sanyo 20700B is a lithium-ion cell rated at 4250 mAh and 3.6 V nominal voltage. It is intended for experienced builders who assemble their own battery packs and understand the safety requirements of spot-welded tab terminals. The 12 A maximum discharge current supports moderate power applications. Buyers who need a ready-to-use consumer battery with built-in protection circuitry should look elsewhere.

Thermal behaviour and power draw

At the standard 2 A charge rate the cell accepts energy without excessive temperature rise when adequate spacing and airflow are provided. Internal resistance remains low enough that typical discharge currents well below the 12 A limit generate minimal heat. The 63 g weight and 20.35 mm diameter allow compact pack layouts that do not trap heat. No active cooling is required for normal use within the specified current range.

Sustained-load performance

Continuous operation near the 12 A ceiling will raise cell temperature progressively and demands careful thermal management in the pack design. Voltage sag under heavy load stays predictable down to the 2.5 V discharge cut-off. Repeated deep cycles at high current reduce overall cycle life compared with lighter loading. The welded tabs maintain a stable connection throughout extended discharge sessions.