Samsung - INR18650-35E - 3.7v 3400 mAh

Samsung INR18650-35E 18650 Li-Ion Rechargeable Cell – 3.7V 3400mAh – Technical Specifications:

Handy Tips for Using the Samsung INR18650-35E Li-Ion Cell:

1: The Samsung 35E is a high-energy density cell — it prioritises maximum capacity and runtime over high discharge current. With 3,500mAh nominal capacity, 3.60V nominal voltage, and 8A continuous discharge, the Samsung 35E is well suited for battery packs, backup power systems, LED lighting, portable energy devices, and other low-to-moderate current applications. It is not the right choice for very high current loads — for those applications, a high-drain cell such as the Samsung 25R or 30Q is more appropriate.

2: This cell is unprotected and flat top — it contains no internal protection circuit. Always pair it with an appropriate BMS (Battery Management System) providing overcharge protection (cutoff at 4.2V), over-discharge protection (cutoff at 2.65V), overcurrent protection, and short circuit protection. Never use unprotected Li-Ion cells in any application without a BMS in place.

3: The maximum charge current is 2,000mA (0.6C). Never charge this cell at a higher rate — unlike high-drain cells rated for 1C or 2C charging, the 35E is optimised for capacity over charge speed. Fast charging above 0.6C accelerates internal degradation and heat buildup, shortening cycle life significantly. Always charge using a CC-CV method: constant current to 4.2V, then constant voltage until current drops to approximately 170mA (0.05C cutoff).

4: At 15A discharge the cell temperature rises above 75°C — 15A is definitely too high a current for this cell. Keep continuous discharge within the recommended 6A optimal and never exceed 8A continuous. For burst loads, 13A is the absolute peak for very short durations only. Sustained high current discharge causes rapid heat buildup, capacity loss, and shortened cell life.

5: When building multi-cell battery packs, always use cells from the same batch with matched capacity and internal resistance. Before assembling, measure the open-circuit voltage of each cell and ensure all cells are within 0.05V of each other. Mismatched cells cause uneven charging and discharging, accelerating degradation — especially dangerous in series configurations where weaker cells can be driven into reverse polarity.

6: ⚠️ Li-Ion Safety Warning — Li-Ion cells can cause fire or explosion if mishandled. Never short circuit, puncture, crush, expose to water, or subject to temperatures above 60°C. Always charge on or near fireproof material and never leave charging cells unattended. Store spare cells in a hard non-conductive case — never loose in a pocket or bag alongside metallic objects. If a cell becomes hot, swells, or emits odour, move it immediately to a safe outdoor location away from flammable materials.