Premium high-discharge rechargeable batteries Fenix 21700 4000 mAh (ARB-L21-4000P) with electronic protection (protected) are designed for discharge currents up to 18 A. Li-ion rechargeable batteries are characterised by very high capacity, do not suffer from memory effect and have no self-discharge. Li-ion in 21700 size are the best choice in terms of stored energy relative to battery dimensions and weight, and are gradually becoming established in, for example, the automotive industry.

Protection of Fenix batteries consists of internal safety mechanisms and protective electronics. Added electronic circuits prevent overcharging of the cell, excessive discharge and also short circuits or excessively high current draw. If the battery electronics detect that limit values have been reached, they safely disconnect the cell. Internal protection consists of a separator, the most modern protection against overheating (PTC - Positive Temperature Coefficient) and a special anti-explosion valve. If the gas pressure in the cell exceeds a certain threshold, the internal separator isolates the electrodes inside the battery and thereby effectively interrupts the exothermic reaction, and the anti-explosion valve releases excess gas pressure from the battery. Thanks to the combination of electronic and mechanical (thermal and pressure) protection, Fenix batteries are among the safest available Li-ion rechargeable batteries.

This battery is designed especially for use in the LED torch Fenix LR35R. However, it can also be used in torches Fenix HT18, PD36R, TK22 V2.0, TK22 UE. It cannot be used in torches designed for 18650 batteries due to its larger dimensions. Due to the battery length of 76 millimetres (including protective electronics), it can only be charged in chargers that are adapted for this length. See recommended chargers below.

Fenix 21700 5000mAh battery specifications:

• Nominal voltage: 3.6 V
• Capacity: 4000 mAh, tested with discharge current 0.2 C with termination at voltage 2.5 V and temperature 25°C
• Maximum current draw: 18 A (max. for 3 minutes, long-term 10 A)
• Maximum charging current: 4 A
• Dimensions: 21.5 mm (diameter) x 76 mm (length) (+/- 0.5mm)
• Weight 70 grammes
• Protection against overcharging, complete discharge and short circuit (>18 A). The protective circuit is attached to the positive pole.
• Service life more than 500 charging cycles
• Recommended operating temperature: 0-45°C (charging), -20 to +60°C (discharge)
• Package contents: one Fenix 21700 4000mAh battery (ARB-L21-4000P).

Recommended chargers
Due to the battery length of 76 millimetres (including protective electronics), it can only be charged in chargers that are adapted for this length and are listed below. It will not fit in other models. Fenix ARE-A2 USB charger Fenix ARE-D1 USB charger Fenix ARE-D2 charger Fenix ARE-A4 USB charger SC2 USB charger SC1 charger

Warning
If possible, do not discharge the battery below 2.5 V Do not short-circuit the battery (do not connect the cell poles with a conductor) Do not throw the battery into fire or water Never insert the battery into a charger in reverse (with opposite polarity) When using the battery, observe safety principles Use only an appropriate charger that supports Li-ion batteries Warranty Two-year warranty.

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