Fenix Flashlights | World Leader in Fenix® Sales | Fenix Lighting USA

Fenix ARB-L21-4000P Rechargeable Battery

Fenix ARB-L21-4000P Rechargeable Battery - Main image
$16.09 $25.95 In stock

Category: Accessories

ARB-L21-4000P is a high-capacity 21700 Li-ion rechargeable battery built for longer runtimes at higher levels. These battery allows a high output flashlight like the LR35R to have its turbo setting of 10000 lumens to maintain it’s output by maintaining higher voltage for longer periods of a batteries charge. Additional features include a protection circuit in the anode to help prevent short circuits, over charge/discharge and over heating. Pressure relief vents which expel waste gas in the rare case of an internal short circuit preventing an explosion. Battery capacity up to 4000mAh. 500 charging cycles. Important Note: THIS BATTERY IS NOT COMPATIBLE WITH 18650 FLASHLIGHTS OR OLDER STYLE CHARGERS. COMPATIBLE CHARGERS ARE THE ARE-A2, ARE-A4, ARE-D1, ARE-D2, OR ARE-X1 V2.0.

Specifications of the ARB-L21-4000P Rechargeable Battery

  • 21700 battery type
  • 4000mAh high capacity
  • Protection circuitry to prevent short circuits
  • Pressure vents to prevent explosions
  • 500 charge cycles
  • Compatible with Fenix lights that require a 21700 type battery.

Capacity: 4000mAh
Voltage: 3.6V
Charging Current: Recommended 1A, maximum 4A
Maximum output current: 18A (less than 3 minutes)
Maximum continuous output current: 10A
Weight: 2.5 ounces (70g)
Size: Length: 2.99″ (76mm) Diameter: 0.85″ (21.5mm)
Warranty Period: 12 month from date of purchase

Before you pay

Check the method and total at checkout.

When it ships

Allow for processing time as well as the journey to you.

Standard Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

Express Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

View policy
If you need a refund

Keep your order number and contact the store to start.

Please contact us for the refund processing timeframe before returning an item.

View policy
Delivery costs

Review the cost for your destination and chosen service.

Standard Shipping · United States: $0.00

Express Shipping · United States: $3.99

View policy
Returning an item

Check the return conditions before sending anything back.

United States · Return window (days after delivery): 30. Return method: By mail. Return postage: Seller pays.

View policy

Customer Reviews (5.0 / 5 · 5 reviews)

Violet D. ★★★★★

The 4000mAh capacity is the real deal—my light runs noticeably longer on turbo before stepping down. Managed three full nights of trail use without swapping cells, and it charged back up in just over an hour.

Michael ★★★★★

My old 21700 batteries would sag in the first minute of turbo, but this one holds steady and the whole light just feels more alive. The extra capacity between charges is a real upgrade for someone who uses high mode daily.

Scarlett R. ★★★★★

The 4000mAh capacity is no joke — I got a full night of use on high without the light dimming once. Charges up quickly too, so it’s easy to top off before heading out.