The Fenix ARB-L21-6000 21700 rechargeable Li-ion battery has a capacity of 6000mAh, providing the necessary voltage and power for long-lasting use and increased lumen capabilities. With the same features as other high-quality Fenix batteries, such as internal protective circuits and up to 500 charging cycles, the ARB-L21-6000 can ensure extended runtime and consistent performance. It also offers three sets of overheat protection - pressure relief, microporous, and PTC cathodal block - to maintain the battery's safety and stability. Never be without light; order a spare 21700 battery today.
PRICE IS FOR ONE BATTERY
THIS BATTERY IS NOT AN 18650, AND IT IS NOT COMPATIBLE WITH 18650 FLASHLIGHTS. Recommended for use only in these Fenix products purchased in 2025 or later. Compatible products: TK16 V2.0, TK20RV2.0, TK22R, TK17, TK21R, TK30R, CL27R, WF25RM, HT18R, HT18RV2.0, HT32, PD40R V3.0, PD36R V2.0, PD36R-ACE, PD45R-ACE, LD45R, LD35R, LD36R, E35R, LR35R-Pro, LR36R, CP50R. Not compatible with older Fenix models that utilize a 21700 battery such as the Version 1 of the PD36R. COMPATIBLE CHARGERS ARE THE ARE-A2, ARE-A4, ARE-D1, OR ARE-D2. Will not work in older chargers such as the ARE-C1 and other "C Series" chargers. This is not the version of the battery with direct USB charging.
Shipping Note: Lithium ion batteries are considered "dangerous goods" per US transportation regulations and can often only be transported via ground shipment. Orders containing loose batteries will typically take much longer than predicted to be delivered. Delivery times of 14+ days are not uncommon.
Overall rating: 3.75 / 5 from 12 reviews.
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"I give a ☆☆☆☆☆ for there durability and there life span . Compared to other models and brands."
"MATERIAL SUPERVISOR"
"I have been a Fenix customer since 2014 and have spent $1000s on Fenix flashlights, headlamps, batteries, and accessories. I purchased 4 of the Fenix ARB-L21-6000 mAh Rechargeable 21700 batteries from Fenix Store on 11/28/25. They have to be forced into the Fenix ARE-A4 Multifunctional Battery Charger and then removed with a small screw driver since they cannot be removed otherwise. They also have to be force into my Fenix HP30R V2. 0 Headlamp - 3000 Lumens and then removed by aggressively and repeatedly tapping the edge of battery holder until enough of the battery comes out to be grabbed and pulled out by a pair of mini channel lock pliers. This process will eventually cause damage. After the first set of batteries ran out of a charge I replaced then with the second set of charged batteries and the headlamp would not work. The lid/cover to the battery pack/holder has to be forced shut so I don’t know if the inner coils are displaced to cause the failure of the function, or why it won’t work with the batteries stuffed in the pack. I replaced them with my older Fenix 21700 Rechargeable Li-ion Battery – 5000U mAh batteries and the headlamp worked. The whole reason I bought the 21700 6000 mAh batteries was to use in the headlamp that I use to work outside at night with and the 5000 mAh run out of charge so I have to replace them, more often and in the middle of a project, than the old 18650 battery headlamps and was hoping the 6000 mAh would last a bit longer. I am not sure what the engineers or corporate decision makers at Fenix are thinking but this battery either needs to be re-engineered or given a different label because it does not fit nor function in existing Fenix devices."
"This ARB-L21-6000mAh-21700, is one powerful and long-lasting battery. It took 5. 5 hours to charge from 3. 6V to 4. 20V, in a tabletop charger. A 21700-5000mAh battery, has about double the Watt Hour capacity of a typical 18650 battery. The 21700-6000mAh has 20% more Watt Hours than the 21700-5000mAh battery. Hence, IT IS, "A Powerful Beast". Also great for high current draw LED lights. It comes in its own protective PVC locking case. Buy it in pairs and get the extra protection of a foam padded, cardboard storage box."
"The Fenix 6000mah are a larger diameter than the Fenix 5000mah, and the Fenix 4000mah. They will fit in Fenix flashlights 🔦 but is going to be Extremely difficult to ever remove them! Why Fenix??"
"This L21 fits nicely into the Fenix PD40R V3. 0, but is slightly too big in diameter for the TK20R V2. 0 and the PD36R lights. It is spec’d at . 85” diameter, the same as the spec for the other Fenix L21 series batteries, but I believe it is slightly larger. For me, it is limited in use to the PD40R V3. 0. I am keeping it but a bit disappointed it won’t fit in my other Fenix L21-compatible lights."
"Great product fast shipping long life"
"The 21700 battery got stuck inside the light."
"These are a great replacement batteries"
"Great Batteries love the way you can charge them with the charging port on the battery."
