21700 Li-ion Batteries & Cells
21700 Li-ion Batteries & Cells
32 products
21700 batteries are lithium-ion cells 21mm across and 70mm long, and they power long-range FPV quads, mapping drones and radios that need flight time more than punch. This page covers every 21700 product in our Li-Ion Batteries & Cells range: loose cells for building your own pack, and ready-made packs in every common layout from 1S to 12S. Two numbers matter most: capacity, typically 4200–5000mAh per cell, and continuous discharge current, which must cover what your motors draw at cruise and on climb-out.
How to choose 21700 cells or packs
- Cell: the Molicel P42A (4200mAh) is the proven high-discharge cell, the P45B (4500mAh) adds capacity at a similar 45A rating, and the P50B (5000mAh) is the highest-capacity option. The Reliance RS50 is another 5000mAh option.
- Configuration: "6S2P" means six cells in series and two in parallel. Series cells set the voltage (25.2V fully charged for 6S); parallel groups add capacity and current.
- Discharge: Li-ion delivers far less current than LiPo, so size the pack so cruise current stays well inside its rated continuous discharge. Adding a parallel group (2P, 3P) doubles or triples the current the pack can supply.
- Connector: packs are offered with XT60 or XT90 anti-spark plugs; pick the one that matches your drone's power lead.
What we stock
Loose cells include the Molicel INR-21700-P45B and P50B and the Reliance INR21700-RS50. Ready-made packs are built in India on Molicel cells: P42A packs from 1S1P to 12S3P and P45B packs from 3S2P to 8S3P, covering everything from single-cell builds to 12S heavy-lift airframes. For radios there is a RadioMaster 2S 5000mAh transmitter battery.
Compatibility
Li-ion packs suit efficient builds with modest current draw: 7-inch and larger long-range quads, fixed-wings and mapping multirotors on low-KV motors. They are a poor fit for 5-inch freestyle, where hard punch-outs make the voltage sag heavily.
Set your flight controller's low-voltage warning lower than for LiPo: Li-ion can be run down to around 3.0V per cell under load, against roughly 3.5V for LiPo. Charge on a charger with a Li-ion mode (4.2V per cell), and balance-charge packs that have a balance lead.
When building your own pack, use cells of the same model and batch, and spot-weld nickel strip rather than soldering directly to the cells.
Frequently asked questions
- Li-ion or LiPo for a long-range drone?
- Li-ion packs hold more energy for their weight, so they fly longer at a steady cruise. LiPo delivers far more current for punch-outs, so many long-range pilots fly Li-ion for distance and LiPo for freestyle.
- What is the difference between the Molicel P42A, P45B and P50B?
- The P42A (4200mAh) is the older, proven cell; the P45B (4500mAh) adds capacity at a similar 45A continuous rating; the P50B (5000mAh) is Molicel's newest and highest-capacity 21700, rated for 60A. All three are high-discharge cells suited to drone packs.
- Can I build my own 21700 pack?
- Yes, with a spot welder, nickel strip, a balance lead and proper insulation; never solder directly to the cells. Use matched cells of the same model and batch in each pack.