EVE Energy Co., Ltd. INR21700/50E
Series: EVE Energy Co., Ltd. Battery cells for drone packs
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The EVE INR21700/50E is the energy version of the 21700 round cells from EVE Energy, a Chinese maker of lithium batteries. At 5,000 mAh it targets small FPV drones built for flight time rather than current peaks. According to the IEC scheme, INR denotes a cylindrical lithium-ion cell with a nickel-containing cathode.
The nominal voltage is 3.65 V, giving about 18.3 Wh per cell (nominal voltage times capacity). Minimum capacity is 4,950 mAh, the weight 68.0 g with a tolerance of 2 g, the dimensions 21.15 × 70.15 mm. The maximum discharge current is given as 15 A, which is 3C. This value expressly does not apply to cycle-life ratings: anyone who runs the cell continuously at maximum current leaves the range for which cycle figures hold. Finished batteries with a protection circuit quote lower values, one example being 10 A continuous and 14 A briefly.
Six cells in series (6S1P) give about 110 Wh. The pack therefore lies between the IATA limits of 100 and 160 Wh; in that range the airline must agree, and above 160 Wh carriage on a passenger aircraft is ruled out. Transport also requires proof of UN 38.3 testing and terminals protected against short circuit. Joining cells into a pack belongs in a specialist workshop.
As an energy cell the 50E suits long, steady flights with low current demand, not freestyle with fast load changes. Voltage sag under load is larger at high current, and the internal resistance can be read from the data sheet. Cold increases the sag; buying from reputable dealers protects against re-wrapped cells.
Technical data
Other data
| C-rate | 3correct |
|---|---|
| Capacity (mAh) | 5,000correct |
| Cell chemistry | Li-Ioncorrect |
| Cell count (S) | 1Scorrect |
| Continuous current (A) | 15correct |
| Form factor | 21,700correct |
| Nominal voltage (V) | 3.65correct |
| Weight (g) | 68correct |
What to check before buying
- Check the hour meter against the service records — a replaced instrument is the most common gap.
- Compare the data plate and chassis number with the papers.
- Ask about parts availability for this build year — the running costs hang on it.
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