Illustrative render of the Amprius INR21700-65 cell✱ Render
Illustrative render generated from published specifications. Not a photograph of the actual cell.
21.6 × 71 mm · 74 g
21700NMC Mooch-tested · 13 A

Amprius INR21700-65

Amprius · released 2025
Capacity6500 mAh23.4 Wh · 316.22 Wh/kg
Mooch continuous13 ASize to this figure
Resistance3.3DC internal resistance
Voltage window3.6 V2.5 – 4.2 V
Standard charge3250 mA~2 h to full

At 6500 mAh, this ranks #1 of 72 21700 cells in our database. Near the top for capacity among 21700 cells. More capacity than 100% of 21700 cells in our database, but lower discharge than average.

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Full specifications

Electrical
ChemistryNMC
Nominal voltage3.6 V
Max charge voltage4.2 V
Discharge cutoff2.5 V
Max continuous discharge13A (Mooch-tested)
Mooch CDR (trusted)13 A
Standard charge current3250 mA
Standard discharge current1300mA
Internal resistance3.3 mΩ
Physical
Form factor21700
Dimensions21.6mm × 71mm
Weight74 g
Top typeFlat Top
ProtectedNo
Performance
Capacity6500 mAh
Energy23.4 Wh
Specific energy316.22 Wh/kg
Energy density899.41 Wh/L
Power density (gravimetric)632 W/kg
Power density (volumetric)1,799 W/L
Cycle life500 cycles
Year released2025
Operating Limits
Charge temp0°C to 45°C
Discharge temp-20°C to 60°C

Independent test data: Mooch's test of the INR21700-65 ↗

At the standard 3250 mA charge rate, a full charge takes about 2 hours. The last bit is a slow taper to top it off.

Voltage operating window

Cutoff
2.5V
Nominal
3.6V
Max charge
4.2V

Usable range: 1.7V

C-rate conversion: Amprius INR21700-65 (6500mAh)

C-RateCurrent (A)Theoretical runtime
0.2C1.3 A5h 00m
0.5C3.25 A2h 00m
1C6.5 A1h 00m
2C13 A30m

Highlighted row is closest to the rated 13A continuous discharge.

Charging

RateCurrentEstimated time
0.5C3,250 mA~2h 00m
1C6,500 mA~1h 00m

These are estimates for the constant-current phase. Real charge time is a bit longer because of the slow taper at the end.

Datasheet

Pack scaling

Series voltage configurations

ConfigNominal VMax VMin VCommon use
1S3.6V4.2V2.5VFlashlights, single-cell devices
2S7.2V8.4V5VRC vehicles, 7.2V packs
3S10.8V12.6V7.5VPower tools (10.8V nominal)
4S14.4V16.8V10VEbike (small), some power tools
7S25.2V29.4V17.5VEbike (24V system)
10S36V42V25VEbike (36V system)
13S46.8V54.6V32.5VEbike (48V standard)
14S50.4V58.8V35VEbike (52V high-power)
16S57.6V67.2V40VDIY powerwall

Parallel capacity scaling

ConfigCapacityEnergyMax discharge
1P6,500 mAh23.4 Wh13 A
2P13,000 mAh46.8 Wh26 A
3P19,500 mAh70.2 Wh39 A
4P26,000 mAh93.6 Wh52 A
5P32,500 mAh117 Wh65 A
6P39,000 mAh140.4 Wh78 A

Example pack configurations

7S2P
24V ebike / small pack
14 cells25.2V nominal13,000mAh328Wh26A maxCell weight: 1.04 kg (add ~15% for wiring and BMS)
13S4P
48V ebike standard
52 cells46.8V nominal26,000mAh1217Wh52A maxCell weight: 3.85 kg (add ~15% for wiring and BMS)
16S4P
DIY powerwall
64 cells57.6V nominal26,000mAh1498Wh52A maxCell weight: 4.74 kg (add ~15% for wiring and BMS)
4S6P
Power tool replacement
24 cells14.4V nominal39,000mAh562Wh78A maxCell weight: 1.78 kg (add ~15% for wiring and BMS)

Design a custom pack with this cell:

Application suitability

PowerwallsHigh capacity means more stored energy per cell. Fewer cells needed for a given kWh target.
Ebike PacksGood balance of capacity for range and discharge for hills. Works well in most ebike packs.
Car AudioMight work for smaller setups. Check your amp's peak current draw.
High-Drain VapingBelow the 25A Mooch CDR threshold that high-drain vaping needs. Use a higher-drain cell.
FlashlightsHigh capacity means long runtime. Great for everyday carry and extended use.
Power ToolsMay work for lighter-duty tools. Check your tool's current requirements.

Physical dimensions

Dimensions21.6mm × 71mm
TopFlat Top
Format21700

Similar cells

Same format and chemistry, within ±500mAh capacity:

CellmAhCDRWhWeightWh/kg
Amprius INR21700-65 (this cell)650013A23.474g316.22
BAK 65E650025A23.4
Linkdata 65P650052A23.470.2g333
Vapcell F63625012A22.5
Linkdata 60P600060A21.668g318
Vapcell F60600012A21.674g292

Frequently asked questions

Handling and safety

Lithium cells can be dangerous if mishandled. A few things to keep in mind:

  • Never charge above 4.2V or discharge below 2.5V.
  • Store cells at around 3.6-3.8V (roughly 40-60% charge) for long-term storage.
  • Don't mix cells with different capacities, chemistries, or states of charge in a pack.
  • Inspect wraps before use. A torn wrap can cause a short circuit.
  • Always use a BMS or balance charger appropriate for your pack configuration.
  • Keep cells away from metal objects, keys, and coins. A short across the terminals can cause fire.

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Specs come from manufacturer datasheets and independent testing; Mooch-tested discharge ratings are shown when available because they reflect real continuous performance better than headline datasheet numbers. Browse the full 18650 & 21700 cell database to compare every cell.

Disclaimer: We do our best to keep the information on this page accurate, but we cannot guarantee that all specifications are correct or up to date. Cell characteristics can vary between production batches and may change over time. Do not rely solely on this data for safety-critical applications. Always verify against the manufacturer's official datasheet before use.