| Nominal Voltage |
3.6 V / 3.7 V |
Many specs list “3.6 V nominal” or “3.7 V nominal.”
|
| Fully Charged Voltage (Cutoff) |
~4.20 V ± 0.05 V |
Standard Li-ion charge termination (CC/CV) voltage.
|
| Overcharge Protection / Max Allowed |
~4.30 - 4.35 V |
The protection circuit often clamps / cuts off charging when voltage rises beyond standard safe limit. E.g. in a datasheet: 4.325 V ± 0.05 V for protection board overcharge cut-off.
|
| Discharge Cutoff (Safe Lower Limit) |
~2.50 V ± 0.10 V |
Below this, the protection circuit prevents further discharge to avoid damage.
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| Over-discharge protection |
~2.50 V |
As above, built into protection PCB.
|
| Maximum Discharge Current (with protection) |
Varies (e.g. 5 A, 6 A) |
Because of the protection circuit, the allowed continuous discharge current is limited. For example, one “protected 18650 2600 mAh (button top)” claims ~6 A continuous discharge.
|
| Over-current / short-circuit protection |
Typically a few A |
The protection circuit may trip / open on sudden large current draw (short) to protect the cell. Eg. some specs mention “over-current protection” as a feature.
|
| Capacity (Nominal) |
2,600 mAh |
That’s the “2600 mAh” rating (often measured at a standard discharge rate)
|
| Minimum / Guaranteed Capacity |
~2,500 mAh |
Many manufacturers guarantee a minimum (e.g. 2,500 mAh) under standard conditions.
|
| Internal Resistance |
≤ ~120 mΩ |
One spec sheet (for a version with protection) lists ≤ 120 milliohms (1 kHz measurement)
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| Standard Charge Current |
~0.2 C (≈ 520 mA) |
Some datasheet specs show the “initial charge current” at 520 mA (0.2C) under standard charge.
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| Rapid / Fast Charge Current |
≈ 1C (≈ 1,300 mA) |
Some specs allow a faster 1C charge rate under controlled conditions (if the cell and PCB support it)
|
| Charge Termination / Cutoff Conditions |
By time or current drop (e.g. when current drops to ~0.01C) |
E.g. in a spec, “by current drop: 26 mA (0.01C)” is used to determine end of charge.
|
| Cycle Life |
≥ 300 cycles (to 70%+ capacity) |
The standard spec might guarantee 300 cycles (at modest charge / discharge rates) before capacity degrades to ~70% of initial.
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| Self-Discharge |
≤ ~2% / month at 20 °C |
Some datasheets mention ≤ 2%/month at 20 °C, increasing at higher temps.
|
| Operating Temperature (Charge) |
0 °C to ~45 °C |
Standard safe range for charging (ambient)
|
| Operating Temperature (Discharge) |
–20 °C to ~60 °C |
Typical discharge ambient limits |
| Storage / Shelf Temperature |
–20 °C to ~25 °C (1 year); up to ~45 °C for shorter durations |
Many datasheets limit long-term storage at elevated temperature.
|
| Dimensions (outside with protection / sleeve) |
≈ 18.5 mm diameter × 65.0 mm height (± tolerances) |
Typical for 18650 battery form factor. |
| Weight |
~45–50 g |
Many protected 18650s of 2,600 mAh fall in this weight range; one spec lists ~47 g.
|
| Protection Circuit Features |
Overcharge, Over-discharge, Over-current, Short-circuit protection |
The “protected” label typically implies that the battery has a small PCB which monitors cell voltage, current, and sometimes temperature, and disconnects the cell under abnormal conditions. |
| Maximum Size with Protection |
Some extra length from the protection circuit / tabs |
Because of the added PCB and terminals, the overall package (sleeve, protection board, tabs) can slightly exceed the bare cell dimensions. One protected model (KeepPower P1826K) lists “maximum size: 18.6 × 68.9 mm (±0.2 mm)” (diameter × length) including protection components.
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