How Many Watt-Hours Is 2,000 mAh at 12V?
At 12V, 2,000 mAh converts to 24 Wh nominal. That is (2,000 × 12) ÷ 1000. After DC-DC conversion and chemistry losses, around 20.4 Wh is what a connected device typically sees. The nominal figure is what airline Wh limits check against; the usable figure is what sets real runtime.
Tiers apply to nominal Wh. Spare batteries travel carry-on with terminals protected; airlines can impose stricter rules. See airline-limits section below for the full conditions.
Use this citation when referencing this page.
Formula
Wh = (mAh × V) ÷ 1000
Battery & Travel Info
FAA Airline Battery Limits
The FAA (and most international regulators under ICAO) set the following Wh ranges for lithium-ion passenger-flight battery carriage. The limits apply to the nominal 24 Wh figure, not the usable figure, so the airline checks the same number you get from the mAh × V calculation above.
| Wh Range | Typical Rule | This Battery |
|---|---|---|
| ≤ 100 Wh | Generally allowed in carry-on without airline approval | Within range |
| 100-160 Wh | Carry-on typically requires airline approval | -- |
| > 160 Wh | Generally not permitted on passenger flights | -- |
Conditions that affect how the rule applies: spare (uninstalled) lithium batteries must travel in carry-on, not checked baggage, with terminals protected against short circuits (original packaging, terminal caps, or individual plastic bags). Batteries installed in a device follow different rules than spares. Quantity limits typically permit up to two spare batteries in the 100-160 Wh range per passenger with approval, with no fixed limit on spares under 100 Wh for personal use (airlines can still restrict). Specific carriers and jurisdictions impose their own rules on top of the FAA/ICAO baseline. Check your airline's dangerous-goods page before travel; this table is a reference starting point, not a guarantee.
Device Runtime Estimates
How long will a 2,000 mAh / 24 Wh battery power common devices? Runtimes apply an 85% conversion-efficiency factor (usable energy ≈ 20.4 Wh). Device wattages below are planning figures, not measured averages for any specific model, and real runtime varies with screen brightness, CPU load, wireless radios, and ambient temperature.
| Device | Power Draw | Estimated Runtime |
|---|---|---|
| Smartphone (screen on, browsing) | 2W | 10.2 hours |
| Tablet (mixed use) | 4W | 5.1 hours |
| Ultrabook laptop (browser + docs, screen at 50%) | 15W | 1.36 hours |
| LED flashlight (medium setting) | 3W | 6.8 hours |
| Bluetooth speaker (medium volume) | 1.5W | 13.6 hours |
Estimates assume 85% conversion efficiency. Actual runtime varies with temperature, battery age, and usage patterns.
Charging Time
Time to fully charge 24 Wh at each common charger rating, assuming about 85% charging efficiency (heat losses in the charger IC and the battery's internal resistance mean less than the charger's rated watts actually reach the cell). Raw math is 24 Wh ÷ (charger watts × 0.85).
| Charger | Estimated Time to Full |
|---|---|
| USB 2.0 (5W) | 5.65 hours |
| USB-C (18W) | 1.57 hours |
| Fast charge (25W) | 1.13 hours |
| USB-C PD (45W) | 37.65 minutes |
Real charging rarely holds the charger's full rated wattage end-to-end. Most chargers taper as the battery approaches 80-100% (constant-current then constant-voltage phases), so actual time-to-full is often 10-25% longer than the table figure for the last 20% of charge. Treat these as ballpark planning times, not guarantees.
Same mAh, Other Voltages
| Voltage | Wh | FAA/ICAO tier |
|---|---|---|
| 3.7V | 7.4 Wh | ≤100 Wh, generally allowed carry-on |
| 7.4V | 14.8 Wh | ≤100 Wh, generally allowed carry-on |
| 11.1V | 22.2 Wh | ≤100 Wh, generally allowed carry-on |
| 12V | 24 Wh | ≤100 Wh, generally allowed carry-on |
| 14.8V | 29.6 Wh | ≤100 Wh, generally allowed carry-on |
| 24V | 48 Wh | ≤100 Wh, generally allowed carry-on |
| 48V | 96 Wh | ≤100 Wh, generally allowed carry-on |
Tier labels mirror the FAA/ICAO baseline. Individual airlines and jurisdictions can impose stricter rules on top, and the spare-vs-installed distinction and terminal-protection requirement still apply. See the airline-limits section above for the full conditions.