To compare solar fan batteries, read the capacity together with the battery's nominal voltage. Milliamp-hours (mAh) describe electrical charge; watt-hours (Wh) express nominal energy. A larger mAh number does not necessarily mean more stored energy when the voltage or the way the capacity is reported differs.
What mAh, volts and Wh tell you
| Label | What it describes | How to use it |
|---|---|---|
| mAh or Ah | Electrical charge capacity; 1,000 mAh equals 1 Ah | Compare alongside the voltage and the capacity reporting basis |
| V | Voltage; use the battery's stated nominal voltage for energy conversion | Check that it belongs to the same battery pack as the capacity figure |
| Wh | Nominal battery energy | A useful common unit for comparing battery energy |
| W | Power, rather than stored energy | Identify whether the figure describes the fan, a solar panel or a charger |
The U.S. Energy Information Administration explains watts and watt-hours: power describes the rate of energy use, while watt-hours account for energy over time. A panel marked 20W therefore does not describe a 20Wh battery, or prove that the fan motor consumes 20W.
Convert mAh to Wh with the matching nominal voltage
Use this relationship when both values describe the same battery pack:
Nominal energy (Wh) = capacity (mAh) × nominal voltage (V) ÷ 1,000.
Here are hypothetical labels for teaching the calculation. They are not Farseen specifications or measured results.
| Example battery | Capacity | Nominal voltage | Calculated nominal energy |
|---|---|---|---|
| A | 5,000 mAh | 3.7V | 18.5Wh |
| B | 5,000 mAh | 7.4V | 37Wh |
| C | 10,000 mAh | 3.7V | 37Wh |
B has the same mAh figure as A but twice the calculated nominal energy. B and C have different mAh figures but the same calculated nominal energy. Neither comparison, by itself, tells you which complete fan will run longer.
Do not multiply a battery's mAh by the solar panel voltage or by a USB output voltage. Those values describe different parts of the system. Anker's explanation of battery and output capacity illustrates why changing the voltage reference and allowing for conversion losses changes the capacity reported at an output.
Read ambiguous labels before doing the arithmetic
Some listings show two capacity numbers, such as a number followed by another in parentheses. The second number might use a different reporting basis or refer to a configuration, but punctuation alone does not establish which interpretation is correct.
For example, the current Farseen reference listings reproduce these entries:
| Model | Battery entry as supplied |
|---|---|
| 198F 16-inch standing fan | 18650 · 7.4V · 6000mAh (12000mAh) |
| S600 18-inch standing fan | 18650 · 11.1V · 6000mAh (18000mAh) |
The meaning of the parenthetical figures has not been confirmed for a specific order configuration. We therefore do not publish a pack-energy comparison by selecting whichever number looks larger. Ask for one clear statement of complete-pack nominal voltage, complete-pack Ah or mAh, and nominal Wh, tied to the model and battery revision.
Similarly, “18650” identifies a cylindrical cell format; it does not, by itself, establish the chemistry, replacement compatibility or service life of the finished battery pack. Do not open a fan's battery housing to investigate the label. A photo of an accessible product label, the manual or a supplier specification is the appropriate starting point.
Why Wh still does not promise a runtime
Nominal energy is a comparison point, not a guarantee that all of that energy reaches the motor. Actual runtime also depends on usable battery energy, the fan's power demand, speed, battery condition and any lights or devices drawing power.
A useful comparison asks two separate questions:
- How much nominal energy does each complete pack store? Use consistent V, Ah and Wh entries.
- How long does the complete fan operate under my conditions? Compare recorded results at the intended speed with the same additional loads and a clearly defined stopping point.
For the second question, use the solar fan runtime calculation guide and the explanation of how fan speed changes battery life. A supplier's broad runtime range should retain its stated conditions; it should not become an all-night promise in a product comparison.
A four-line battery comparison checklist
Before choosing a fan or comparing a bulk quotation, record:
- The exact fan model and battery configuration revision.
- The complete pack's nominal voltage and capacity, using a consistent reporting basis.
- The stated nominal Wh, or a calculation using confirmed matching values.
- The runtime test conditions, including speed, lights, USB loads and starting charge indication.
If one line is missing, mark it as unconfirmed rather than substituting a different voltage or adding together unexplained capacity figures. Buyers can carry these entries into the supplier quotation comparison table; home users can use them when checking the specifications of a particular fan.
Common questions
Is a 12,000mAh fan always better than a 6,000mAh fan?
No. The comparison needs the nominal voltage, the reporting basis and the power demand of each fan. Even at the same nominal energy, different complete fans can have different runtimes and operating characteristics.
Can I use the USB output rating to calculate battery capacity?
No. A USB output rating describes an output, not necessarily the battery pack's nominal voltage. Use matching battery values for nominal Wh; output energy also involves the device's conversion and operating limits.
Does a higher voltage mean stronger airflow?
Voltage alone does not establish airflow. Compare the complete fan's measured performance and controls. The 198F and S600 comparison separates confirmed configuration differences from performance that still needs a comparable test.
Farseen Editorial Team
The Farseen Editorial Team publishes practical guides and company updates about solar rechargeable fans, off-grid appliances, and product sourcing. Where an article discusses product-specific details, refer to its cited sources or contact Farseen for current information.