What is the Formula for Converting Wh and mAh?

Converting watt-hours (Wh) to milliampere-hours (mAh) requires factoring in voltage (V): Wh = (mAh × V) / 1000. For reverse calculations, mAh = (Wh × 1000) / V. These formulas link energy capacity (Wh) to charge storage (mAh), critical for comparing batteries. Voltage defines the relationship—ignoring it causes errors. Example: A 10,000mAh 3.7V battery stores 37Wh. Always verify device voltage for accurate conversions.

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What’s the core formula for Wh to mAh conversion?

The primary equation is mAh = (Wh × 1000) / V. Voltage bridges energy (Wh) and charge (mAh). Without it, conversions are guesses. For instance, 50Wh converts to ~13,514mAh at 3.7V (smartphone) but just 4,545mAh at 11V (laptops). Pro Tip: Label batteries with both metrics—simplifies cross-device compatibility checks.

Understanding voltage’s role is key. A 100Wh battery could be 27,027mAh at 3.7V or 9,090mAh at 11V—same energy, different applications. Why does this matter? Devices like drones need high mAh for sustained current, while solar generators prioritize Wh for total energy. Real-world example: Anker’s 26,800mAh power bank (96.5Wh at 3.6V) fits under airline 100Wh limits. But what if you mislabel voltage? A 96.5Wh pack rated at 5V falsely becomes 19,300mAh, risking device incompatibility. Always cross-validate specs.

Why can’t you convert Wh to mAh without voltage?

Voltage determines energy per charge unit. Higher voltage means fewer mAh for the same Wh. Omitting V is like comparing fuel tanks by volume without knowing fuel type. For example, 100Wh equals 27,027mAh at 3.7V but 8,333mAh at 12V—a 225% difference. Pro Tip: Use manufacturer voltage specs, not charger outputs.

Battery chemistry dictates voltage ranges. Lithium-ion cells run 3.2–3.7V, while lead-acid systems use 12V. Let’s say you’re comparing a 300Wh LiFePO4 camper battery (24V, 12,500mAh) to a 300Wh power station (12V, 25,000mAh). Same energy, but the camper battery delivers half the mAh due to doubled voltage. How does this affect real-world use? A 12V 100Ah marine battery (1200Wh) outlasts a 3.7V 324Ah power bank (1200Wh) in trolling motors but not in smartphones. Conversion tools that auto-detect voltage (like Redway’s calculator) prevent mismatches.

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How do Wh and mAh differ in practical use?

Wh measures total energy; mAh measures stored charge. Devices like EVs use Wh for range estimates (energy per km), while mAh suits small electronics (phone screen-on time). Example: A 5000mAh phone battery at 3.7V holds 18.5Wh, enough for 8 video hours. Pro Tip: Use Wh when comparing cross-voltage systems.

Energy-hungry tools (e.g., circular saws) depend on Wh—a 20V 5Ah (100Wh) pack lasts twice as long as a 10V 10Ah (same 100Wh). But mAh-focused marketing can mislead; a “30,000mAh” power bank sounds impressive until you realize it’s 111Wh at 3.7V, not 370Wh if incorrectly assumed at 12V. Transitioning between metrics, solar installers care about Wh/day for system sizing, while RC hobbyists track mAh to balance drone thrust. Ever wonder why electric planes use Wh/kg? Energy density rules aviation, whereas mAh/kg matters more for low-voltage robotics.

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