Battery Unit Conversion Tools

mAh indicates how much charge a battery can deliver over time and is common for small batteries. Higher mAh = longer runtime at the same voltage.

Wh measures total stored energy. It already accounts for voltage: Wh = (mAh × V) / 1000 or Wh = Ah × V.

Ah is capacity for larger packs. Multiply by voltage to get energy in Wh. Example: 100 Ah at 12.8 V ≈ 1,280 Wh.

Voltage is electrical potential. Common system “nominal” voltages: 12 V, 24 V, 48 V. Lithium cells are typically 3.2–3.7 V nominal per cell depending on chemistry.

Ampere is current flow. For DC systems, W = V × A. For AC, use W = V × A × PF.

Watt is power (rate of doing work). Energy (Wh) = Power (W) × Time (h).

Apparent power in AC systems (ignores power factor). Generators/UPS are often rated in kVA.

Real/usable power. kW = kVA × PF. Utility bills show energy in kWh, not kW.

Energy over time. 1 kWh = using 1 kW for 1 hour = 1000 Wh.

PF (0–1) shows how effectively current is converted to useful work. Many motors have PF ≈ 0.7–0.9.

They describe the same thing at different scales. 1 Ah = 1000 mAh. Use Ah for large packs (e.g., power stations), mAh for small devices.

Nominal voltage is a convenient label (e.g., 12.8 V for LiFePO₄), while actual voltage varies with state of charge, load, and temperature.

Capacity (Ah) doesn’t include voltage. Energy (Wh) = capacity × voltage. Always compare packs in Wh/kWh across different voltages.

DC: W = V × A. AC: W = V × A × PF. Low PF means more current for the same real power—important for inverter sizing.

C-rate expresses charge/discharge current relative to capacity. A 1C discharge on a 100 Ah battery is 100 A; 0.5C is 50 A.

Depth of Discharge (DoD) is how much you’ve used; State of Charge (SoC) is what remains. Many LiFePO₄ packs are rated for 80–100% DoD cycles.

LiFePO₄ typically offers longer cycle life, better thermal stability, and flatter voltage curves; NMC offers higher energy density but often fewer cycles.

Inverters are not 100% efficient (often 85–94%). There’s also idle/standby consumption. Size the battery with losses in mind.

Motors/compressors need higher short-term start (surge) power. Ensure your inverter/generator supports both surge and continuous ratings.

Series increases voltage (Wh increases with same Ah). Parallel increases Ah (Wh increases with same V). Match chemistry, age, and capacity when combining.

Undersized cables cause heat and voltage drop. Use thicker wire for high current and long runs; keep DC runs short.

Cold reduces available power; heat accelerates aging. Many LiFePO₄ packs restrict charging below ~0 °C to protect cells.

Lead-acid capacity falls at higher discharge rates. Lithium is far less affected, which is why it sustains higher loads better.

MPPT controllers harvest more energy (especially in cold/variable sun) by tracking panel V-I curves; PWM is simpler but less efficient.

The Battery Management System handles cell balancing and protects against over/under-voltage, over-current, short-circuit, and over/under-temperature.

A UPS prioritizes seamless switchover (<10–20 ms or less). An inverter/charger may have longer transfer times unless designed as UPS.

Look for certifications (e.g., UL, IEC, UN38.3 for transport). Follow manufacturer limits for charge current, discharge current, and temperature.

Horsepower (HP) is a unit of power originally defined by engineer James Watt to compare the output of steam engines to the work of draft horses. Today it is commonly used to measure the output of engines and motors.

• Mechanical horsepower: 1 HP = 745.7 W (U.S. standard)
• Electric horsepower: 1 HP = 746 W (used for electric motors)
• Metric horsepower (PS): 1 HP = 735.5 W (common in European automotive specs)
• Boiler horsepower: 1 HP = 9809.5 W (used for steam boilers, ≈ 9.81 kW)

For practical conversions, you can estimate: 1 HP ≈ 746 W ≈ 0.75 kW. This makes it easier to compare engines or motors rated in horsepower with electrical devices rated in watts or kilowatts.