🔋 Battery Capacity Converter

Convert battery capacity between Ah, mAh, Wh, and calculate battery performance metrics.

Battery Voltage (for Wh calculations):

Volts

All Unit Conversions

Ampere-hour
100
Ah
Milliampere-hour
100,000
mAh
Watt-hour
1,200
Wh
Kilowatt-hour
1.2
kWh

🔋 Battery Performance Metrics

⚡
8.3A
Max Current (1C)
⏱️
100h
Runtime @ 1A
🔌
100W
Max Power Output
📏
150Wh/kg
Typical Density
🔋 Real Battery Capacity Examples
📱
Smartphone Battery
3.7V Li-ion
2000 mAh / 7.4 Wh
Typical phone battery
📲
Power Bank
3.7V Li-polymer
5000 mAh / 18.5 Wh
Portable charger
🚗
Car Battery
12V Lead-acid
100 Ah / 1200 Wh
Starting battery
🏠
Deep Cycle Battery
12V AGM
200 Ah / 2400 Wh
Solar/RV battery
🚗
Tesla Model S
400V Li-ion pack
75 kWh / 187.5 Ah
Electric vehicle
🔋
18650 Cell
3.6V Li-ion
4680 mAh / 16.8 Wh
Common cylindrical cell
🚲
E-bike Battery
48V Li-ion
50 Ah / 2400 Wh
Electric bicycle
🚛
Tesla Semi
800V Li-ion pack
100 kWh / 125 Ah
Electric truck
📊 Battery Capacity Reference Guide
Application Typical Capacity Voltage Energy (Wh) Battery Type
AA Battery 2500 mAh 1.5V 3.75 Wh Alkaline
AAA Battery 1200 mAh 1.5V 1.8 Wh Alkaline
9V Battery 550 mAh 9V 4.95 Wh Alkaline
Smartphone 2000-5000 mAh 3.7V 7.4-18.5 Wh Li-ion
Tablet 6000-10000 mAh 3.7V 22-37 Wh Li-polymer
Laptop 45-100 Wh 11.1V 4-9 Ah Li-ion
Power Tool 2-6 Ah 18-20V 36-120 Wh Li-ion
Car (Starter) 45-100 Ah 12V 540-1200 Wh Lead-acid
Solar Storage 100-400 Ah 12/24/48V 1.2-19.2 kWh LiFePO4
Electric Car 40-100 kWh 300-800V 100-250 Ah Li-ion
Grid Storage 1-100 MWh 1000V+ Variable Various

🔋 Battery Capacity Information

  • mAh vs Ah: 1000 mAh = 1 Ah
  • Wh calculation: Wh = Ah × Voltage
  • C-rate: 1C = discharge at 1× capacity (1 hour)
  • Cycle life: Number of charge/discharge cycles
  • Energy density: Wh per kg or volume
  • Self-discharge: Capacity loss when not in use
📚 Battery Capacity Guide

🎯 What is Battery Capacity?

Battery capacity measures how much electrical charge a battery can store and deliver. It's expressed in ampere-hours (Ah) for current capacity or watt-hours (Wh) for energy capacity.

🔬 Conversion Formulas

  • Ah to mAh: mAh = Ah × 1000
  • Ah to Wh: Wh = Ah × Voltage
  • Wh to kWh: kWh = Wh ÷ 1000
  • mWh to Wh: Wh = mWh ÷ 1000
  • Energy to Charge: Charge = Energy ÷ Voltage
  • Runtime: Hours = Capacity ÷ Load Current

🔋 Understanding Different Units

  • Ah (Ampere-hour): Amount of current over time (1A for 1 hour)
  • mAh (Milliampere-hour): 1/1000 of an Ah (common for small devices)
  • Wh (Watt-hour): Energy capacity (Ah × Voltage)
  • kWh (Kilowatt-hour): 1000 Wh (used for large batteries)
  • mWh (Milliwatt-hour): 1/1000 of a Wh (very small devices)

⚡ Battery Performance Factors

  • C-Rate: Discharge rate relative to capacity (1C = full discharge in 1 hour)
  • Temperature: Cold reduces capacity, heat reduces lifespan
  • Age: Capacity decreases over time and cycles
  • Load: High current draw reduces effective capacity
  • Depth of Discharge: How much capacity is used per cycle
  • Chemistry: Different types have different characteristics

🔬 Battery Chemistry Comparison

  • Lead-acid: Low cost, heavy, 12V nominal (cars, backup power)
  • Li-ion: High density, 3.6-3.7V, long life (phones, EVs)
  • LiFePO4: Safe, long life, 3.2V, stable (solar, marine)
  • NiMH: Moderate density, 1.2V, eco-friendly (hybrids)
  • Alkaline: Single-use, 1.5V, cheap (disposable devices)
  • Li-polymer: Flexible shape, 3.7V, lightweight (drones, RC)

📊 Calculating Runtime and Power

  • Runtime = Capacity (Ah) ÷ Load Current (A)
  • Power = Voltage (V) × Current (A)
  • Energy = Power (W) × Time (h)
  • Efficiency factor: Multiply by 0.8-0.9 for real-world
  • Peukert effect: Higher currents reduce effective capacity

🔧 Practical Applications

  • Device Selection: Match battery capacity to usage time
  • Solar Systems: Size battery bank for daily energy needs
  • Electric Vehicles: Range estimation from kWh capacity
  • Backup Power: Calculate runtime for critical loads
  • Portable Devices: Compare mAh ratings for battery life

🔍 Important Considerations

  • Nominal vs Actual: Real capacity often lower than rated
  • Temperature effects: Cold weather can reduce capacity 20-50%
  • Age degradation: Capacity decreases 10-20% per year
  • Discharge rate: Fast discharge reduces effective capacity
  • Voltage matters: Higher voltage = more energy for same Ah
  • Safety limits: Never fully discharge some battery types

💡 Using This Calculator Effectively

  • Always enter the correct voltage for accurate Wh calculations
  • Use nominal voltage (3.7V for Li-ion, 12V for car batteries)
  • Consider real-world efficiency (multiply by 0.8-0.9)
  • Compare batteries using Wh rather than just Ah
  • Factor in temperature and age for practical calculations
  • Use C-rate information for performance estimation