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What is mAh (Milliamp Hour): Understanding the Battery Capacity

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Electricity is something we take for granted in the modern world, but it is a powerful force of nature that has been harnessed over the past two centuries for human progress. When we flip a switch or plug in a device, we are completing an electrical circuit that allows electrons to flow and release energy.


Within all matter, atoms contain positively charged protons in their nucleus orbited by negatively charged electrons. Electricity refers to the movement of these electrons between atoms. Metals like copper have loosely bonded outer electrons that can break free and travel through the material, creating an electric current.

Batteries are electrochemical devices that convert chemical energy into electrical energy. They contain two terminals, an anode (-) and cathode (+), separated by an electrolyte solution or barrier. When a battery is connected in a circuit, chemical reactions occur that release electrons on the anode to flow to the cathode, generating an electric current.

Rechargeable batteries can reverse this process by applying an external voltage that forces electrons to flow back into the anode. This restores the chemical state so the battery can provide electricity again in the future. Some of the most common battery types today are lithium-ion and lead-acid batteries. Knowing how batteries function helps appreciate technical terms like milliamp hours.

What is a Milliamp (mA)?

A milliamp (mA) is a unit that measures electric current. An amp (A) is a measure of electric current, defined as 1 coulomb of charge passing through a conductor in 1 second. A milliamp is one thousandth (1/1000) of an amp.

To break this down:

  • An amp (A) is the base unit of electric current
  • A coulomb is a measure of electric charge
  • Electric current flows when electric charges move through a conductor like a wire
  • 1 amp = 1 coulomb of charge flowing per second

So a milliamp (mA) is just one thousandth of that amount of current flow. Some more key things about milliamps:

  • Milliamps are commonly used to measure small amounts of electric current
  • Mobile phone chargers, batteries, and other small electronics use currents measured in mA
  • Typical smartphone chargers provide 1 to 2 amps (1000 to 2000mA) of power
  • Milliamps give an idea of how much electric power a device uses or can deliver over time

In summary, a milliamp is a small unit of electric current, defined as 1/1000 of an amp. Milliamps are useful for measuring the current usage and capacity of batteries, mobile devices, and other low-power electronics. The milliamp is crucial for understanding battery capacities and electricity demands.

What is an Hour (h)?

An hour (h) is a unit of time equal to 60 minutes or 3,600 seconds. It is commonly used to measure battery life, as batteries will discharge over time when powering devices.

The "h" in mAh stands for "hour", referring to the duration over which the battery can supply a certain amount of current (in milliamps). Specifically, it is the amount of current (in milliamps) that a battery can continuously supply for one hour before becoming completely discharged.

So in simple terms, mAh relates to how long a battery would last if it was supplying a constant amount of current. The higher the mAh rating, the longer it can supply power before needing to be recharged. Knowing the mAh capacity helps estimate the battery life for your device or application.

What is Milliamp Hour (mAh)?

Milliamp hour (mAh) is a unit of measure used to indicate the energy capacity of a battery. It refers to how much current a battery can provide over time.

The milliamp hour rating is calculated by multiplying the discharge current (in milliamps) by the discharge time (in hours). For example, if a battery can provide 350mA for 5 hours before being depleted, its capacity would be:

350mA x 5h = 1,750mAh

So the higher the mAh rating, the longer that battery can deliver power before it needs to be recharged. It's an important specification to look for when comparing batteries or battery-powered devices.

The mAh capacity indicates how much energy is stored in the battery. A battery with a capacity of 500mAh can deliver 500mA for one hour, or 50mA for 10 hours, and so on - until the stored energy is depleted. The mAh rating is like the size of the "gas tank" on the battery.

Milliamps (mA) are 1/1000 of an amp. So a milliamp is a very small unit of electrical current. The "hour" part refers to the discharge time. Together, the milliamp hour rating tells you the battery's overall energy storage potential per charge cycle.

Significance of mAh

The milliamp hour rating is significant because it indicates the capacity and lifetime of a battery before it needs recharging. The higher the mAh, the more energy the battery can deliver over time. This makes mAh one of the key specifications to consider when purchasing any battery-powered device.

For mobile devices like phones and laptops, a higher mAh directly translates to longer battery life between charges. A phone with 3000 mAh will last much longer than one with 2000 mAh when performing the same tasks. For products like power banks, a higher mAh means the power bank can recharge your devices more times before needing to be recharged itself.

The mAh capacity is crucial for electric vehicles too. The larger the battery (higher mAh), the greater the driving range possible from a single charge. For example, a Tesla Model S with a 100 kWh battery can drive over 300 miles on a charge, while the lower capacity car with a 30 kWh battery may only get 100 miles.

When looking at any rechargeable battery, whether for small consumer devices or large power systems, the mAh rating gives an accurate estimate of how much total energy can be supplied over the lifetime of the battery. Maximizing mAh is essential for longer run times and less frequent recharging.

mAh vs Charge Capacity

The mAh rating of a battery is different from its total charge capacity. While they are related, these specifications measure different things.

The mAh rating indicates how much current a battery can deliver over time. Specifically, it is the amount of milliamps that can be supplied for 1 hour before the battery is depleted. A higher mAh rating means the battery can supply more current for a longer duration before needing to be recharged.

However, the total charge capacity indicates the battery's overall energy storage. This is measured in watt-hours (Wh) rather than current over time. The charge capacity depends on the battery's voltage in addition to its mAh rating. To find the charge capacity, you would multiply the voltage by the mAh rating.

For example, a 12V battery rated at 100Ah would have a charge capacity of 1200Wh (12V x 100Ah). Meanwhile, a 3.7V battery rated at 3000mAh would have a charge capacity of only 11.1Wh (3.7V x 3000mAh).

So while the 3.7V battery has a higher mAh, the 12V battery can actually store much more total energy. The mAh rating alone does not reveal the full charge capacity. It only specifies how much current can be supplied each hour, not the total energy.

In summary, mAh relates to continuous current over time, while charge capacity in Wh relates to total stored energy. Both specifications are important for understanding a battery's capabilities and limitations.

mAh for Mobile Batteries

When looking at batteries for mobile devices like smartphones and tablets, the mAh rating is especially important. This determines how long your phone or tablet can run before needing to be recharged.

Higher mAh ratings mean longer battery life. For example, most modern smartphone batteries range from 3000-5000 mAh. Flagship models tend to be on the higher end, normally they are with a 5000 mAh battery. This translates to over a full day of average use before needing to be plugged in.

Tablets with their larger bodies can accommodate batteries with mAh ratings of 7000 to 10,000 for all-day endurance. The latest iPad Pro 12.9" packs a giant 11,664 mAh battery for up to 10 hours of continuous use.

Of course, the actual battery runtime depends on factors like screen brightness, processor load, and background apps. But in general, higher mAh mobile batteries last longer. So when shopping for a new phone or tablet, take note of the mAh rating along with other specs.

mAh for Car Batteries

When looking at car batteries, the mAh rating is crucial. Most car batteries have ratings between 35-120Ah. This number determines how many milliamps it can supply for 1 hour before being depleted.

For example, a 60Ah car battery could supply 60 amps for 1 hour or 30 amps for 2 hours before needing to be recharged by the alternator. The higher the Ah rating, the greater the reserve capacity and overall power the battery can supply.

Cold Cranking Amps (CCA) is another important metric for car batteries related to high current draw needed to start an engine in cold weather. But the Ah rating determines overall energy storage and run time capacity once the engine is running.

Higher Ah car batteries can run vehicle electronics and accessories for longer if the engine is off. However, the tradeoff is they tend to be larger and heavier than lower Ah models. When your car battery is showing its age, choosing a replacement with a higher Ah rating will provide more reliable starts and power reserves.

mAh for Rechargeable Batteries

Rechargeable batteries come in many sizes and capacities. Two of the most common rechargeable battery sizes for consumer devices are AA and AAA.

AA and AAA rechargeable batteries typically range from 500 mAh to 3000 mAh capacity. Lower capacity batteries around 500-1000 mAh are cheaper but don't last as long per charge. Higher capacity batteries around 2000-3000 mAh cost more but provide longer runtime.

mAh for Rechargeable Batteries

For example, a common AA NiMH rechargeable battery has 2500 mAh capacity. This means it can provide a current of 2500 milliamps for 1 hour, if discharged at a rate of 1 amp. Or it could provide 500 milliamps for 5 hours at a lower 0.2 amp discharge rate. The mAh rating is useful for estimating how long a rechargeable battery can last depending on your power needs.

Higher mAh AA/AAA batteries are recommended for high drain devices like flashlights, toys and wireless electronics. Lower mAh batteries are suitable for low power devices like clocks and remote controls. When shopping for rechargeables, read the label for the mAh rating to compare battery life.

Aim for batteries with at least 2000+ mAh for AA and 1000+ mAh for AAA. Investing in good rechargeable batteries with high mAh ratings can save money in the long run compared to disposables.

How to Convert mAh to Watt Hours?

The milliamp hour (mAh) rating is a measure of electric charge, whereas watt hours (Wh) is a measure of energy. We can convert between these units using a simple formula:

Wh = mAh x Voltage / 1000

For example, if a 12V battery has a 5000mAh capacity:

  • mAh = 5000
  • Voltage = 12V
  • Therefore:
  • Wh = 5000 x 12 / 1000
  • Wh = 60

So a 5000mAh 12V battery stores 60 watt hours of energy.

In simple terms, if you know the voltage of a battery, you can calculate how many watt hours it can provide from its milliamp hour rating. This conversion helps compare batteries of different voltages using a standard unit of energy.

The mAh to Wh formula is useful when sizing batteries and solar systems. Watt hours represent actual energy storage, whereas mAh does not account for voltage. Converting mAh to Wh makes it easier to calculate how many watts a battery can deliver over time.

Top Growatt Battery With Best Storage Capacity

When it comes to high capacity home battery storage, Growatt offers some of the top solutions on the market right now. Here are a few of their flagship products with exceptional milliamp hour ratings:

Growatt INFINITY 2000 + Extra Batteries


Growatt INFINITY 2000 + Extra Batteries

The Growatt INFINITY 2000 + Extra Batteries offers max 6144Wh of capacity. With a max 2300W input, it easily charging in 1.5Hrs to 100%.

This is one of Growatt's most popular solar generator bundles for whole home backup at an affordable price point compared to competitors. The modular architecture lets you start small and add more capacity as needed.

With their cutting edge designs leveraging large format LiFePO4 battery cells, Growatt is a leader in renewable energy storage and high capacity power stations. Their batteries offer some of the highest mAh ratings in the industry.

mAh Importance for Solar Storage

High mAh is critical for effective solar energy storage. Since solar panels only produce energy when the sun is shining, batteries are needed to store excess electricity for use at night or on cloudy days. The higher the battery's mAh rating, the more solar energy it can hold, and the longer it can power devices when solar panels aren't actively charging.

For off-grid solar applications like RVs, boats, and remote cabins, mAh capacity directly affects how many hours or days you can go without sunlight before needing to recharge. A battery bank's mAh rating also determines the types of appliances and devices it can handle. Running high-draw equipment like AC units requires a battery with ample mAh capacity to avoid quickly draining the battery.

When designing a solar power system, calculating the average daily power usage is crucial for determining the minimum mAh needed for reliable off-grid operation. Insufficient mAh capacity leads to the battery draining too quickly, while overly high mAh ratings add cost without much added benefit. Finding the optimal balance for your specific needs ensures your solar batteries can store enough surplus solar energy to bridge time periods when sunlight is unavailable.

Comparing mAh Between Devices

You can't directly compare the mAh ratings between batteries of different types. For example, the mAh rating of a lithium-ion battery doesn't equate to the same amount of power as the mAh rating of a lead-acid battery.

This is because mAh is a measure of charge capacity, but the voltages differ between battery chemistries. A lithium-ion battery operates at around 3.7 volts while a lead-acid battery is around 2 volts. So a lithium-ion battery stores more energy at the same mAh rating compared to a lead-acid battery.

Additionally, the discharge characteristics differ between battery types which affects usable capacity. Lithium-ion batteries maintain voltage consistently as they deplete. But lead-acid batteries slowly drop in voltage during discharge, so the usable capacity is less than the stated mAh rating.

You can only directly compare mAh figures when looking at batteries of the same chemistry and voltage. For example, comparing two 12V lead-acid batteries or two 3.7V lithium-ion batteries. But you need to factor in the battery voltages when comparing lithium-ion and lead-acid mAh ratings.

In summary, mAh measures charge capacity but higher voltage batteries store more energy at the same mAh rating. Only directly compare mAh between identical battery types.

Does Higher mAh Always Mean Better? - mAh vs Battery Life Span

The milliamp hour (mAh) rating of a battery indicates its energy storage capacity, but it does not directly correlate to battery lifespan. In other words, a higher mAh does not necessarily mean the battery will last longer. There are several other factors that determine overall battery life.

Construction Quality

How the battery is constructed plays a major role in cycle life. Premium grade materials, tightly controlled manufacturing, and rigorous testing generally lead to batteries that can handle more charge/discharge cycles before degrading. Mass produced low-cost batteries tend to have lower quality and shorter overall lifespan.

Proper Usage

The way a battery is charged, discharged, and maintained significantly impacts its usable life. Best practices like avoiding full discharges, operating within the safe voltage range, charging to only 80-90% capacity, and storing at 40-50% charge can enable batteries to last for years. Poor usage habits can quickly degrade batteries.

Charging Method

Advanced charging systems that precisely control voltage, current, and temperature can maximize cycle count. Simple chargers without these protections can cause early battery failure. Smart BMS battery management systems help extend life through monitoring and protection.

Chemistry & Design

New battery chemistries like lithium-ion inherently last longer than older lead acid batteries when designed well. But the electrode materials, electrolytes, separators, form factor, and other engineering choices also affect durability. Well engineered designs optimize all these factors.

So in summary, higher mAh capacity alone does not guarantee longer battery lifespan. Proper construction, charging, usage and advanced engineering play pivotal roles in enabling batteries to achieve their maximum cycle life potential. When evaluating batteries, all these aspects should be considered along with mAh ratings.


Understanding milliamp hours (mAh) is crucial when evaluating batteries and battery-powered devices. As we've explored, mAh is a measurement of a battery's storage capacity and estimated runtime before needing to be recharged. It indicates how much current a battery can deliver over a period of time.

What is mAh (Milliamp Hour)

Understanding milliamp hours is key to choosing the right battery for your needs and properly leveraging battery capacity. With the prominence of mobile electronics and electric mobility, mAh will only grow more significant in years to come.

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