“AH” on a battery stands for Ampere-hour, which is a unit of electric charge. It represents the capacity of a battery and is commonly used to describe the amount of energy a battery can store and deliver over time.

However, to fully understand a battery’s capacity to power devices, it’s important to also consider the Watt-hour (Wh) measurement, which factors in the battery’s voltage.

**Ampere-hour**(Ah) measures the charge capacity of a battery, indicating how long it can deliver a specific current (e.g., a 100 Ah battery can provide 100 amperes for one hour).**Watt-hour**(Wh) provides a comprehensive measure of a battery’s total energy capacity, calculated by multiplying the Ah rating by the battery’s voltage (e.g., a 12V battery with 100 Ah has 1200 Wh of energy).**Practical Application**: While Ah indicates the duration a battery can deliver power, Wh is a more accurate indicator of the total energy available, considering both voltage and capacity, crucial for determining how long a battery can power devices.

Here is an analogy that can help you better understand it:

**Voltage (Volts)**is like the engine power of a car, determining the strength of the electrical current.**Ampere-hours (Ah)**is comparable to the size of the car’s fuel tank, indicating how long the battery can last.**Watt-hours (Wh)**represents the total driving range, combining the aspects of both engine power and fuel capacity to indicate the total energy output of the battery.

Total Battery Capacity = Voltage * Capacity

Here’s a more comprehensive breakdown:

**Ampere-hour (AH)**: This unit measures the battery’s ability to provide one ampere (A) of current for one hour.**Capacity Indicator**: The AH rating indicates how much current a battery can supply for a specific period. For example, a 100 AH battery can theoretically deliver 100 amperes for one hour, or 1 ampere for 100 hours.**Usage in Batteries**: It’s a standard measure for batteries of all types, including car batteries, deep-cycle batteries, and small batteries in electronic devices.

## Capacity (Ah) Isn’t the Full Story

The capacity of a battery to power devices for a particular duration depends on both its Ampere-hour (Ah) rating and its voltage (V).

The Watt-hour (Wh) measurement, which is the product of voltage and Ampere-hours, provides a more comprehensive understanding of a battery’s total energy capacity. Here’s a refined explanation:

**Watt-hour (Wh)**: This unit measures the total energy capacity of a battery. It is calculated by multiplying the Ampere-hour (Ah) rating by the voltage (V) of the battery.**Understanding Capacity**: While the Ah rating indicates the charge capacity, the Wh rating gives a complete picture of how much energy the battery can store and deliver. For example, a 12V battery with a 100Ah rating has 1200Wh of energy (12V x 100Ah).**Comparing Batteries**: When comparing batteries, looking at the Wh rating is more accurate for understanding how long a battery can power devices, as it takes into account both the voltage and the Ah rating.**Practical Usage**: A higher Wh rating generally means that a battery can store more energy, thus potentially powering devices for a longer period.**Device Requirements**: The suitability of a battery for a particular application depends on the energy requirements of the devices it needs to power, which are often measured in watts.

In summary, while the Ah rating is important, the Wh rating is a more comprehensive measure of a battery’s total energy capacity, considering both the charge it can hold and the voltage at which it operates.

## FAQ

### Is a higher Ah battery better?

Generally yes. But it goes together with voltage. Let me explain.

If you have four 12V, 100Ah lithium batteries and configure them in a 12V 400Ah battery with a 3,000W inverter, you will draw a current of 250amps!

Now, if you take the same battery and configure it to 24V 200Ah, then you will have 125Amps, which is much better.

Your wires will be less thick, saving you a lot of money.

### How long will a 100Ah battery last?

It depends on the chemistry of the battery. For lead acid this will be 2.5 hours. Because the c-rate is 0.2C and you can only discharge a lead-acid battery to 50% to not damage the battery. The formula: 100Ah*0.2C= 20Amps for 5 hours. Because it’s only half, it’s 20Amps for 2.5hours, or 10 amps for 5 hours, and so on.

### What is mAh?

1 Ah = 1,000mAh

mAh or milli ampére hour is just 1,000 times smaller than Ah. On small batteries like AA batteries you will see 3,000mAh, this is the same as 3Ah.

### Is Ah always the same?

No, if the battery gets discharged quickly (more than the recommended C-rate, heat will generate, and the capacity of the battery will reduce.

### Does a higher ah battery give more power?

No, a higher Ah value doesn’t give you more power.

For example, a 12V 400Ah battery holds 4,800Wh. A 48V 100Ah battery holds 4,800Wh too.

These two batteries are completely different but have the same power contents.

Read more: LiFePO4 voltage chart

I’m an off-grid enthusiast. I created this website to give clear and straight-to-the-point advice about solar power. I’m also the author of the book ‘Off-grid solar power simplified‘. Read more about me on my about page, check out my Youtube channel, or send me a message.