What Is An Amp Hour? – Watt & Watt-Hour: Terminology Guide In 2023

What Is An Amp Hour

Understanding an amp hour is very important when you are checking the battery life. Even most of the people did not know what an amp hour is. If you are also that person, let me clear your confusion by giving the best information in this blog about what is an amp hour.

An amp hour is the rating used to tell the consumers how much the amp car battery provides for an hour. It all depends on the battery size. However, generally, the C/5 battery provides 26.8 amp hours which means its duration will be 5 hours.

For instance, the same battery could provide 36 amp hours of power for 100 hours. But how do you understand what an amp hour is? Including;

  1. Understanding the amp rating
  2. Why it is important to checking
  3. How to check an amp hour
  4. How long is the amp hour long?

Continue reading to know about more;

What Is The Meaning Of Ampere Hour In Battery?

meaning of Ampere hour in battery
Source: Haynes

The Ampere hour or amp hour is a unit of measurement for electrical charge, used especially for batteries. However, The amp hour is the capacity of a battery when discharging at the rate of one ampere for one hour.

For example, a battery that discharges one ampere per hour has an amp hour rating of one ampere-hour. Besides, the battery capacity can give the amount of energy the battery can deliver over a while.

The watt-hour is the SI-derived unit of electrical energy. In other words, it is the energy released by a system that delivers one watt of energy per unit of time.

What Is An Amp Hour And Why It Is Important To Check?

An amp hour is a unit of measurement. It defines the amount of current that a battery can output in one hour, given a constant voltage of one volt. It’s important to understand the amp hour rating of a battery as it tells you how long you can use a device before you need to recharge it.

If you don’t check it before driving or traveling, your car will not survive long-distance if the battery falls. An amp hour rating lets consumers know how much power a battery can have for exactly one hour.

It depends on the size; however, on the standard AA size of the battery, the amp hour rating usually gives milliamp hours (mAh).

Consequently, large batteries provide the rating as Ah. However, as technology far, there are many types of car batteries available in the market. One of the cycle batteries will provide the Ah rating with multiple C ratings.

It means that your battery provides you with a specific time. As an example, 26.8 amp hours can be obtained safely from a battery at C/5. In other words, it supplies 26.8 amps in 5 hours without going down.

In this way, a 36 amp hour battery can provide power for 100 hours. You just need to choose the battery you need daily or weekly to compare it to the amp hours for the C ratings.

But, if you are not sure how to compare the C ratings to how to compare and use them, you should choose the C/20 because it is the middle ground and gives a sense of battery performance in general.

How Long Will A 100 Amp Hour Battery Last?

The power consumption of a 12 volt, 1.2 watts LED light is 0.1 amps since 1.2 watts / 12 volts equals 0.1 amps. So a battery with 100ah (amp hours) will last 1000 hours.

How Many AH Is A 12v Car Battery?

AH is a 12v car battery
Source: ups battery center

As I mentioned above, car batteries can use a capacity of 48 hours. However, the average rating of the amp is a 12 volt car battery which is fully charged at the rate of 48 amp hours.

It means that it can deliver 1 amp for 48 hours and 2 amps for 24 hours. So it all depends on you, how long the car battery does you need. If you need to travel so far, you will need the 1 amp to deliver the capacity for 48 hours.

How Do You Calculate Amps Per Hour?

If your maths calculation is not too good, you may face difficulty in calculating car physics. But in this blog, as I have covered all the necessary questions and knowledge about car battery amp, I will also discuss how you calculate amps per hour?

So, it is the key to using the watts you may know to calculate the car battery voltage amps. The key is to use the watts you know to calculate the amps at the battery voltage.

Take the example of running a 250 watt 110VAC light bulb for 5 hours from an inverter. In 12 volts, amp-hours are equal to watt-hours divided by 12 volts, or 1470 divided by 12 equals 122.5 amp-hours.

How Many Watts is 100 Amp Hours?

100 amp hours in watts
Source: learn metrics

By simply calculating, an AMP hour X voltage is equal to the watt hours. It means that your answer will tell you the amp battery that can sustain the watts for an hour.

Therefore, we can sustain about 1200 watts worth of devices for an hour or 600 watts worth of devices for two hours with our 100 amp battery.


So what is an amp hour? In short, it is a measurement of how much power a battery can hold. In more detail, it is the amount of time a battery can discharge at a certain current level before it runs out of power.

The higher the amp hour rating, the more energy the battery can store. I hope from the above article and this short quotation; you will get many understanding points about the car battery.