mAh full form is milli Ampere hour, which means how much amperes of current a battery can deliver in an hour time. The battery mAh capacity rating refers to the storage capacity available for a particular battery especially for rechargeable batteries. For example battery with a capacity rating of 1800 mAh could deliver a current of 1800mA for one hour.
Higher mAh ratings for the same battery type will generally mean longer run times. This does not apply when comparing different types of batteries. This means that you may not be able to predict how long your electronic device will run just by looking at the capacity rating of a battery.
mAh Meaning – what is an amp hour
mAh or milli ampere hour is a unit of measure for the electrical battery power over time, generally used to describe also the amount of energy a battery can store. To be more specific, a higher mAh means that a fully-charged battery can power up a device that consumes more energy than another or that it can have a longer lifetime before it needs to be recharged. For example, a battery rated at 2500 mAh can power a device drawing 100 milliamps for 25 hours or 250 milliampere for 10 hours.
mAh Significance in Alkaline Batteries
When powering high drain electronic devices like digital cameras, computer peripherals, or portable music players, an alkaline battery will only deliver a small fraction of its rated capacity in mAh or amp hour. For example AA alkaline batteries typically have a capacity rating of over 2,500 mAh and AA NiMH batteries have rated capacities of only 1,200 to 2,000 mAh. But when it comes to actually powering an electronic device like a digital camera, the NiMH batteries will often run the device for three or four times a long.
Battery mAh in Different Types of Batteries
Even comparing the capacity ratings of similar types of batteries won’t often work since different manufacturers can measure battery capacity in slightly different ways. A NiMH or NiCd battery is likely to deliver much closer to its rated capacity when it’s powering high drain devices. Alkaline batteries have a high rated capacity, but they can only deliver their full capacity if the power is used slowly. This means that a NiMH battery with a rated capacity of 1200 mAh can take many more photos than an alkaline battery with a rated capacity of 2,800.
How to Calculate Battery Life in amp hour
We’ve already said thatbattery life is calculated based on the current rating in milli ampere hour (mAh), but how can battery ampere be exactly calculated?
Well, battery capacity is calculated taking into accounttwo different variables:
- the current rating in milliamp hour
- the load current of the circuit.
So battery life will be high when load current is less, and vice versa. Therefore below is the formula to calculate battery life in hours.
Battery life = Battery capacity in mAh / Load current in mAh
In this way, in addition to knowing the measure of battery voltage, you can also know how long the charged battery will last. For example, if we talk about a circuit connected with 600 mAh current rating and related to the load of 30 mAh, we can calculate that the battery will last roughly for 20 hours.
The calculation is simple and it can be done by everyone, obviously knowing the two reference measurements.
How to Calculate mAh of Battery
Once given the correct definition of mAh, it’s important to understand how to measure the milliampere hour.
You can measure this value by using a multimeter, a load-bearing resistor and a stopwatch to measure elapsed time.
The steps of this operation are quite simple but require great precision and attention.
- If you want to test a lithium-ion battery, you must first recharge it completely.
- Then you have to turn on the digital multimeter and set the measuring dial to the DC (Direct Current) setting – usually indicated by the capital letter “A”.
- After this make sure to connect properly the multimeter to the battery. Check the reading of the current on the multimeter screen, note it down on the sheet of paper and activate the stopwatch.
- Then you just have to wait and turn off the timer when the battery is completely discharged, you can calculate the time in hours required to drain it. At this point you will only have to multiply current rating by the time to measure the battery capacity in milli ampere hours.