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What exactly does mAh rating means? I know that it means the milliamperes supplied by the battery in one hour but i need a more conceptual and practical definition/example.

How does mAh rating tell the current supplied to the load? How does it vary with the load specification.

Also, suppose a mobile phone's battery has 3000mAh, if i supply it with 1000mA, then does it mean that the battery will be fully charged in 3 hours?

And will a 3000 mAh battery deliver a current of 3000mA for 1 hour to a load? Will this rating degrade in a practical scenario. Please explain.

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    \$\begingroup\$ It measures the same type of thing as the capacity of a bottle of milk. It tells you nothing about how many cups of tea you can make with that bottle, or how long it would take to pour into cups. \$\endgroup\$ – Sean Houlihane Oct 21 '16 at 13:11
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    \$\begingroup\$ read-up: batteryuniversity.com first and foremost. Then this, this, this. Then read the datasheet for your battery. \$\endgroup\$ – Nick Alexeev Oct 21 '16 at 13:12
  • \$\begingroup\$ Slight change in grammar: "it means the milliamperes supplied by the battery for one hour". It's not mA/h but mA * h. That's an important point. 3000mAh = 3000mA * 1h = 1500mA * 2h = 1000mA * 3h = ... It's just capacity, like the volume of a bottle. A larger bottle's content will last longer than a smaller bottle's if consumed at the same rate. There's nothing more to the raw mAh number. \$\endgroup\$ – JimmyB Oct 21 '16 at 14:31
  • \$\begingroup\$ In fact, mAh is a redundant 'artificial' composed unit denoting an amount of charge. The physical unit is Coulomb with 1C = 1A * 1s = 1000mAs = (1000/3600)mAh ~ 0.28mAh, which equals about 6x10^18 electrons. \$\endgroup\$ – JimmyB Oct 21 '16 at 14:36
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What exactly does mAh rating means?

The mAh rating indicates the capacity of the battery in current (mA) and time (h). This means that a 3000 mAh battery should be able to supply 3000 mA during one hour. But there is more. It might be that the battery is only able to supply 1500 mA /h. This is indicated in the C value mentioned on the battery or at least in the datasheet. There is also a C value for chargeing the battery. All this information can be found in the datasheet.

How does mAh rating tell the current supplied to the load? How does it vary with the load specification.

The mAh rating tells nothing about the current supplied to the load. The design of the load determines the maximum current that will be drawn from a battery. Again our example. If the C=1 and the load takes less then 3000 mA then you can use the battery without any problem. If the actual load from the application is 2000 mA then you could use the battery in theory 1.5 h. If the load takes more then 3000 mA then your battery is overloaded and will get damaged.

Also, suppose a mobile phone's battery has 3000mAh, if i supply it with 1000mA, then does it mean that the battery will be fully charged in 3 hours?

If that was true it would be nice but there are always losses involved. So in practice you need more time. How much more depend on the (remaining) quality of the battery.

And will a 3000 mAh battery deliver a current of 3000mA for 1 hour to a load?

If that was true it also would be nice. But at the end of a discharge the voltage of a battery drops and might become to low. Modern LIPO batteries also don't like to be discharged completely. So the discharge time available is less then the basis calculation.

If you treat your batteries well you will stay more close to the theoretical capacity. Mistreating reduces the capacity heavely. Temperature also plays an important role. That is why cars have starting problems in the winter.

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The mAh rating is, theoretically, how many hours the battery will last running continually at a 1mA current draw. Theory and practice are quite different, and the differences are nuanced. There is really no one size fits all answer to how the metric extrapolates in different scenarios, and at a minimum, each battery chemistry had its own set of caveats and rules of thumb.

If you look at it dimensionally, Amps are Coulombs of charge per second. When you multiply it by time, you end up with Coulombs of charge, which is the chemical capacity of the battery.

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mAh is a measure of electric charge. It is the product of current and time.

It has nothing to do with the instantaneous current you can draw, it is a measure of the total electrical charge you can draw before the battery is flat.

In partial scenarios batteries will have different milliamp hour ratings for different current loads, and the only way to achieve their nameplate charge capacity is if you have a certain load at a certain temperature..

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quantity/time \$\rightarrow\$ derivative ("speed")

(quantity/time)*time \$\rightarrow\$ integral ("area")

1 mAh = \$10^{-3} \frac{C}{s}3600s\$ =3.6 C

More details here:

Area under voltage vs time discharge curve

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