Well, if you want to be pedantic about proper unit abbreviations, then "mah" doesn't mean anything. But "mAh" with a capital A is an abbreviation for "milliampere hour." This is a unit of electric charge , and it's the most common way to express the capacity of small batteries. (Bigger batteries are labeled in ampere hours; 1 Ah = 1000 mAh.) You can calculate the capacity of a battery by multiplying the discharge current by the duration of time that the battery can supply that much current.

Very roughly , a 1000 mAh battery can supply 1000 mAh for one hour, or 100 mAh for ten hours, or 10 mAh for 100 hours, but this is a simplification since the capacity of the battery depends on the discharge rate. (How much it changes depends on the type of battery.) So a rating of 1000 mAh is actually an incomplete description of the battery's capacity for a phone unless you also know the corresponding discharge rate.

Ampere
It’s a battery health app that detects the charge and discharge rate for an Android device. It will also give you an overview of your battery and for a small price you can disable the in-app ads and at the same time unlock the notification bar feature. The app does not require your device to be rooted.

Install Ampere and launch it. It takes ten seconds to detect the information for your device. The information you get tells you the current temperature of your device, the voltage input it’s getting from the power source and the number of mA (milliamps) it is receiving or losing.

It can also detect if the device is charging too fast or too slowly which helps determine if something is wrong with your data cable or if the device isn’t getting enough charge from a wall socket or a laptop.





The app’s pro version adds a customizable notification that tells you the current state of the charge or discharge when you pull down the notification bar. Before you install the app read it’s description where the developers have provided a list of known devices that it doesn’t work on due to hardware limitations. Ampere requires Android 4.3 and above.
Install Ampere From The Google Play Store

are u sure it works or gives the right information because all this so called battery saver or app that has to do with battery stuffs are hoax