13 March 2017

Is More mAh Means More Battery Life?

An Milliamp Hour(mAh) is a unit for measuring electric power over time. mAh is commonly used to describe the total amount of energy a battery can store at one time. It's the easiest way to distinguish the strength or capacity of a battery. The higher the mAh, the longer the battery will last. 

A battery rated for more mAh will power a phone for a longer amount of time, given the same usage pattern. The trade-off is that batteries with more mAh are generally also physically larger.


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 mA for one hour, or 100 mA for ten hours, or 10 mA 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 unless you also know the corresponding discharge rate.

The capacity at 500 mA discharge rate is less than half the capacity at 25 mA. At 25 mA, you'd get about 48 hours of continuous service from this battery; at 250 mA the battery would last about 3 hours, and at 500 mA you'd only get about one hour of use.

Here is similar data from a datasheet for an ELK-1280 sealed lead-acid battery. (I have no experience with this manufacturer; I just picked this one at random.) The capacity at a 1-hour discharge rate is a little more than half the capacity at a 20-hour discharge rate. (It's standard for lead-acid batteries to be rated at the 20-hour rate.) As the leftmost column of the table suggests, the capacity also depends on temperature.

Here is another graph for a rechargeable AA battery. The information is presented in a different form, but you can see that the capacity of the NiMH battery does not depend very strongly on discharge rate until you start getting to very high rates. At discharge rates from 230 to 2300 mA, you get very close to 2300 mAh of capacity (that is, the duration of the discharge is very close to what you get by dividing 2300 mAh by the current), but at 4600 mA you get a little less (the duration of the discharge is less than half an hour). 

Incidentally, one mAh is 3.6 coulombs or the charge of approximately 22,500,000,000,000,000,000 electrons.


More is more capacity - your camera will work for longer, with a battery with more mAh.


  • Volts are 'pressure', where Amps are the current (or flowrate). 
  • Pressure washer = high voltage low current. 
  • River flow = very low pressure, very high current. Neither measures capacity directly. 
  • If you take a current over an amount of time, you get a total amount. 
  • The river flows 1000 cubic meters per second. (not a capacity, a flowrate). 
  • In one hour, the river flows 3600 seconds * 1000/second = 3600000 Cubic meters (a capacity). 
  • Same applies here. The battery you mention is 3.7 volts, with .740 amp-hours of storage capacity. 
  • This means it can sustain an output of 3.7 volts, and a current of .74 amps, for an hour, give or take.

Thanks for Reading...

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