The Difference Between Battery Capacity and Charge Cycles
With rechargeable lithium ion batteries so commonplace these days, consumers are taking a more intentional look at battery specs before they buy. Two things they look at are battery capacity and the number of charge cycles a battery offers. To some consumers, these appear to be the same thing. They are not.
It pays to know the difference between the two, so this post will explain the difference in simple terms. If you are shopping for top quality rechargeable lithium-ion batteries, Salt Lake City’s Pale Blue Earth suggests paying close attention to battery capacity versus charge cycles so that you know exactly what you’re getting.
Battery Capacity Explained
Manufactures express battery capacity as milliampere-hours, or mAh. It is a measurement describing the amount of current a battery can deliver consistently for one hour. Thus, a 1mAh battery can consistently deliver 1 mA of current for 60 minutes. It’s a one-to-one ratio by the way, so a 500 mAh battery delivers 500 mAh for 500 hours.
Unfortunately, this static formula is only theoretical. Many different factors determine actual capacity in the real world. For example, how long a lithium-ion battery can deliver consistent power depends on how quickly power is being drawn from it. To figure this out, you need a complicated formula that converts mAh to watts. Then you need to know how much juice a device draws from the battery in watt hours. Once you have that number, you have to convert back to mAh.
To make things as simple as possible, let’s say you have a 1,000 mAh battery powering a device that draws 10 mAh per hour. You will not get 1,000 hours of power between battery charges. Instead, you will only get 100 hours.
Battery Life vs. Charge Cycles
Another way to look at battery capacity is battery life. For example, how long does your cell phone battery last under normal circumstances? If you were to purchase USB batteries from Pale Blue Earth, how long can they power your portable MP3 player on a single charge? In both cases, frequency of use affects battery life.
All things considered, the number of charge cycles you get might be a more important factor. Charge cycles are a more accurate reflection of how much power you will ultimately get out of a set of rechargeable batteries. If capacity is the same, a battery with 1,000 charge cycles ultimately gives you more power than one with just 500.
Charge Cycles Explained
Rechargeable USB batteries have a limited useful life. Every time you charge and discharge them, you take some of the life out of them. At some point they will no longer hold a charge.
A battery rated for 1,000 charge cycles should allow you to charge and discharge it at least 1,000 times. Now you have something a bit more tangible that doesn’t require complicated math to figure out. More charging cycles means a longer usable life. In most cases, it generally means more overall power too.
For the record, charge cycle is generally more important when you’re talking about USB rechargeable batteries. When you’re talking about something like a smartphone with a hardwired battery you cannot change, you don’t have much of a choice anyway.
Next time you shop for lithium-ion batteries of any type, take a look at both capacity and charging cycles. Capacity will be important if you will use those batteries to run something like a power-hungry digital camera. But for less intense needs, charging cycles are a more important factor. Maximize your investment by looking for batteries that offer the most charging cycles.