When evaluating custom battery chargers, power adapters, and charging stations it’s helpful to be familiar with “battery speak.” Here are a few things to know before powering up.
mAh stands for milliamp hour, and is a unit for measuring electric power over time. It describes the amount of energy a battery can both store and discharge. For example, a 1,000 mAh battery can power a device drawing 100 milliamps for 10 hours. Here’s a real-life example: the iPhone 5S requires about 1,570 mAh for a full charge. A 9,000 mAh portable iPhone charger battery pack could therefore charge an iPhone 5S five times before the pack itself needs recharging.
Often in the description of a battery charger, you’ll come across things like “5V/1.5A” and “5V/2.1A.” These numbers refer to the device you’re charging. The V stands for volts. The A stands for amps (and milliamps). So, for instance, 1.5A means both 1.5 amps and 1500 mAh.
Rechargeable lithium-ion (li-ion) and lithium-polymer (li-polymer) batteries have different capacities. Generally, lithium-ion batteries have less capacity, whereas lithium-polymer batteries allow for a slight increase in energy density.
All electronic devices—obviously—aren’t created equal. This also applies to your device’s energy demands. Smartphones have different appetites from tablets especially when hooked to all the many tablet accessories that exist. To avoid over or undercharging, it’s beneficial to know a device’s capacity needs.
Smaller devices such as audio players and smartphones usually require a charger with a 5V output rating. Larger devices that require a DC power input, such as laptops, may need a charger with an output rating of between 12 and 24V.
Keep in mind, though, that many batteries use a fast charge to get your device up to 80% battery capacity, then switch to what’s called trickle charging. It takes about two hours to charge an iPod to 80%, for instance, then two more hours to fully charge it.
To increase the life span of the batteries in your devices, be mindful of the following:
1. Chargers are often designed for certain battery types. To avoid starting a fire or shorting out the battery, don’t charge a battery in a charger that isn’t specifically approved to work with that battery.
2. Only plug your charger into an outlet when you’re using it. Leaving it continuously plugged in might curtail the life span of your charger and battery.
3. Charging your phone while it’s in certain carrying cases—which are different than phone charging cases—may generate excess heat, which can affect battery capacity. If you notice your phone getting hot when charging, take it out of the case.
We hope that these guidelines provide you with some handy working knowledge to help you understand the sometimes complex terminology related to batteries, their chargers, and your electronic devices.