Lest you get too excited about possible implications of the title, I’m only addressing the batteries in your latest portable electronic toys. Since many devices no longer have user replaceable batteries, a failed battery is no longer a trivial expense. Replacement may mean bringing or mailing the failed unit to the manufacturer’s repair depot, which replaces the entire device with a factory refurbished litter mate – at costs ranging from $99 (iPad) to $470 (Surface Pro) and delays of up to 6 weeks. Many dejected owners opt to discard the entire unit and replace it with a newer model.
Almost all portable personal electronic devices are now equipped with lithium ion batteries, currently the fastest growing and most promising battery chemistry. While these batteries are lightweight, powerful, reliable and long lived, improper management can significantly shorten their life span.
While older technology NiMH (Nickel Metal Hydride) and NiCad (Nickel Cadmium) batteries had a “memory effect” and had to be completely discharged from 100% to 0% repeatedly to maintain their capacity, lithium ion batteries have no such memory effect. They are managed by a battery charge state monitor – a small computer that handles the whole charging process to make sure the batteries charge as quickly and fully as possible. Completely discharging a Li-ion battery or fully charging it to 100% decreases longevity. Partial discharges are preferable — discharge the battery to something like 40 – 70% before recharging it. Strive to rarely permit your battery to dip below 20%.
While lithium-ion batteries shouldn’t be fully discharged regularly, most modern batteries are “smart batteries” that predict the remaining usable time before recharging is needed. This feature can become inaccurate after repeated shallow discharges. Manufacturers do recommend fully discharging your battery once every month or two to ensure accuracy.
Lithium ion batteries generate heat while in use, especially when fully charged, and are damaged by heat even if the device is turned off. Storing in a confined, warm space (in, a suitcase, an automobile on a sunny Arizona day or even your pants pocket) can start a chain reaction, causing enough heat to start a fire – or explode! Aftermarket replacement batteries are particularly prone to catastrophic failure. Note that airlines have strict limitations on size and quantities of Li-ion batteries carried by passengers. Simply storing charged devices at 40% in an open space at a comfortable temperature is a sufficient precaution.
Lithium ion batteries can be left unused for much longer than other battery types. However, all batteries do self-discharge over time. An unused Li-ion battery will gradually loose its charge over time – about 25% as fast as nickel-cadmium batteries. Some capacity deterioration is already noticeable after one year. Li-ion batteries frequently fail after two or three years, whether your battery is in use – or not. The design and technology is constantly improving; there are Li-ion batteries still in service at 5 years of use.
Want even more information? Visit batteryuniversity.com for detailed tutorials.