Rechargeable batteries have a finite lifespan. Not only do they only provide our mobile devices with a relatively limited uptime to a single charge, but over time and use, so their ability to retain charge deteriorates. This is one of the main advantages of customers picking a device with a replaceable battery, because it means that the old and worn out battery may be simply and easily replaced, rather than return the full device to the manufacturer or using a third party battery replacement service. However, not all batteries are created equal and a recent consumer watchdog survey has compared a number of devices (eight 'phones and six tablets) manufacturers' batteries over a simulated two year period to see what the difference is in retained battery capacity is at the end of the process. The team charged and discharged the batteries 365 times over seven months, working on the assumption that customers would recharge their devices every other day, and the results show that the LG G Flex performed best, with it's 3,500 mAh battery recording just a 3% drop in capacity. At the other side of the scale, the Samsung Galaxy S5's 2,800 mAh (replaceable) battery lost 12% capacity over 365 charges and the iPhone 5S lost 13% of its charge. The discharge process involved streaming a video clip over WiFi with the brightness at maximum, only recharging once the battery capacity reached 20%.
It is perhaps no surprise that LG's battery performs well in this test because the LG business empire includes in-house battery technologies, which have found their way into a few of their handsets. This included the LG Nexus 4, which has a battery designed to retain 85% capacity after 800 charge cycles rather than the more usual industry benchmark of 500 charges.
Whilst there is no normal when it comes to battery life, because we all use our devices individually and as such, show different battery uptimes, there are a number of potential flaws with the source's battery measurement. One is that most people wish to use their battery for a given period of time, such as a day, and will put the device on charge at the end of the evening. In these scenarios, the device with the longer battery life (or the larger capacity battery) would be subjected to somewhat less stress over the course of a year. In the example of the iPhone 5S, this is likely to require a daily recharge whereas the LG G Flex may only need a recharge every other day.
The source report highlighted that the better the retained capacity of a battery over a period of time and use, the lower the risk of a customer disposing of a device. It also noted that many manufacturers provide a shorter warranty on batteries compared with the device; LG, Nokia, Samsung only provide a six month battery warranty but at least a twelve month warranty on the device in question.