Both the iPhone 6 and iPhone 6 Plus come with bigger and thinner batteries compared to anything Apple has made before, but that doesn’t necessarily mean all iPhone 6 buyers will be happy with battery life on their devices. That doesn’t change the fact that Apple is trying to maximize battery life in its 2014 iPhones, which should offer better efficiency than any previous models. When tearing down the new iPhones and closely inspecting their internal components, Chipworks made a surprising discovery that appears to be related to better battery life.

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The publication said in its initial teardown that it discovered not one, but two accelerometers inside the iPhone 6, one from InvenSense and one for Bosch, without being able to explain why Apple made this particular choice. A few days later, the publication said it solved the mystery, revealing that battery life concerns led Apple to include the extra chip in the iPhone 6.

InvenSense’s chip is a six-axis accelerometer that’s good for gaming and “other applications that need sophisticated inertial sensing capabilities,” but there’s a downside to that, and that’s increased battery consumption while it’s in use.

Bosch’s three-axis accelerometer operates at a significantly lower power (130 µA in normal mode vs up to 3.4 mA for InvenSense’s), and features a faster start-up time, meaning that the chip will handle most accelerometer-related actions where “full six-axis integration is not required and where lower sensitivity is acceptable.”

“The integration of two accelerometers into the iPhone 6 is another example of Apple’s elegant engineering,” the publication said. “The phone would have worked with just the InvenSense device, but since not all applications require the higher sensitivity and full six-axis integration, Apple added the Bosch device, which allows them to lower the power consumption while still providing a good user experience.”

Meanwhile, recent battery tests have offered slightly varied results, with Phone Arena saying neither 2014 iPhone model is able to top the competition, and AnandTech revealing that the iPhone 6 Plus’ battery life came in second to the Ascend Mate 2 during Wi-Fi web browsing. BGR has had similar results in our reviews, with iPhone 6 Plus unsurprisingly outperforming the iPhone 6 when it comes to battery life.