Google is planning a new update for its upcoming Pixel 9a which includes a new feature dedicated to protecting and prolonging the phone's battery. While the goal is longevity, this new battery management feature will actually end up reducing the battery capacity of the Pixel 9a over time. It won't just be the Pixel 9a, as other Pixel series phones will eventually receive the feature too. The kicker, though, is Pixel 9a users can't turn this feature off.Why do Lithium-ion batteries need management?All lithium-ion batteries degrade over time. As you use your smartphone, and as you continue to charge it, the total battery capacity goes down. Eventually, charging your phone to 100% doesn't last as long as it used to: maybe 100% battery today really gets you 80% of the battery capacity of the battery when it was new.Manufacturers have introduced workarounds that help prolong the inevitable, by limiting how much you actually charge the battery. Apple has an iPhone feature that lets users limit the battery charging between 80% and 95%. There are apps that do this for the Mac as well. These measures do go a long way in prolonging the battery of a device. In the short term, you might not notice any difference, but these changes can lead to batteries lasting for months or years longer than they used to. Now that Google is supporting Pixel devices with seven years of software updates, it's in the company's interest to ensure its devices' batteries are performing at a level that can support the new software and features that will be added in the years to come. How Google's Battery Health Assistance worksAs first reported by 9to5Google, Google is adding a new "Battery Health Assistance" feature to Pixel phones, starting with the Pixel 9a. Google is taking quite a different path than Apple here: Instead of providing an option to limit battery charging overnight, or to a particular percentage, Google will start to reduce the battery's maximum voltage after the Pixel 9a crosses 200 charge cycles.A charging cycle doesn't mean a single charging session. It means charging your phone from zero to 100%, even if that happens in breaks, over multiple days. If your phone drops from 100% to 60%, then you charge it to 100% again, that's 40% of a full charge cycle. If you then let it fall to 40%, and charge it back up to 100%, that's 60% of cyclecombined, that's one full cycle. So, once the system clocks 200 of those cycles, Battery Health Assistance kicks in. Google will do this automatically and in the background, hopefully without being too intrusive. Google says that users may notice small decreases in the battery's runtime as the battery ages, andwill continue to reduce voltage for up to 1,000 charging cycles. Once this feature rolls out to existing Pixel devices, you will be able to turn it off if you preferwith one exception.Mandatory Battery Health AssistanceAs I mentioned above, the Pixel 9a is currently the only Google smartphone that won't have an off switch for Battery Health Assistance. While this is a good feature, and it will prolong the battery life of the smartphone, not having the option to turn it off, and thus having no choice in whether to use the full charging capacity of the phone, is a bummer. Since the Pixel 9a has the biggest battery ever in a Pixel phone (5,100 mAh), your phone's battery should be in good shape for a while. But the fact that Google is forcing this feature onto its users, and not presenting it as a choice, will likely rub Pixel 9a users the wrong wayespecially since other Pixel users will have a choice in the matter. At the time of writing I don't know how this feature will work, how it will be turned off, but I suspect that will go hand in hand with the upcoming Android 16's new Battery Health section that lets users limit charging capacity to 80%, shows battery cycle count, among other battery related data.This, along with the fact that the Pixel 9a will miss out on the top-tier AI features, differentiates it from the Pixel 9 (which can be found as low as $600 on sale). Perhaps the latter is the phone to go with for users who want as much control over their device as possible.