This OnePlus phone’s battery is actually bigger than the iPhone 18 Pro

Another year, another iPhone: Apple’s iPhone 18 Pro series introduces a few new features on a broad, familiar base. This new information could make the difference in convincing buyers to upgrade, but early numbers indicate that demand for the iPhone 18 Pro is slower than usual. But let’s talk about that boring basics – particularly the device batteries that make phones so mobile – and also call on a rival phone maker that just left the North American market: OnePlus.

The SIM variant of the iPhone 18 Pro has a battery with a capacity of 4,056 milliamp-hours, while the SIM-equipped iPhone 18 Pro Max comes with a 5,391 mAh pack. These numbers represent a slight increase over the iPhone 17 Pro series, and they’ll likely be slightly higher in markets like the US, where Apple sells eSIM-only phones – but they’re nothing earth-shattering, especially since you’re paying $1,199 or more for the device. So why not pay less? OnePlus has just launched some new entries in its budget lineup, and one of them is the OnePlus N6: it has an 8,000 mAh battery, and in India it sells for around US$250. If you haven’t yet discovered silicon-carbon anodes, get ready to find out.

As people continue to adopt electric vehicles and smartphones in their lives, researchers have advanced lithium battery technology to extend their lifespan without a charger. Silicon-carbon anodes (the part of the battery that supports it) have enabled a whole wave of Chinese Android phones to have power capacities ranging from 6,000 milliamp-hours to 10,000 mAh – and none of them look like bricks.

So why silicon-carbon? Well, carbon (in the form of graphite) is the anode material of choice in lithium-ion batteries because it is a stable substance, particularly in its role as an electrode processing a flow of electrons. However, its energy storage has left engineers wanting more, especially compared to silicon which has a capacity 10 times that of graphite. The problem is that silicon is more volatile and tends to expand when lithiated – and many of us know how risky it is to be near a swollen battery ready to explode.

The solution? Enjoy the best of both worlds and go hybrid. Silicon-carbon anodes still pose a greater volatility risk on paper, but we have not heard of a massive recall involving devices equipped with such batteries. At the same time, consumers have more power in their phones and spend more time without a connection.

Apple and Google don’t usually talk about batteries in public, but the general reason they’ve stayed away from silicon-carbon in their phones appears to be related to a lack of trust. That said, Samsung recently achieved its first silicon-carbon integration with the launch of its Galaxy Z Fold 8 series of foldable phones. Given the tattered reputation it earned during the Galaxy Note 7 recall saga in 2017, we’ll have to see if smooth sailing here is a prelude to proliferation among rivals.

Back to OnePlus where we should note that the N6 is just one of several phones with a silicon-carbon battery. The OnePlus Nord 6, which costs the equivalent of US$500, is absolutely brilliant with a 9,000 mAh cell. However, you may be wondering how well this translates into real-world usage. For its part, Apple certifies in its European energy labels for the iPhone 18 Pro and Pro Max that they will last up to 52 and 62 hours respectively. Oddly, OnePlus claims three or more days with the 7,500 mAh tank on the N6 and only two and a half days on the Nord 6, likely due to a more power-hungry apps processor. That said, in internal testing with a continuous stream of YouTube videos, the N6 is rated at 24.8 hours while the Nord 6 was reduced to 26.9 hours.