I tested the world’s first phone with a 10,000 mAh battery: here’s how long it lasted

(Image credit: Future)

This is the first key takeaway: the Realme P4 Power won’t be sold in most global markets; it will be available only in India and certain other key countries. However, there’s a key reason for this: shipping and storage laws.

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Having tested it, the Realme P4 Power will probably live up to the marketing claims: it lasted me over three days on a full charge and is on track to last around 13 days on standby.

The Realme P4 Power uses multiple smaller-capacity battery cells rather than a single large 10,001 mAh cell, allowing it to comply with globally accepted rules on the shipment and storage of batteries. In particular, this rule is likely the reason we’ve yet to see companies like Samsung expand to much larger batteries; once the combined battery size reaches a certain threshold, it requires more specialized storage and shipping that fewer partners can safely comply with.

You may be wondering, what about selling on Amazon? I asked Chase this question, and the answer was surprisingly telling: Amazon also has its own requirements around size and wattage. The Realme P4 Power is large enough that it would require Realme to have its own storage facilities and ship directly from there to customers, rather than rely on Amazon’s own fulfillment centers.

Among other reasons, it’s also why the release is more limited than some of Realme’s other phones. A key market for the Realme P4 Power is India, where it’s being marketed against the leading 10,000 mAh power bank. This also solves the above problem because India has different rules, and its proximity to China makes it easy to ship devices to the country.

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(Image credit: Future)

The P4 Power is the latest in a line of battery breakthroughs from Realme. The company was the first to achieve 240W wired charging on a phone, and then followed this up with 320W charging. Both of these specs were in phones sold to customers, rather than just concept devices as we’ve seen from other companies.

The P4 Power follows from a Realme concept phone that launched a few months ago with a 10,000 mAh battery, but with a key difference: its Titan battery technology, a term that describes the best battery life Realme has to offer. Given that the company has been a pioneer in introducing new battery technologies, it’s safe to say the Titan battery is a market leader.

Is it just a marketing slogan? According to Chase, the Titan title symbolizes that the phone in question “houses a battery that belongs to the top tier, whether in terms of highest capacity or top-tier battery performance”. It’s also been used previously to denote the highest charging speeds Realme offered.

The company backed up these claims during a unique factory tour that showcased how they test the batteries: from drop tests to fire testing – yes, trying to test the limits and ensure the battery won’t explode – and even a test where we were able to jump on the battery. That’s backed up by the temperature testing, where Realme tests its batteries at a wider range of temperatures (-30°C to 56°C) than the competition to ensure it can withstand the elements wherever you take the phone. This is a battery that’s designed to survive.

(Image credit: Future)

Of course, testing a battery is one thing, but another key question is: how did the company make a 10,001 mAh battery, and why isn’t everyone making one? The answer is that it’s “far from the simple matter of stacking capacity”; rather, “it’s a systemic breakthrough in materials, structure, and algorithms.”

Realme had to focus on three key areas: materials, safety, and solving a key problem with silicon-carbon batteries: increased degradation over time.

How did the company make a 10,001 mAh battery, and why isn’t everyone making one? The answer is that ‘it’s a systemic breakthrough in materials, structure, and algorithms.’

First, this third-generation Silicon Carbon battery moves away from the block-type and hemispherical designs used in the first and second generation Silicon Carbon batteries, in favor of a new spherical silicon-carbon anode material. According to Chase, and backed up by images the company showed us in a presentation:

“The key breakthrough lies in its biomimetic spherical honeycomb structure, which, through precise arrangement like a honeycomb, effectively suppresses the expansion of silicon material during charging and discharging, increasing cycle life by 30% compared to the previous generation. This is the “complete form” of silicon-carbon technology.”

A key issue for any large battery is safety, and, as with Lithium-Ion batteries before them, all Silicon Carbon batteries will degrade over time. This can pose a key challenge for users, especially when the battery is expected to last as long as they use it, if not longer.

To solve this, Realme instituted the above testing regime, which also includes 1-meter drop tests, sought out third-party battery certification from renowned testing firm TÜV Rheinland (with the P4 Power achieving the first-ever 5-star rating on these tests), and developed a new algorithm to optimize and extend the battery’s longevity. And it’s this algorithm that is where the Realme P4 Power has me excited for the future of smartphones.

Having tested it, the Realme P4 Power will probably live up to the marketing claims: it lasted me over three days on a full charge and is on track to last around 13 days on standby.

Many companies are developing larger batteries for their smartphones, but, as mentioned above, this poses a key safety challenge for customers. To solve this, Realme developed a new Titan Long-Life Algorithm that leverages AI to address the degradation problem.

According to Chase, the Titan Long-Life Algorithm “integrates AI charging/discharging strategies with a silicon degradation model. It dynamically learns user habits and optimizes charging behavior, ultimately achieving over 94% battery health after three years and over 80% after eight years.”

This is key, as a common trend on social media is for people to post screenshots of their iPhone battery health after 6-12 months, which usually shows a noticeable degradation. When I sold my iPhone 16 Pro last September after 12 months of use, its battery health had dropped to 91%. Apple will replace your battery (depending on your warranty and coverage) once it drops to 80%.

The new algorithm promises to give the battery a much slower rate of degradation. Realme has made bold claims of 94% health after three years and 80% after eight years. Only time will tell whether this lives up to the promise, but I hope it does. Battery health and longevity are more important than ever, especially as consumers keep their devices for longer: according to Verizon CFO Tony Skiadas in March last year, the average customer now keeps their phone for 42 months, or 3.5 years.

(Image credit: Future)

Of course, it’s 2026, and a big battery isn’t enough to make a product truly viable. If it were, everyone would be using the Energizer Hard Case P28K (28,000 mAh) or the 8849 TANK 3 (23,800 mAh). A side note: my flight back from this trip had me sitting next to a passenger who willingly used a TANK 3, simply because battery and durability are key, and he was persuaded by the sleek design of the P4 Power despite its large battery and fast charging.

Realme has made bold claims of 94% battery health after three years and 80% after eight years.

The Realme P4 Power doesn’t have the extreme charging speeds of past Realme Titan devices, but it does offer still impressive 80W charging. You might be wondering why, and according to Chase, the reason is two-fold. He said:

First and foremost, the P4 Power’s core innovation is its massive 10,001 mAh battery. When battery capacity reaches 10,000 mAh, users need to charge far less frequently… Forcing a higher-power fast-charging module would have compromised this sleek design. We prioritized “comfort in one-handed use,” ensuring that a large-battery phone can still offer a flagship feel.

Of course, 80W charging is more than enough and should charge the phone to full in under an hour. There’s also another key feature every brand should have: 27W reverse charging.

Yes, the big battery and fast reverse charging are key tenets of the P4 Power, but it also has a few other specs that stand out. There’s a 6.78-inch OLED display that supports a 144Hz refresh rate, making it one of the few phones to go beyond the more common 120Hz. There’s also a 50MP main camera, although the large battery limits the other two rear lenses to an 8MP ultrawide and a 2MP macro camera.

The phone measures just 9.08mm thin, weighs 219 grams, and also comes with IP68 and IP69 ratings, meaning it is water-resistant even under high-pressure jets. This means you can probably put it through the car wash and it’ll survive, though you definitely shouldn’t try it. It’s powered by the MediaTek Dimensity 7400 Ultra processor, paired with 12GB of RAM and 256GB of storage, and runs Android 16, with 3 years of OS updates and 4 years of security updates.

Overall, this phone is all about the battery life. Before learning about it, I would likely have dismissed it as a gimmick, but now that I’ve used it, I’m excited to see this third-generation silicon-carbon battery technology come to other Realme devices.