Need a phone with a week-long battery? Energizer's new beast has your back

Energizer Hard Case P28K
(Image credit: Energizer/Avenir Telecom)

Energizer and its collaborative partner Avenir Telecom surprised many at MWC 2024 when the two unveiled a new rugged smartphone that houses a massive 28,000mAh battery.

It’s called the Hard Case P28K and it looks like a brick. You can find photographs taken by people at the event on X (the platform formerly known as Twitter) comparing the device to other phones. There, you’ll see it completely dwarfs an iPhone. Information about the P28K was initially scarce; however, the company managed to give us the inside scoop by giving us an official specs sheet. According to Energizer, the phone has a talk time of 122 hours (roughly five days) and a standby time of 2,253 hours which is a little over three months. TheVerge in their coverage states it can “last for a whole week” of regular usage on a single charge. 

To maintain such a big battery, creator Avenir Telecom had to make the device exceptionally bulky. Their product clocks in at 570g (well over a pound) and is 28.8mm (about an inch) thick. As TheVerge points out, that is over three times the size of an average iPhone 15. You may think a battery this large would take forever to charge, but that may not be the case. The Hard Case P28K supports 33W fast charging. A company representative told us the phone can fully charge in about an hour and a half.

Charged with features

Of course, there is more to this mobile device than just its size. It sports a 6.78-inch LCD screen capable of outputting a Full HD Plus (2,460 x 1,080 pixels) resolution image. On the back is a triple camera array consisting of a 64MP, 20MP, and 2MP lens. It’s unknown if the last two are the ultrawide and periscope options. We assume they are since the information we received didn't provide exact details. 

Something we found particularly impressive is that the Hard Case phone has a resistance rating of IP69. This means it is completely protected against dust plus it can survive underwater submersion for an extended time.

Despite these impressive features, there are a few aspects that may disappoint interested buyers. 

For starters, it doesn’t support 5G connectivity as it only goes up to 4G LTE. Under the hood, the P28K runs on a MediaTek MT6789 chipset which is the more generic name for the midrange Helio G99 SoC (system on a chip). Memory and storage space peak at 8GB and 256GB, respectively. Although you do have the option to bump the storage up to a full terabyte via SD card slot. Energizer’s smartphone will come with Android 14 installed so, at least you will have the system's latest features available.


An exact launch date has not been given. Officially, the Hard Case P28K is waiting for “final approval” from Energizer. TheVerge does, however, say the smartphone will be on sale for €249.99 this October in every country across the world – except for the United States. For whatever reason, the US is getting snubbed.

It could be because Avenir Telecom is a European corporation. We reached out to Energizer asking if it has plans for a US launch and if it could provide details on rear cameras among other things. This story will be updated at a later time.

Until then, be sure to check out TechRadar's list of the best rugged phones for 2024.

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Cesar Cadenas

Cesar Cadenas has been writing about the tech industry for several years now specializing in consumer electronics, entertainment devices, Windows, and the gaming industry. But he’s also passionate about smartphones, GPUs, and cybersecurity.