What you need to knowA report on X claims that Samsung has started testing extremely large batteries for Galaxy phones.The tipster’s report clocked a 12,000mAh battery and an 18,000mAh battery, though there was one at 20,000mAh that failed at 960 charging cycles.Rumors last year said Samsung might have 6,000mAh to 7,000mAh ready for its 2026 phones, but that is not the case, as the S26 Ultra still sees a 5,000mAh battery.
There’s no getting around it: Samsung’s phone batteries could be better, and it seems tipsters agree, as reports claim tests are underway.
Documents out of Samsung’s SDI have allegedly surfaced, courtesy of tipster phonefuturist on X (via Notebook Check). The tipster’s post claims that Samsung has documented its work on developing a 12,000mAh silicon-carbon phone battery, which could be placed in a future Galaxy device. Specifically, the SDI documents were about the company’s tests for the batteries to see if they’re—for one—viable and their potential lifespans.
Android Central’s Take
For someone who likes the Galaxy S Ultra model, I’d love a bigger battery. The battery, as it stands now, isn’t terrible (this is coming from S25 Ultra experience), but it could be better. Look at what OnePlus is doing with its Glacier tech batteries. Look at any of the other overseas OEMs from China and what they’re doing. It’s very clear that Samsung is feeling the pressure. I’m just not sure why it’s taken them this long to do something about it, if this leak is to be believed.
The 12,000mAh battery is testng supposedly utilizing a “dual stacked cell” structure. Samsung is seemingly pairing a 6,800mAh and a 5,200mAh battery to get this done. The stack thickness is reportedly around 9.0mm. The file for this battery suggests Samsung is still working on testing its “cycle durability target.” Right now, it claims the battery can survive 1,500 charging cycles before it falls to 80% capacity.
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The tipster adds the company is also testing an 18,000mAh battery with a “tri-cell vertical stack.” This would consist of batteries with 6,699mAh, 6,000mAh, and 5,257mAh capacities. This would push things on the larger side, with the thickness measured at 12.3mm (and we know Samsung loves its thin phones). The final alleged battery in testing is a ginormous 20,000mAh battery. The tipster states this one failed at 960 charging cycles, so maybe this one will remain a dream for now.
Don’t mind us, just stuck in 2019
(Image credit: Derrek Lee / Android Central)
If we take a look back at last year’s rumors, there was speculation that Samsung could finally catch up to the competition’s batteries. It seemed like we might finally get out of 2019 with bigger batteries. Reports purported that the company was working on implementing batteries ranging from 6,000mAh to 7,000mAh in its phones for 2026. Charging wasn’t touched on, but the device’s batteries were the main talking point.
Android Central’s Take
I feel as though Samsung’s been so preoccupied with its thin phone era, its AI Phone era, that it’s forgetting a key component. No one likes throwing their phone on the charger multiple times in a day. It’s the longevity of our devices that keep us feeling good, keep us going without worry. Of course, Samsung’s Galaxy flagships have come a long way, but it’s very clear that there’s more work to be done. Batteries, for starters (and preferably), is a good place to start.
Unfortunately, as we’ve already seen with the Galaxy S26 series, nothing is different. The Galaxy S26 Ultra still rocks a 5,000mAh battery, leaving the base and Plus models with a 4,300mAh and a 4,900mAh battery, respectively. As mentioned before, companies like OnePlus offer huge 7,000mAh batteries with 100W wired charging capabilities. This not only extends the user’s time on their phone, but also gets them back on it quicker.