Foldables are a different experience altogether compared to regular slab smartphones. You get a phone that fits comfortably in your pocket, but open it up, and there’s a much larger screen to work with. It’s great for watching videos, using multiple apps at once, or getting some work done when you’re away from your laptop. But all that screen real estate also means your phone has to work harder throughout the day. And that’s where battery life comes into the picture. The Samsung Galaxy Z Fold8 and Apple’s iPhone Duo are two interesting book-style foldables, or rather, passport-style foldable phones, with both promising a full-fledged smartphone experience with a much larger canvas when unfolded. But which one manages power better when put to the test? Well, we put them through the wringer in a six-hour battery endurance showdown at the Digit Test Labs to find out.
On paper, the two foldables have almost identical battery capacities. The Samsung Galaxy Z Fold8 packs a 4,800mAh silicon-carbon (SiC) battery, while the iPhone Duo gets a slightly larger 4,833mAh lithium-ion unit. However, there’s an interesting difference in the battery technology used by both phones. The Galaxy Z Fold8 uses a silicon-carbon (SiC) battery, which offers higher energy density than conventional lithium-ion batteries. In simple terms, it can store more energy without taking up as much space, giving Samsung more flexibility when designing a slim foldable like the Z Fold8. And, considering this is a foldable phone we are talking about, every millimetre of internal space matters.
But endurance isn’t determined by capacity or battery chemistry alone. The displays, processor, software optimisation, and how efficiently a phone handles demanding tasks all play their part. And with foldables, there’s a lot more screen to power. Speaking of which, the Galaxy Z Fold8 has a 7.6-inch inner display, alongside a 5.5-inch cover screen. The iPhone Duo, on the other hand, also has a 7.6-inch inner display but a slightly smaller 5.4-inch cover display.
For this comparison, we wanted to see how the Galaxy Z Fold8 and iPhone Duo would hold up with the kind of things most of us do every day. We started with two hours of YouTube playback, followed by an hour of 4K video recording. Then came an hour of WhatsApp video calling, an hour of gaming, and finally, an hour of scrolling through Instagram Reels.
We wanted to go beyond just watching videos and see how both phones handle everyday tasks that are more demanding. Recording 4K videos, making WhatsApp video calls, and playing a demanding game all put different levels of strain on the battery. So, we switched between these activities over six hours to see how much charge each phone could hold on to and which one would last longer.
We began with two hours of continuous YouTube video playback on both foldables, using their large inner displays. Both the Galaxy Z Fold8 and iPhone Duo feature a 7.6-inch internal screen, giving you plenty of room to watch videos without having to reach for a tablet. This larger canvas makes video consumption a lot more enjoyable, although it also means there’s a sizeable display drawing power throughout the test.
The Galaxy Z Fold8 lost 12% of its battery (576mAh), finishing the round with 88% charge remaining. The iPhone Duo, meanwhile, lost 14% (676.6mAh), leaving it with 86% battery. It’s a fairly close start, but the Galaxy Z Fold 8 takes the early lead, consuming less power despite having a slightly smaller battery.
Next, we moved on to one hour of 4K video recording. To keep things consistent, we used the outer displays on both phones and recorded 30 minutes of footage using the rear camera, followed by another 30 minutes using the front camera. Both recordings were done at 4K 60fps. This is a much heavier workload, as the camera sensors, image processing, and video encoding all remain active for an extended period.
The Galaxy Z Fold8 lost another 18% of its battery (864mAh), bringing its remaining charge down to 70%. The iPhone Duo, on the other hand, lost 21% (1,014.9mAh), leaving it with 65% battery. That’s a five-percentage-point lead for Samsung after three hours of testing.
After 4K video recording, we moved on to an hour of WhatsApp video calling. This is something many of us do regularly, whether it’s catching up with family, talking to friends, or attending a quick work meeting. And video calls can be quite demanding on a phone, as the camera, display, speakers, and network connection are all being used at the same time. The Galaxy Z Fold8 lost 14% of its battery (672mAh), bringing its remaining charge down to 56%. The iPhone Duo drained 16% (773.3mAh), leaving it with 49% charge. Samsung now has a seven-percentage-point lead over Apple after four hours of testing.
Next up is an hour of gaming on the inner screens, which puts considerably more pressure on both phones. Running graphics-intensive games for an extended period means the processor and GPU have to work harder, while the large inner displays add to the load. The Galaxy Z Fold8 lost 18% of its battery (864mAh) during this round, bringing its remaining charge down to 38%. The iPhone Duo, meanwhile, drained 20% (966.6mAh), leaving it with 29% battery. Samsung now has a nine-percentage-point lead. What’s interesting is that the gap has continued to widen with each demanding activity, with the Galaxy Z Fold 8 managing to retain more charge even after an hour of gaming.
For the final round, we spent an hour scrolling through Instagram Reels on both phones. It’s something most of us do without thinking, and an hour of short-form video can add up, especially on a large foldable display.
The Galaxy Z Fold8 lost another 10% of its battery (480mAh), finishing the six-hour test with 28% charge remaining. The iPhone Duo drained 11% (531.6mAh), bringing its remaining charge down to 18%. That’s a ten-percentage-point difference by the end of the six-hour test, with the Galaxy Z Fold8 finishing comfortably ahead of Apple’s foldable.
Here’s the complete breakdown of the total battery consumption across all five activities in a span of six hours.
| BATTERY DRAIN TEST | Galaxy Z Fold8 4800 mAh Battery | iPhone Duo 4833 mAh Battery |
| 2 Hour YT Video Playback | 88% (576 mAh Drain) – 12% Drain | 86% (676.6 mAh Drain) – 14% Drain |
| 1 Hour Video Recording | 70% (864 mAh Drain) – 18% Drain | 65% (1014.9 mAh Drain) – 21% Drain |
| 1 Hour WhatsApp Video Calling | 56% (672 mAh Drain) – 14% Drain | 49% (773.3 mAh Drain) – 16% Drain |
| 1 Hour Gaming | 38% (864 mAh Drain) – 18% Drain | 29% (966.6 mAh Drain) – 20% Drain |
| 1 Hour Instagram Reels | 28% (480 mAh Drain) – 10% Drain | 18% (531.6 mAh Drain) – 11% Drain |
| Total Drain (After 6 Hours) | 72% / 3456 mAh Drain | 82% / 3963 mAh Drain |
After six hours of switching between YouTube video playback, 4K recording, video calls, gaming, and social media, the Galaxy Z Fold8 comes out ahead. It finishes with 28% battery remaining, while the iPhone Duo finishes with 18%. That’s a ten-percentage-point difference, which is quite a lot when you consider that both phones have almost identical battery capacities.
To recap, the Galaxy Z Fold8 consumed 3,456mAh during the six-hour testing, compared to 3,963mAh on the iPhone Duo. What’s worth noting is that Samsung maintained its lead across all five activities, and the gap became wider as we moved to more demanding tasks such as video recording and gaming.
Of course, the iPhone Duo is no slouch either. It puts up a decent fight, considering how closely matched the two phones are on paper. However, the Galaxy Z Fold8 also manages to hold on to more battery, which is important when you’re using the large inner screen for watching videos, multitasking, or getting work done throughout the day. Having 28% charge left after six hours of such usage, rather than 18%, could make a real difference towards the end of the day.
Overall, based on the results, the Galaxy Z Fold8 takes the win in Digit’s six-hour battery drain test comparison, showing that Samsung’s choice of battery technology and overall power management give it an edge over Apple’s iPhone Duo.