MicroLED Screens boost Apple Watch Batteries By …how much? 30%?

The commercialisation of microLED technology has moved at a pace over the last 5 years or so. As consumers, we’ve mainly seen it on larger scales in TVs. However, it IS coming to a Watch near you very soon. Here we talk about the improvements this technology will bring to the battery life of the not-so-humble Apple Watch.

A Brief History of microLED

The technology has several nuanced construction methods. Apple pursued one technological avenue via its acquisition of the microLED developer LuxVue in May 2014 and since 2020 has had a joint manufacturing venture well underway with AU Optronics and Epistar in Taiwan. Apple increasingly aims for vertically integrated manufacturing, meaning it owns the key elements of its supply chain but at least for now, it will still rely on Osram for microLED components, LG Display for the substrates and Taiwan Semiconductor Manufacturing for 12-inch wafers (Source: electrooptics).

Over the past few years, Apple has been variously rumoured to have its microLED scheduled for release on the Watch between 2023 and 2026. Take those rumours with as many pinches of salt as you like as there are significant technological and cost hurdles to overcome first. Perhaps the one certainty is that Apple will NOT be the first company to put microLED on a watch. But it will be one of the first. So if we see the technology on the shelves in the Samsung Galaxy Watch Ultra in late 2024, we can assume that Apple will be very close behind either releasing in the same month (Sep 2024) or a year later in Sep 2025.

It’s also highly likely that microLED will be used by Apple for next-gen AR and elsewhere in its product range.

MicroLED is an important innovation.

Q: What microLED means for the Apple Watch?

You can see the generic benefits in the chart above and how they differ from regular OLED (AMOLED) and LCD (MIP). Specifically for the Apple Watch, what will make a material competitive difference moving forward will be these

• High pixel density [Medium Impact] – Better resolution screens mean an improved ability to meaningfully show video and, of course, for more realistic still images that look like ‘the real thing’ – like a realistic analogue watch face gone digital.
• Larger Sizes [Low Impact] – It will be great to have a TV on your wrist but few people will want a large TV on their wrists! Trust me on that! Current watch sizes are in the Goldilocks zone for the sizes of existing human wrists. A few square millimetres here or there at the expense of a protective bezel will improve things a tad for the Watch Ultra but less meaningfully so for the regular Apple Watch.
• Step change improvements to battery lives [High] – You came here for this one!
• Sensor Integration [Low] – I’m assuming this means there will be various flavours of touchscreen abilities. I see this as a prerequisite to the technology’s adoption in smartwatches.
• High Brightness [Low] – Again this is a pre-requisite and must be set against the 3,000nits Apple has already achieved. That’s bright enough for commercial success.
• High Contrast [Low] – Again a pre-requisite
• Fast Response Time [Low] – Not so important for Watches in the sense that the current situation does not need improvement. This factor will nevertheless be an important consideration across Apple’s product range.
• Durability and Burn-In reduction [Low] – Not so much is offered here over and above what we already have. Burn-in problems with AMOLED are hopefully already a thing of the distant past.
• Thin [Low] – Smaller components are always better than thicker ones, other things being equal. I’m unsure of the material difference a smaller microLED display delivers, even a few cubic millimetres of volume saved can be swapped for an increase in battery capacity or a more refined, thinner Watch.
• Wide Viewing Angles [Low] – meh.
• Eco/Energy Efficiency [Low] – This will be a great one for the marketing team and gullible consumers who think they are helping the planet by binning their perfectly fine old watch to buy a new energy-efficient one.

Q: What are the Battery Life Improvements from microLED on the Apple Watch

A 30-40% component energy saving might be possible with microLED (Source: Hsiang et al), other things being equal. It is a complicated claim to make as the efficiency of the microLED chip varies depending on the colour of light; decreases in efficiency as the chip size decreases; and other factors too.

Q: What is the Apple Watch Ultra 2’s battery life?

A: The Apple Watch Ultra 2 has a battery life of up to 60 hours, but the actual, real, proper GPS recording life is 12 hours.

So if you increase that by a third you get 16 hours of battery life! Oh, dear. That’s hardly a game-changer. Still, a 30% improvement to the 60 hours gives 80 hours and that’s a great one for the marketers to claim some kind of market-leading performance (it isn’t…by a long chalk)

Then, of course, you realise that the display energy consumption is only a part of the overall consumption. So a 30% improvement in display efficiency might only translate to, say, a 10% improvement overall.

Take Out

Apple makes very specific and substantiated battery performance claims. Its claims are correct and usually a tad conservative also factoring in degradation over time. However, you need to understand the specifics of the claim.

Boosting the Apple Watch Ultra’s real sports battery life from 12 to 16 hours is a big change in Apple world. But it’s not a big change in Garmin-world. Nor in the world of any leading sports watch from Polar, Suunto or Coros. I have this sense that 20 hours of GPS recording is more of a meaningful milestone to hit. Perhaps with some other changes Apple will get there? I can’t see too many savings coming from the next-gen Apple GNSS chipset. However, its next-gen optical sensor array might include the laser-based solution proferred by Rockley Photonics. Lasers offer more precisely controlled light emissions, hence bigger energy savings.

Pie in the sky? No, Apple Vision PRO has two microLED screens which just so happens to already be the same size as needed for a watch…go figure.