The Apple Watch Series 5 is the first to feature an always-on display, and Apple touted that it was able to achieve that without a measurable impact on battery life. Now that the Series 5 is widely available, however, some users are reporting mixed results when it comes to battery performance – but it could be a software bug.

Apple says the Apple Watch Series 5 can achieve up to 18 hours of battery life, which is the same as what it also advertised for the Series 4. This is an impressive accomplishment, considering the potential drain of the always-on display feature.

Since the Apple Watch Series 5 was released on Friday, however, some users have taken to Twitter to question the device’s battery performance. Users have been putting the device through their normal use tests and noticed that battery life is not quite as good as the Series 4, and in some cases not up to Apple’s 18-hour claim.

Apple Watch Series 5 press reviews hit last week, and reviewers were generally cautiously optimistic about battery performance. The consensus among many reviewers was that the Apple Watch Series 5 generally lived up to Apple’s 18 hour battery life claim, but that it was not able to overachieve like the Series 4 was.

It was common for the Apple Watch Series 4 to last longer than 18-hours, especially depending on how you used it. For instance, if you had a day without a workout, you’d likely make it significantly longer than 18-hours.

One important thing to note is that it’s possible Apple could resolve these issues with software updates. It could be that watchOS 6 has some optimization issues on the Apple Watch Series 5, and that watchOS 6.1 could improve battery life. Some Apple Watch Series 4 users have also reported battery life issues on watchOS 6 as well, which further indicates it could be a software problem.

Are you an Apple Watch Series 5 owner? What sort of battery life have you noticed so far? Let us know down in the comments and the poll below!

Day one battery review:

iPhone 11 Pro: 🤯 how can it be this good‽

40mm Series 5 Cellular: 🤯 how can it be this bad?

(I wonder if using the compass complication was a power self-own? 🤔)

— Casey Liss (@caseyliss) September 21, 2019

Anyone notice the #applewatch series 5 has substantially less battery than the series 4? It’s been two days and hasn’t gotten anywhere near what the previous version had.

— Daniel Hall (@DanielJHall) September 22, 2019

Does anyone else find that having the Noise monitoring complication on Apple #Watch Series 5 turned on drains the battery to zero in about six hours?

— John J. Irvine (@EB_John) September 22, 2019

After one day of wear, without workouts, my Series 5 Apple Watch is down to 38% power. This is significantly worse than the battery for my S4, which even after a year lasted 2.5 days. And for what – so the screen can be on when I’m not looking at it?

— Paul Hudson (@twostraws) September 22, 2019

The watch died shortly after the 1:14am screenshot. Taking the watch off of the charger around 11:50am at 100% and it dying around 1:16am is not good. Advertising “all day battery life” and it not even lasting over 13 hours is BS. Thanks @Apple pic.twitter.com/UTgK4HMSyG

— C.M. Pun (Mikey) (@3m3h3n) September 22, 2019