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ZDNET's key takeaways

• The Sennheiser Momentum 5 headphones now feature a self-replaceable battery.
• Most headphones have replaceable earpads, but batteries are less common.
• As the industry reaches a technological ceiling, self-repair is the next best thing.

Premium headphones might be reaching their ceiling. How much better can noise cancellation and sound quality get? Exactly how many on-device features can a company implement in a device with limited space? 

Review: Sennheiser Momentum 5

While figuring out the answers to these questions, companies are now exploring another front to entice consumers: better power management and battery performance. Last year, Bose's special trick was the QuietComfort Ultra 2's Bluetooth Low Energy-enabled power management feature, which effectively rendered the headphones' power button unnecessary. 

Sennheiser returned this summer with its Momentum 5 headphones, and its special trick is a self-repairable battery, a rarity in consumer headphones -- and even rarer in premium consumer models. 

How easy is it to repair the Momentum 5's battery?

The 700 mAh battery is located in the left ear cup, and Sennheiser made it easy to locate and replace yourself. The earpads connect to the cups via grooves -- similar to the Bose QuietComfort Ultra 2, rather than magnetic earcups as with the Sonos Ace and AirPods Max 2. 

Once the earpad is removed, you'll need a precision screwdriver small enough for screws that are about 2.5mm in diameter. Remove the Momentum 5's four screws, lift the battery housing, and you'll see the battery.

Also: Sony WH-1000XM6 vs. Sennheiser Momentum 5: I've tested both pairs for months, and this one wins

No glue or adhesives keep it in place; instead, there's a small connector you'll need to unplug to remove the battery, and subsequently plug the new battery into. Work backward to replace the battery housing and earpad, then you're good to go. 

Since Sennheiser just released the Momentum 5, spare parts and pricing aren't yet available. Manufacturers already don't test over-ear headphones for damage from water or dust ingress, so you should assume they can't withstand the elements. Over-ear headphones have openings near headband hinges, microphone housings, and wired ports; waterproofing is difficult to execute.

So, with the Momentum 5's battery being easily accessible and removable, you should really assume that exposure to moisture will damage the headphones. 

An industry unicorn

Self-repairability in premium consumer headphones generally begins and ends with replaceable ear pads. Though ear pads degrade in structural and hygienic integrity over time, rechargeable lithium-ion batteries also have a life cycle. If you use your headphones nearly every day for five years or so, there's a high chance their battery won't last much longer.

By the five-year mark, your headphones are likely four years outside of their warranty period, and a degraded battery from normal wear and tear isn't a valid manufacturer claim. 

Also: Sony vs. Bose: My buying advice after listening to flagship headphones from both brands

Sennheiser follows a four-year release cadence, a lengthier release schedule than Bose, Sony, and Bowers & Wilkins. By making the Momentum 5's battery and ear pads self-replaceable, it may make consumers less inclined to upgrade to future generations. 

If your headphones are four years old and you can spend $150 to make them like new, what's the rush to spend $400+ on newer headphones that can only offer incrementally improved noise cancellation?

I also see the move toward self-repair as Sennheiser buying itself time. The consumer headphones industry needs time to innovate. Sennheiser's Momentum 5 features the latest consumer audio technologies: Dolby Atmos support at the hardware level, AI-driven adaptive noise cancellation, and modern Bluetooth technologies, such as LE Audio and Auracast, which are coming in a firmware update. 

Also: I traveled 2,700 miles with Sony, Apple, and Sennheiser headphones - this pair sounded the best

As a result, there's not much left to do -- for now. We can look forward to future technologies, such as improved device tracking with Bluetooth Channel Sounding, Wi-Fi-enabled audio chips, advanced AI-powered equalizers, and headphone-compatible biometric sensors.

Until then, Sennheiser wants you to replace your battery yourself and wait for what's next.