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Comment by Ristovski | Hacker News Reader

I wonder, do those sensors have some built-in battery that lasts a long time, but ultimately the whole sensor needs to be replaced due to the electronics being potted-in?

Or is it so low power that it can use some sort of piezoelectric/MEMS power source that charges it as the wheel is spinning?

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They are battery powered. The battery lasts a few years, and conserves charge by only reporting pressure every minute after motion is detected.

Yes, they have a battery that lasts a few years. And typically, the battery alone cannot be changed, the whole unit must be replaced.

In my area, all franchised tire shops will refuse to install new tires on your car without also installing brand-new TPMS sensors, regardless of the age of the existing sensor. "Sorry, it's corporate policy."

When I bring my bike to the tire shop for new tires the guy always cuts the nozzle off and places a new one in. Might just be a safety/liability thing. Since they're also made out of rubber, which degrades.

Tire Review says [0]

> the sensors are usually powered by 3-volt lithium ion batteries, but some use 1.25-volt nickel metal hydride batteries. There are developments underway that promise battery-less sensors in the future, having the potential to dramatically change TPMS markets.

Also, YouTube has a number of videos on how to change out the batteries

[0] https://www.tirereview.com/changing-tpms-sensor-batteries/

Battery shall last for 10 years. Ideally you need to replace the tire before the battery gets empty.

Yep, it's a small battery and low-power device.

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