BLE TPMS Alarm in the Background A phone-based TPMS is only useful if the alarm still fires when the app is not on screen. What background operation means on Android and iOS, and how to test it.

The question behind the question

When a buyer asks "does it work in the background", the real question is: if the driver never opens the app, does anything happen when a tyre drops? A monitoring system that only reports while somebody is looking at it is not monitoring, it is a gauge with a nicer screen.

So the honest answer has two parts: what the app does while it runs in the background, and what a phone platform will let an app do at all. Those are not the same thing.

• BLE TPMS alarm works with the app in the background

(Video: the alarm firing with the app minimised.)

What background means in practice

Situation	What happens
App open, screen on	Live pressure and temperature for every bound wheel
App minimised (background)	The app keeps the BLE connection where the platform allows it and raises a notification when a threshold is crossed
App swiped away (killed)	The connection ends. No alarm until the app is opened again
Phone locked for hours	Depends on the platform's background policy for the phone in question

That third row is the one to say out loud. No BLE app can promise an alarm for a process that the operating system has terminated — anyone claiming otherwise is describing a receiver-based system, not a phone-based one.

How we test it (and how you can)

1. Bind each sensor to a wheel in the app.
2. Set a low-pressure threshold that is above the tyre's current pressure by a margin you can

reproduce (for example, 30 kPa above reading).

1. Minimise the app — do not leave it on screen.
2. Release air from one tyre until it crosses the threshold.
3. Watch: does a notification arrive, and how long after the crossing?

Repeat with the app killed: the expected result is no alarm, which is the point — it tells you what the system depends on.

Where a phone-based alarm is enough, and where it is not

Enough: a fleet where somebody walks the machines with a phone, a workshop checking tyres per shift, a trailer or rental asset where the check is periodic and recorded.

Not enough: a machine where an alarm has to reach a control room, or a driver who will not have the app open. That is a receiver and a bus output — a different product on our industrial line, and we will say so rather than stretch this one.

What we will not claim

We do not claim a guaranteed alarm on every phone model with every battery-saving setting. Android vendors differ in how aggressively they stop background apps, and iOS applies its own rules. What we can say is what the app does when it is allowed to run, and what to test on the phone you will actually deploy.

FAQ

Does the alarm work if the phone screen is off? Yes, while the app is still running in the background and the platform keeps the connection — the notification arrives with the screen off.

What if the user force-closes the app? Then there is no alarm until it is opened again. A phone cannot watch a BLE connection from a terminated process.

Can it alarm on several phones at once? Each phone binds its own sensors; whether one vehicle can be monitored from two phones depends on the setup you plan. Tell us the deployment and we will answer for that case.

How often does it read? The sensor measures every 10 seconds and broadcasts every 5 minutes; the app reads on its own schedule while connected.

中文要点

• 后台能用 ≠ 进程被杀还能用：App 被系统结束进程后，蓝牙连接就断了，不会报警——这是手机平台的边界，不是我们偷懒。
• 真正的验收方法：绑定轮位 → 设一个能复现的阈值 → 把 App 最小化 → 放气越过阈值 → 看通知多久到。
• 适用：有人拿手机巡检的车队、按班次查胎的车间、租赁/挂车这类"定期有记录"的场景。
• 不适用：报警要进中控室、或司机根本不开 App 的机器——那是接收器 + 总线输出的事（工业线的产品）。