Questions people ask before trying it

Does it survive rain and a drop?

Unknown, and we will not pretend otherwise. The Xteink X4 is a consumer e-reader with no IP rating, and nobody here has tested one wet or dropped. Treat it as a device that needs a case or a dry pocket in the wet. If that is a deal breaker for you today, it should be.

What happens when Bluetooth drops while you are out?

The map stays exactly as it was: e-ink holds the last picture with no power, so you keep the frame you were reading. The status strip shows the link as gone. Buttons still work, so you can pan and zoom around the ground already on the card. When the phone comes back, the app reconnects on its own, nothing tapped, and the dot picks up again.

One thing is missing and it matters: there is no fix age on screen. The header shows the current time rather than the time of the last position, so a dot that is twenty minutes old looks as current as one from a second ago. That was a deliberate call and it is written down as a cost. A staleness marker is a small change, not a rewrite, and nobody has been out long enough with it yet to say how badly it bites.

Does it do anything with no phone at all?

Yes, as a map, no, as a position. It opens at the last fix it remembers and draws the area from tiles on the SD card, and you can pan and zoom with the buttons like a paper map that happens to have a marker on the last place it saw you. What it cannot do is follow you: the GPS fix comes from the phone over Bluetooth, because these readers have no GNSS receiver of their own. That is hardware, not a setting.

So it is not standalone. Why build it that way?

Because the phone is not the problem, the phone as your screen is. The pocket is where a phone is good at its job: it has the GNSS chip, the data connection and the battery you can charge anywhere. Duplicating all three in the second screen buys a device to charge twice over and a second GNSS to lose under trees. What we do want is the opposite of that duplication, a reader with its own receiver, and that is a different device rather than a setting.

Does it need mobile data?

Only to bring new ground in. A square already on the card draws with the phone in airplane mode and no signal for a hundred kilometres. Reaching ground nobody has built yet is a request: the reader asks, the phone fetches, the tile server builds the area, usually inside five minutes. Both of the data spending features, that fetch and the check for out-of-date squares, are off until you switch them on, because it is your data plan.

How long does a charge last?

With the map screen up and a phone connected the battery drains about 3.9 % an hour, which is about 25 hours on a charge. We quote 10 h+ publicly, because these are days out rather than controlled bench tests. The figure is a battery percentage slope, not an inline meter reading, so treat it as an indication and not a spec. An earlier build without Bluetooth modem sleep, a setting the firmware no longer ships, came out at about 15 hours. Holding a picture costs nothing: the power goes into changing it.

Can I read it at night?

On the X4 Pro, yes. It has a frontlight, and our own build drove it on a real unit on 9 September 2026. On the plain X4 and the X3, no: a reflective panel needs light, the same as paper, and neither of those readers carries one. What is not answered on the X4 Pro is how the light behaves over a long session, how bright it runs and whether it flashes at boot, so treat night reading as working rather than tuned.

Does it work in the cold?

Not measured, so here is what is known instead. E-ink panels of this class are specified from 0 to 50 °C, and below freezing they get slower and ghost more. The effect is sluggishness, not damage, and it reverses when the panel warms. Nobody has put an X4 in frost and timed a refresh, which is the cheapest missing measurement in the project.

Is there a subscription?

No, and there will never be one for reading a map. The firmware and the phone app are MIT licensed and public, and the maps are OpenStreetMap, so there is no region to unlock. Building and hosting tiles does cost money every month: if a paid tier ever appears it covers that, priority builds and hosted access, never the software on your device and never a square already on your card.

Will it tell me where to turn?

No. There is no voice, no rerouting and no turn prompt. You get the map, your position, your route drawn on it, and pins you set yourself. Miss a turn and you notice the way you would on paper, by looking, whether you are walking it or riding it. Off route warning is planned and not built. If you want instructions, a Garmin or a phone app is the right tool, and the comparison page says so plainly.

Which readers does it run on, and where do I get one?

The Xteink X4 today, and that is an awkward answer: Xteink discontinued the X4 in August 2026 and took its product page down, so the device every measurement here was taken on is one you can no longer buy. The X3 runs from the same binary, is still sold, and was flashed and run on 9 September 2026, though the chrome still sits wrong on its narrower screen. The X4 Pro is a different chip with its own build, released and run on a real unit the same day. A LilyGo T5 S3 Pro also runs it: that one is a bare development board, not an Xteink product, but its alpha build is hardware-verified (booted, touch lock confirmed) and sits alongside the other three on the flasher. The install page says per device which claims are code and which are measured.

We do not tell you which reader to buy. What each one can and cannot do today is on the hardware page, per device, and the install page says which build goes on which. One thing worth knowing wherever you buy: the CrossPoint project lists these readers on its devices page with an affiliate link to Xteink’s own store, so a purchase through it sends a cut back to the upstream contributors whose work this is forked from.

How do I install it?

Downloads exist since 22 August 2026: a firmware image set per reader and an APK for the phone, with the commands next to them on the install page. It is still a maker's install: a USB cable, one command line tool, about half an hour, and no toolchain to build anything.

A one click installer in the browser and a signed app are the next milestone. Both are about lowering the effort, not about what the device can do. What runs today is listed, dated, on the development page, and the phone side is on the app page.