E-Ink A2 Refresh vs HD Mode: How PDF Scrolling Quietly Kills Battery

E-ink marketing still sells a week of battery as if the panel were a Paperwhite showing a novel. Then you open a 120-page PDF, turn on a fast refresh mode so scrolling does not feel like a slideshow, and the week becomes a long afternoon. The drain is not mysterious. Fast waveform modes update more pixels more often. HD modes update fewer times and look like paper. PDF scrolling wants the first and pays with the second.

Boox calls some of this Super Refresh. Other vendors hide the same idea under A2, speed, balanced, or “auto.” The names wander. The physics does not. I have killed a Go-class tablet by skimming a scanned manual in A2 with the front light up, then blamed the battery as if it had failed. It had done what I asked.

What A2 and HD are doing

A full HD-style refresh drives the particles toward a clean black or white and often flashes the screen to clear ghosts. It looks finished. It is slow if you flick pages like a phone. A2-style modes skip the full cleanup. They push updates faster, leave gray residue, and keep the controller busier. Ghosting is not a defect in that mode. It is the receipt.

Partial updates and “regal” style waveforms sit in the middle depending on the controller. I am not writing a driver paper. I am writing the user rule: the more the screen pretends to be LCD, the more it costs. E-ink’s power miracle assumes the picture stays still. Scrolling is the opposite of still.

PDFs are worst-case e-ink

A novel is a page of text, a tap, a new page. Many pixels change, but the cadence is human. A PDF you pinch, pan, and scroll is a video you are too polite to call a video. Every pan invalidates a region. A2 makes that region cheap to look at and expensive over an hour. HD makes it expensive to look at and cheaper if you stop touching it.

Scans are worse than born-digital files. High-contrast type can survive a dirty refresh. Gray photographs and faint schematics cannot. You raise contrast in software, which can force even more processing, then you raise the front light to read the ghosts. Light is a second battery killer people forget because they are staring at the first.

Two-column papers invite zoom. Zoom plus A2 is how I have watched a SoC stay awake. Android e-ink tablets are computers. The panel is one draw. The CPU that decodes the PDF and the GPU-ish path that composites it are others. Fast refresh does not only tax the waveform. It taxes the habit of continuous motion.

The auto mode that trains you poorly

Auto refresh sounds adult. It often means “A2 while you move, HD when you pause.” That is reasonable and still trains you to keep moving. If the tablet is pleasant only while you flick, you flick more. I have caught myself scrubbing a document I already understood because the motion felt like progress. HD mode makes you stop and read. That is better for comprehension and for watt-hours.

I set a personal rule. Continuous scroll is A2 only for skimming a table of contents or hunting a figure. Once I find the page, I switch to HD or let auto settle, and I stop treating the document like a social feed. If a vendor has no easy toggle, I use a full refresh gesture when ghosts hide a minus sign. A minus sign you miss in a spec is not a ghost story. It is a mistake.

Battery numbers I actually believe

I do not trust “X days” unless the test is named. My named test is: airplane mode, light at 30 percent, a 40-megabyte scanned PDF, thirty minutes of scrolling and pinch-zoom, then a static page for thirty minutes. In HD-heavy use the static half barely sips. In A2-heavy scrolling the first half is a phone. Repeat the scrolling half three times and you have explained why a “week” died on Tuesday.

Writing on a note layer is closer to a novel if you are not scribbling the whole page every second. A stylus stroke is a small update. A page turn of a comic is a large one. Comics and manga on fast modes are another quiet killer. People buy e-ink for books and then read image-heavy files like they are on an iPad.

Vendor habits worth knowing

Boox gives you enough refresh religion to harm yourself. That is a compliment and a warning. Kindle Scribe gives you fewer knobs. You lose control and you also lose the chance to pick the worst mode by accident. reMarkable is a notebook first; PDF scroll exists, it is not the product, and I do not tune waveforms like a gamer. Supernote is similar: the company wants you to write, not to emulate a tablet browser.

If you live in PDFs, you will eventually want the knobs. If you live in books, knobs are how you spend an evening making paper look worse. Match the device to the file type before you match it to a refresh blog post.

Heat, front light, and the bag

A tablet that is busy updating feels warm in a way a Paperwhite does not. Warmth is energy that did not stay in the battery. In a bag with a folio, heat lingers and you imagine the device is “working hard.” It is. Fast refresh plus Wi-Fi plus a cloud client is how Android e-ink stops being e-ink.

I travel with airplane mode and HD for the flight PDF I already cropped at home. I do not discover the file in A2 over a European charger I forgot. The crop-at-home step reduces pans. Fewer pans beat any waveform.

A setup that does not lie about battery

Default to HD or the vendor’s quality mode for reading. Bind a fast mode to a gesture you will not hit with a palm. Full-refresh when ghosts matter. Disable auto if auto keeps you in A2 while you “just check one more page” for an hour. Dim the light. Close the file manager’s animation toys.

For annotation, I accept a slightly dirtier background rather than a mode that flashes every stroke. Flashing every stroke is how note-taking feels broken and how the controller stays busy. A dirty page you can still read is cheaper than a cinema of clean flashes.

If you need true continuous scroll, ask whether e-ink is the right panel. A cheap LCD tablet will scroll and die in hours too, but it will not pretend it is a week-long companion. Honesty about the job beats a refresh preset named after a superhero.

Dark mode, inversion, and other false savings

Inverted PDFs and dark themes on e-ink are a taste I understand at night and a refresh tax I underestimate. Flipping a page that is mostly black particles is not the same work as flipping a white page with black type, depending on the controller. I have seen inversion look “easier on the eyes” and feel worse on the battery because I kept full-refreshing to clear a milky gray. If you invert, stay on HD and stop scrubbing.

Browser reading on Android e-ink is the other trap. A web page is a PDF that never ends. Fast mode plus JavaScript plus ads is a space heater. Readability tools that produce a static article are the only web path I allow. If the page will not article-ize, I send it to a file at home. That is not purity. That is not paying twice: once in attention, once in watt-hours.

Children’s picture PDFs and slide decks are image pages. Treat them like manga. Fast mode for a flip-through, HD when you stop on a slide you will annotate. I ruined a “full day” charge on a deck I was only skimming for a logo. The logo did not need A2. I did not need to feel like I was on an iPad.

Keep a written default on a sticky note if you share the tablet. Other people discover Speed and leave it there. You inherit their waveform and their empty battery, then you write a review about cells. The setting was the cell.

The failure I now design around

The failure is not a swollen cell. It is a user who enabled A2 to make a PDF feel modern, then trusted a marketing week. I still use fast modes. I use them like a sprint. HD is the walk. PDF scrolling is the activity that quietly kills the myth. If your battery graph looks like a phone’s, check the waveform before you check the shop warranty. The panel is doing LCD work. LCD work costs LCD money, even when the screen is still e-ink in the photograph. I would rather read fewer pages cleanly than scrub a hundred pages in a mode that turns a week into a commute charger. That trade is the whole point of buying paper-like glass in the first place.