Turbo kobo

Disclaimer: Following these instructions will void your warranty in a spectacular way.

Part 1: Disassembly and Discoveries

This morning my kobo glo eBook reader died on me 🙁 The symptoms were refusing to charge its battery even after extended periods under external power and only running at all when external power was provided. Also rebooting when hooked up. This is a better opportunity than most to take a peek inside. The first step was to hit youtube for a disassembly video:

From the video I learned at which corner to start cracking the enclosure, if not much more. It was time to break out the highly specialized tools an get to the job at hand.

Highly specialized tools

Yup, that is a cocktail pick. And a toothpick.

Once inside, I found the battery and a pleasant surprise: A micro SD card! Looks like kobo decided against soldering flash memory to their main boards and went the hacker friendly way instead.

The battery turned out to be the expected LiPo pack dominating the design. It comes with a small circuit board attached wich I figured to be either the battery protection circuitry or an integrated charger.

Aaaand open!

The SD card is circled in red. The battery is labeled ‘Battery’ to avoid confusion.

I concluded that the failure to charge may have three possible reasons:

  1. The LiPo cell might be dead
  2. The circuitry that is attached to the cell has failed
  3. There is a charging circuit on the main board that is blown

With two of three possible fails being addressable with the same solution, namely getting a replacement battery, I decided to go for it. That turned out to be harder than expected and my expedition to the local electronic parts dealer netted me a nice 8 GB micro SD card but no new battery. So I turned to eBay which got me insights and ideas. From the product pictures on eBay I could deduce that the circuit board merely is there for battery protection and is no integrated charger. And secondly: Why just replace the old battery when I can expand it? This was where I decided to cross the border between repairing and hacking. The battery I finally ordered has almost the same footprint as the old one but 1.8 times the capacity (2200 mAh vs. 1200 mAh). Of course it’s about twice as thick as the original, but I’ll deal with that later. Note: You don’t have to go this way if you just want to repair your kobo. You can get 1200 mAh batteries that fit into the enclosure on ebay. Cramming in the larger battery comes with its own set of problems and you may not find it worth the marginal benefits.

Remember that talk about micro SD cards earlier? The surprises didn’t end with the original card being there. To really put the turbo into the kobo I want to upgrade its internal storage capacity. So I turned to copying the kobo SD card to the larger one I had bought and then resize the data partition. While going on about this, I used gparted to inspect the original card as well.

parted GUI for the coddled generation

I sense an opportunity here.

To the right you see gparted working on the original SD card. I found that almost half of it is unallocated. Because you should perform one fix at a time to keep track where the fail happens, I want to wait for the battery to arrive and try it out with the original SD card in place. If that works, I will swap the SD card with the larger one I purchased, to see if that expansion works as well.

And if all that turns out fine, I will see if resizing the data partition of the original card is a viable zero cost way to double your kobo’s storage.

Part 2: Parts and Problems


Not really a similar footprint.

So the new battery has arrived in the mail and I found that the footprint istn’t as similar to the old one as I had assumed. But the width seemed to fit well enough so I went with it. The first step was to transplant the connector for the old battery to the new one. That was pretty straight forward soldering and I even managed to keep some of the original Kapton tape intact.

With that done I hooked up the battery to the main board and booted the device. Then I had to euphorically twitter the result and perform a little dance: It actually worked! I was completely stoked.

Now it was time to try out the SD card swap. It went flawlessly, my new larger one as well as the resized original card.

Loads of storage

I need more books

It was clear that the new battery would never fit into the case. I hoped that cutting a battery shaped hole into the back panel would let the new part sit flush with the outside of the enclosure and I could cover it all up with gaffer tape, but it turned out to protrude much farther from the back than I had anticipated. The second idea to hide the bulge was to just put the reader in its cover where it is held in place by four brackets, one in each corner. This seemed to work but the constant pressure on the back of the display led to the touchscreen being inresponsive. This was bad from an ergonomics standpoint and had to be remedied. The solution was to remove a layer of felt and some plastic from the decorative cover.

There goes me secret stash

The modified kobo, its cover and some of the removed material.


With the hacked up back cover there still is a slight bulge but the device works and I didn’t have to cut all the way through the cover so the new battery isn’t obvious from the outside. I appreciate this, because not having to explain at the airport what’s going on with my electronics is something I really like. I assume that the device looks fairly normal to an x-ray machine.

Part 3: Conclusions and Considerations

Both modifications to the reader don’t really make much sense and I’m the first to admit that. The battery life with the original 1200 mAh cell was perfectly fine and the only advantage I get from the larger battery is that I have to worry a bit less whether I have forgotten to switch off the backlight when reading outside. And the added 6 GB of memory are just ridiculous, considering I hadn’t gotten near the original capacity of around 1 GB. So I mostly improved the device in metrics that don’t really matter and hacked up the enclosure in the process.

Was it worth it? Well the kobo now looks like a hacked together piece of crap but it is now MY hacked together piece of crap 🙂 Fixing and modding your devices gives you a whole new sense of ownership and I think my ‘new’ kobo rocks. Also I have found a way to double a kobo’s capacity for free by simply resizing the ‘KOBOeReader’ partition on the original micro SD card. Sure, one could just pop a new card into the reader’s expansion slot, but where’s the fun in that?

I’m still wondering why the original micro SD card has had so much unallocated space. One theory is that this had been done to avoid data corruption by having loads of flash memory to account for read/ write cycles. This is unlikely though, since the way these devices are used doesn’t result in a high number of r/w cycles. And longevity usually isn’t a consideration in consumer electronics design. The much more likely theory is that they had used 2 GB cards in prototyping and then found 4GB cards to be cheaper when the reader went into production. This may as well have happend later in the production cycle, so there may be devices with 2 GB cards out there that can not be easily upgraded.