Replacing Kobo Touch Battery

by Ima Pseudonym

43K1626

Intro: Replacing Kobo Touch Battery

Intro

Over the course of a couple of months the battery life of my Kobo Touch started to deteriorate noticeably. Until it suddenly wouldn't start or charge anymore at all. Connecting it to the computer produced some response from the light, it would seem like the Kobo tried to start but then failed due to insufficient battery capacity or something. The screen never even flickered and my computer would not recognize the Kobo as being connected.

As I was sure no mechanical harm had happened to the device (I hadn't taken it anywhere in months), I figured it had to be that battery that gave out. So I set out trying to find out how to replace it, and figuring this out turned out to be a lot harder than expected. Googling just yields a lot of forum threads complaining about the bad practice of not putting user-replaceable batteries in devices like this (the term 'planned obsolence' comes along very often). I found one (Dutch) forum thread on someone dealing with the same problem I had, in the end he mentioned he just ordered a generic three-lead battery from 'the internet' but never responded to my question which battery this was. In reply to him, someone mentioned that he was lucky that the third lead on the battery he found matched up to what the kobo expected, and that it was a safer bet to just stick a new battery on the old battery's connection board. So this is what I did, and to save you the pain of figuring this all out yourself I will show you what I've done here in my first Instructable ever.

What you'll need

Soldering iron. I think any soldering iron will do, I got one of the cheapest ones available on Aliexpress, and it came including a stand, tweezers, soldering tin. Search for one yourself, or get the on I got here. The tweezers aren't a must

Soldering skills. Optional. No really, this project is the first time I've held a soldering iron since I was 14. You just need to know which end of the soldering iron gets hot, and then hold that end against whatever you want to (de)solder. The connections you'll be working with are pretty big, so it's easy work. If you want to, you can probably find tutorials on YouTube.

Desoldering braid. You can use this copper braid to suck op soldering tin when you want to desolder a connection. You cut off a piece of the braid, put in on the connection you want to desolder, then press it with your hot soldering iron until you feel the solder melting and being sucked up by the braid. I used this.

New battery. You'll need a new battery (duh!). More importantly, you'll need a LiPo battery of the same size as the one that's in your Kobo right now. I first tried to do this by measuring the size of the battery holder, and ordering a battery based on those measurements. That failed as, even though my Kindle now worked, I couldn't replace the back cover anymore. Then I figured out that the numbered code on the battery (see picture, I had unfortunately torn of the wrapper from the battery before making a picture) isn't just a product number, it's the size of the battery. In this case the numbers are 404252, meaning that this battery is 4.0 mm thick and 42 by 52 mm long/wide. And just this number code turned out the best way to find a new battery of exactly the right size, in the end I ordered this one and it works great. Check the number on your old battery to be sure!

STEP 1: Opening Up the Kobo Touch and Removing the Old Battery

Opening up the Kobo Touch is pretty easy. Looking at the picture that I took from TechCrunch's review on this device, you can see a crack running around the backside. Pressing on this crack and prying a nail behind the back cover, you can separate the back cover from the bezel and the internals. Look at this YouTube video to see someone doing this.

This will give you a view of the main PCB board, and will clearly show you the battery and the connector connecting the battery with the board. The battery is glued in the holder, so you will need some force to remove it, do this as follows:

  • Start by disconnecting the battery. In the image, the connector is marked. Disconnect it by taking hold of the wires right where they leave the connector and gently pull them away from the board. In this case "away from the board" means that, assuming your Kobo is lying screen-down on a table, you'll pull gently upwards (away from the table). This will disconnect the battery, but it's still glued to the battery holder. The best way to get the battery out is to take a screwdriver, or anything else that can function as a lever, pry it below the edge of the battery and carefully try to lever it out, using the edge of the battery holder as a pivot point for your screwdriver. Do this in multiple locations and never apply a lot of force (you don't want to damage the screen below) and the battery should come out eventually.

STEP 2: Retrieving the Connector From the Battery

Time to 'unwrap' your battery. Take off at least the top part of the black wrapping around your battery. This should be easy and will reveal a metallic battery cell with black isolating tape around the top edge (where the wires come out). This tape needs to come off as well, but be carefull not to damage the small board beneath it, we'll need it later.

The small board contains two connections for the positive and negative battery terminals, it also contains an NTC. Probably, this serves to measure battery temperature to prevent the battery from overheating. And presumably, this is what the third wire in the connector is for. This means that the Kobo expects the NTC to be at the other end of this wire, so in replacing the battery you have two options: either find a general LiPo battery and stick this connection board on it, or find another three-wire LiPo battery that also has an NTC. I failed finding another three-wire battery (not counting the one that cost $25 plus $90 shipping costs), so I went with sticking this board on a new battery.

To retrieve the board from the battery, take off the isolating foam strip. This will reveal the battery terminals, desolder the connections between the battery and the board.

STEP 3: Solder Connection Board to New Battery

My new battery came looking like this, it has its own connection board with just two connection wires (and no NTC). This board needs to come off. So: take off the tape, straighten out the battery terminals (they were folded in my case), and desolder the connections between the battery terminals and the connection board. Keep in which terminal was connected to B+ and B- on the board, as you'll need to connect them to the same places on the board that came from your Kobo.

Solder the Kobo connection board to this new battery. In my case, the battery terminals and the connections on the Kobo connection board weren't evenly spaced. This meant that I had to ben one of the battery terminals slightly to make it line up. This introduced a new problem though, due to this misalignment, part of the terminal would contact the connections of the the wires to the board, causing a short-circuit. To prevent this, I used some electrical tape to insulate the battery terminal, solving this problem.

STEP 4: Connect New Battery

Put the new battery in the battery holder, it will probably stick slightly to the glue residues that are still in there. Make sure the connection board fits in there as well, and has the connection cables on the side of the recess in the battery holder.

Reconnect the battery connection cable. Replace the back cover. Success!

Note: In my case, the e-reader initially wouldn't turn on. However, after connecting it to a computer it turned on almost straight away. After that, turning it on, off or in standby is no problem and starts again every time without having to connect it to a computer first.

18 Comments

yauhen 6 months ago

Hi! thanks for instructable! I lost my old battery. Сan you measure the resistance between the black and white pin? Thank you very much!

yauhen 6 months ago

ok, thanks for answer

Tom van Weerd 1 year ago

Because of an incorrect software upgrade (blame Kobo) my Kobo glo is dead. I suspect that the OS is on a small sd card (2GB). Does anyone know if this correct and if so where can I get a working card?

fla_2 5 years ago

Thanks for this very useful instructable. Searching for "1000mAh Battery For kobo N905B 404355" on aliexpress found a perfect replacement for my kobo touch. Since the old and new batteries both had two wire connectors I did not transfer the small board between batteries as you did. The kobo now charges to 100% but drops immediately to around 50% when unplugged. Don't know if the kobo will learn the discharge pattern of the new battery+small board and display more accurate percentages after a few charge/discharge cycles.

Jéremboo 2 years ago

I've got the same issue for my Kobo Aura H2O - N250. I replaced the battery with the model needed for that one (SP305590, 1500mAh, 90x55x3.0mm) found in AliExpress (https://fr.aliexpress.com/item/4001084928419.html?...).
But once the kobo is plugged, it directly jumps to 100% and immediately drops to the initial state of the battery (for me 70%-68%) when unpluged... I've tested to buy another battery from another shop with the same result. Don't know from where comes the issue then...

Ima Pseudonym 5 years ago

Nice to know this was of use to you!
Please report back on whether the Kobo catches up with the new battery. Might be useful for others to know.

fla_2 4 years ago

The battery completely died very quickly and won't recharge. Not sure if the new battery was defective or what but I'm not investing more time/money on this old kobo touch.

thakurswati16392 3 years ago

My Kobo touch-super old but barely used, has given way. Read this article, and opened it up. The battery looks curved (the images and videos I saw online show a flat battery). I assume thats causing the dead screen. Now, I need the same battery-404252, but that doesn't seem to be available-would another 3V battery (like a 402535?) work?

Ima Pseudonym 3 years ago

From what I remember those numbers show the dimensions of the battery in millimeters as thickness (x10), width, length. So, for the original: 4.0 mm thick, 42 mm wide, 52 mm long.
I'd assume (!!) that another 3V battery would also work, but it needs to fit within the space for the original battery. From the numbers, the alternative you suggest would be equally thick but significantly narrower and shorter. I'd imagine that would mean your Kobo will last less long on a single charge than it did with the original battery.

ThiagoM72 5 years ago

Hello, I have a Kobo Glo and his battery has only the positive and negative, does not have the NTC. Do you think it would be a problem I just did not connect the NTC?

Ima Pseudonym 5 years ago

I just transferred the connection board from the old battery to the new one, taking along the NTC.

If your old battery's connection board doesn't have an NTC, the Kobo probably won't miss it if the new one doesn't have it either. So probably there won't be much difference between leaving the connection board on the new battery and using that, or transferring the old one.

Proceed at your own risk though... ;)

kbot01 6 years ago

My kobo glo kept freezing up...after some trouble-shooting...I found it works as normal if I have it plugged into a power socket. I also have a power bank, so while it is awkward, I can have assurance for something when out there.

ereader3 6 years ago

My Kobo touch was running fine then I had it in a bag at the beach and when I turned it on later there was a dark line running down the screen. I could still read my books fine just this silly line was there. So I thought it was sand in it so I took off the back cover, blew around the edges, loosened the screws but thought better of it, and final put it all back together. Now the screen is white! Light at top can go from blue to green and all combinations, occasionally red-as I muck around connecting to PC or switching on and off etc. I've tried resetting and factory resetting. One thing I notice is that it is really hot around the front of micro usb port and slightly to the left of that i.e. on the bottom of the reading screen and surrounding edge. Is there anything I can do to get my ereader going again?

CyberR1 6 years ago

Hey buddy,
you might wanna see if you accidentally broke the screen. For reference on how to know if the screen is broken you can follow some of these threads https://www.mobileread.com/forums/showthread.php?t=291177https://www.mobileread.com/forums/showthread.php?t=255415 . If you have actually broken the screen, then only way to get it going is to buy a screen replacement and changing it(if ya wanna do it yourself), if its in warranty take it to the nearest kobo service center fast.

estxgran2 7 years ago

any thoughts on repairing the volume on a Kindle HDX7? Mine is about 3-4years old...it's my refurbished second one to own, and although I do have a sound booster installed, I've never had it above the 40 rating they warned me about.

Thanks for any thoughts on this.

Ima Pseudonym 7 years ago

As an addition to my previous reply, look at here: https://nl.ifixit.com/Teardown/Kindle+Fire+HDX+7-I...

That page contains pictures of a teardown from the HDX7. In step 5 they mention that volume buttons and audio jack should be easily replaceable. In step 10 they have an image of the motherboard, showing where the audio chips are (one amplifier, one for the codec). If either of those is broken, I don't think you'll be able to replace that.

Ima Pseudonym 7 years ago

Hi estxgran2!

I'm sorry, but I don't know anything about the HDX7. If it's a broken sound-chip or something of the sort, I'm going to assume it's integrated into the main board of the device and will be (near) impossible to replace.

If it's the audiojack or a speaker (connection) that is faulty, that may be replaceable but then the challenge is to find out which replacement parts are suitable.

Sorry I can't really help you with this!