Triple the Battery Life of Kindle Paperwhite!

This modification swaps out the battery of an 11th gen Kindle Paperwhite for one with 3.3x the capacity. Imagine how much more reading you could do between charges!

This requires the new battery, a custom flexible cable for that battery, and a new 3D-printed enclosure with more space to accommodate the larger battery.

Because the new enclosure is too think for the cases on the market, I designed the back with elastic straps that make the Kindle easy to hold. You don't get screen protection, but that isn't very important to me. Comfort was the goal and I think this works well.

Some disclaimers:

• This will void your warranty
• It is possible to damage/brick your Kindle
• Lithium batteries can be dangerous
• The Kindle won't be waterproof anymore

• 5000mAh lithium battery
• 3D-printed enclosure back (resin printing is ideal)
• Spray paint
• Custom flexible PCB
• Hirose BM22L-6P-V(51) - best to get extras in case of goofs
• 100k ohm 0805 SMD resistor
• 0.5" wide stretchy straps
• E6000 adhesive

You don't need many tools, but I suggest:

• Trim removal tools (to take apart Kindle and to remove original battery)
• Heavy duty clips to hold straps together while glue dries
• SMD soldering equipment (a hot plate is easier than hot air, in my opinion)

The enclosure back snaps on, but it can be pretty difficult to remove.

I recommend using something like automotive trim removal tools for this.

This video does a good job explaining how to do it: https://youtu.be/BTJdqxAj6f8?si=ghDpumRHBG8YgaRV

Then you'll need to take out the battery. Just pull up on the cable to disconnect it from the main board. A few drops of Goof Off will help loosen the adhesive that holds down the battery. You can also use a hair dryer. Then carefully lift up the edges of the battery and pull it out.

Be careful! It is really easy to damage the battery, so don't use much prying force.

You can use a service like PCBWay or JLCPCB to order both the flexible PCB and the 3D-printed back.

You can download a zip folder with the PCB Gerber files here: https://drive.google.com/file/d/1nERR9D10YGXPYdFIDkBR5zEoBJEApCEY/view?usp=sharing

I've provided the files and you just need to upload them, then place your order. You don't need to do anything special with the order—the standard options are fine. I recommend ordering a handful of the PCBs and a couple of the 3D-printed backs, in case you damage something.

The resistor is a standard 0805 SMD resistor in 100k ohm. That makes the Kindle think that it is receiving a signal from the thermistor at room temperature. This is only okay because the battery has its own built-in protection.

If you don't order the battery I linked to, you'll need to make sure you find one with the same dimensions and that also has built-in protection (thermal, over-current, short circuit, etc.).

The hardest part to find is the connector. It is a Hirose BM22L-6P-V(51) (the "male" side). The only place I was able to find it available in low quantities was on AliExpress. Make sure you order the correct part number! I recommend getting a pack of them, because they're easy to accidentally damage.

This is the hardest step. You need to solder the Hirose connector and the SMD resistor onto the flexible PCB.

Connector orientation matters!

It can be hard to see with the naked eye, but the Hirose connector can only fit one way. You have to make sure that it is in the correct orientation. You should see that the inner cavity is offset a bit. Make sure it matches up with the connector on the Kindle mainboard properly.

I recommend soldering use a hot plate, rather than hot air. Use lots of flux, but only use a tiny bit of solder paste for the connector to avoid bridging. The resistor is much easier and doesn't need any special treatment.

The cut the battery cable to length and solder them to the big pads, marked positive (red) and negative (black).

The PCB has a place for a second "ID" resistor. Nothing should be connected to that—it is only there in case I discover in the future that I need it.

There are tons of spraypainting tutorials out there, so I won't go into too much detail.

You can paint the 3D-printed enclosure back however you like. I recommend a good base of sandable primer. Sand that and add coats until you have a nice, smooth finish.

Then add your spray paint color of choice. Once again, many iterations of sanding and repainting will yield the best results. By the end, you should probably be wet sanding with 2500+ grit. Then do the same with a clear coat if you want.

Once you paint looks good and is dry, you can add the straps. Feed them through the slots and add some adhesive (I like E6000). Pull them taut so they're nice and snappy. Then use strong clips to hold them in place until the glue dries. After, trim the excess strap. The straps should fit nice and flat within the channels.

The final step is to attach the power button and LED light tube. The power button is easy: just put the flexible bits into the T-shape holder bits. The light tube will probably require a dab of glue to hold it in place.

Carefully snap the back onto the Kindle and you're done!

You can charge it just like you normally would. The battery level percentage should be accurate, since the new battery runs at voltages similar to the original.

Now you can read for three times longer before you need to charge again, woo!