I Invent a Beast Solution for Powerbank and Mobile Charging

Hi! I have created a "beast" of a solution for power banks and mobile batteries that is actually working successfully.

The biggest benefit is that I can charge it very easily. But how? By charging the phone? No. Then how? By charging the phone's back cover.

It sounds a bit strange to hear, right? But I have done something to my phone’s cover that makes it act like a power bank. I have attached a battery to the back of it. Now, I don’t have to charge the phone; I just have to charge the cover. Basically, I don’t need to shove a charger cable into the phone anymore. I just put the cover on charge, and I can still use my phone freely.

When my phone battery starts getting low, the cover will already be fully charged. I just snap the cover on, and it charges the phone’s battery. This means I don't need to be stuck to a wall charger or deal with connecting cables.

You might be thinking: How does the cover actually charge the phone? Is it wireless? Or maybe a short Type-C to Type-C cable?

Here is the answer:

It is not wireless charging, because wireless charging makes the back of the phone get very hot, which reduces battery life and lowers efficiency significantly. So, I rejected the wireless concept.

It is not via cable either, because I hate using a phone with a cable plugged in. The cable keeps disconnecting, and it’s annoying/irritating to hold the phone.

So, I thought: Why not charge the phone directly—battery to battery?

I opened the back of my phone, took wires out from the battery terminals, and brought them out to the back of the phone. Now, these terminals are connected to the battery. If I charge this, it is a direct battery connection, which is very efficient.

Secondly, when I attach the cover’s battery to this, the phone battery receives pure DC voltage, allowing it to charge very smoothly and safely.

The biggest benefit—and I have to say, this is a beast feature—is that when I put a heavy load on the phone (like gaming), the phone battery automatically starts drawing power faster from the cover. As soon as I put the phone down and the load decreases, the charging speed slows down.

Other Benefits:

No need for wireless charging.

No fear of the phone battery heating up.

No irritation of being tethered to a charger.

Battery Life: You might worry that this will reduce the phone’s battery life. It won’t. In fact, it will likely increase it because the cycle count stays lower. It’s just the cover battery that takes the hit, and replacing that is 4x cheaper than replacing the internal phone battery.

The Module: I also attached a small power bank module to the cover battery. It allows you to charge the cover using your standard phone charger. Despite being small, it supports 22.5W fast charging, so you can even use this cover to charge a completely different phone if you want.

The Cons:

Now, you might be thinking, "There are so many benefits, but like everything, there must be some downsides." Yes, there are some cons I need to tell you about:

It won't charge to 100%: It will keep the phone battery between 30% and 50%. As soon as the battery hits 50%, the cover stops charging to save its own capacity. However, if you start using the phone heavily, the cover will start releasing energy again. You can decide if this is good or bad, but in my opinion, it is good because the battery stays in the middle range, which reduces cycle counts.

Percentage Reading: If you charge the phone via the cover, the mobile software might show you the wrong battery percentage. The phone doesn't "know" you are feeding it power from the outside. To fix this, you have to charge the phone fully with a cable overnight at least once so the calibration stays correct.

Usage Timing: You can only attach the cover when the phone is below 50%. If your phone is at 100% and you attach it, there is no benefit; energy will just be wasted.

Two Covers Required: You will need two covers. When you don't need the battery cover, you must swap to a normal cover. This is to ensure the exposed battery terminals on the back of the phone don't short out by touching keys or metal objects in your pocket.

So, honestly, those are the only cons I found. But everything has some downsides!

Please Note:

"Please Note that I did not purchase these parts from Amazon myself, as it is not available in my country. However, I have found the exact same components on Amazon and listed them here for your convenience."

"A Quick Note on Photos: Since I was using my only phone to build and document this project, I couldn't take photos of some internal steps while the phone was disassembled. I didn't have another camera available at the time. I've tried my best to explain those steps clearly in text. If you find any part confusing or need a live look at the setup, feel free to book a 1-on-1 call or My Whatsapp Channel with me, and I’ll be happy to guide you!"

Components

1. 1x 22.5w Fast charging Module
2. 1x 3.85V Lipo Battery 5000mAh Rechargeable Lithium ion
3. Copper Wire 27AWG (Need Approx 2 Foot Only)
4. 4xNickel Strip 99.6% Nickel, 2 Inches Nickel Strips, 0.15x6x50mm (Need Approx 4 Strips Only)

1. dubble sided Tape
2. Super Glue
3. Glue gun Sticks

"If you have specific questions or get stuck on your every project, you can easily book a 1-on-1 online troubleshooting call with me. I will do my absolute best to help you solve the issue.

Please note that this is a paid service where you pay for my time. However, my policy is simple: If I can solve your problem or point you in the right direction, you pay for the session. If I cannot guide you or find a solution, I will issue a full refund. You only pay for results."

[Link to 1-on-1 online troubleshooting call]

Planning the Layout

First, take your phone's back cover (case). Place the external battery and the Power Bank module on the back of the case to see where they fit best. Do not glue anything yet. We just need a rough idea of the placement. You can adjust it according to your preference or check my photos to see how I arranged mine.

Step 2: Internal Connections

Now, open your phone's back panel.

1. Your task is to solder small pieces of copper wire to the phone's internal battery terminals.
2. Important: You must use 27AWG copper wire. I chose this specific size to maintain the correct resistance—not too thick, not too thin.
3. Once soldered, route the wires outside and close the phone's back panel.
4. Mark the Polarity: Clearly mark which wire is Positive (+) and which is Negative (-).
5. Safety Warning: Be very careful not to scrape off the wire’s insulation coating, as this could cause a short circuit. You can use tape to cover them for extra safety.

Step 3: Creating External Terminals

Now that the battery wires are outside the phone:

1. Use a blade to gently scrape the edges of the copper wires to remove the enamel coating. This ensures the solder will stick.
2. Take a Nickel Strip and solder it to the ends of these copper wires. Make sure the Positive and Negative wires do not touch each other.
3. Use double-sided tape to stick these new terminals flat against the back of the phone.

Step 4: Preparing the Phone Case

Now we need to transfer these connection points to the phone case.

1. Apply a little bit of solder paste (or something that leaves a mark) onto the terminals you just attached to the phone.
2. Put the phone case back on, press it gently, and then remove it. You will see a mark/imprint on the inside of the case.
3. Use a hot soldering iron to make small holes exactly where the marks are.
4. Pass the copper wires through these holes so they come out to the back of the case.
5. Take two more nickel strips, attach them to the copper wires, and secure them to the outside of the case using super glue.

Step 5: Connecting the External Battery

Put the back cover onto the phone. You should now have two connection points accessible from the outside.

1. Scrape the coating off the copper wires again if needed.
2. Check Polarity: Use a multimeter to double-check which wire is Positive (+) and which is Negative (-). Mark them clearly.
3. Take your external battery and solder the wires:
4. Connect the Phone's Positive (+) wire to the External Battery's Positive (+).
5. Connect the Phone's Negative (-) wire to the External Battery's Negative (-).

Step 6: Adding the Power Bank Module

Finally, let's connect the charging module.

1. Note: For this connection, do not use the thin copper wire. Use thicker, standard wires.
2. Solder two wires to the external battery terminals.
3. Connect these wires to the Power Bank Module:
4. Battery Positive (+) to Module Positive (+).
5. Battery Negative (-) to Module Negative (-).
6. Cover all exposed wires with electrical tape to prevent short circuits.
7. Use a Glue Gun to securely stick the external battery and the module to the back of the phone case.

That’s it! Your DIY Power Bank Case is ready.