Difficulty

Very difficult

Steps

7

Time Required

                          45 minutes

Sections

1

  • Phone Battery Doubling Technique
  • 7 steps

Flags

Member-Contributed Guide

An awesome member of our community made this guide. It is not managed by iFixit staff.

  • BackPhone

  • Full Screen

  • Options

  • History

  • Save to Favorites

  • Download PDF

  • Edit

  • Translate

  • Get Shareable Link

  • Embed This Guide

  • Notify Me of Changes

  • Stop Notifications

Introduction

Notice:

Playing with Lithium-ion battery has some risk. If you don’t have the basic skill and knowledge, STOP!

Modifying Lithium batteries might violate laws in your country or region. It’s all your own responsibility!

Q: Can I mix batteries, one new and the other old?

A: Short answer: YES! Long answer: Google it.

Q: Can I do this on non-Samsung phone/battery?

A: Yes. This Samsung Galaxy S Duos / S7562 is just an example. Almost any phone, which you can cut or rebuild the back case, can load more batteries than it’s designed to.

Q: The best way to balance voltage between batteries?

A: My opinion: Discharge them to below 3.5V or use them until auto cut off. discharged battery has higher impedance and less energy, both are good for safety.

Q: What should I do when SHTF?

A: (not likely to happen if you follow this guide) Cut the wire if you have time and right tool. Drop the batt into water and step back. Inform people nearby. Do not touch the batt until it cooled off.

What you need

Step 1

              Phone Battery Doubling Technique
  • WARNING: Soft-shell lithium-ion batteries are fragile. Damaging the batteries may result in spontaneous combustion.
  • First things first. Double batteries to double the capacity. There’s no magic!

WARNING: Soft-shell lithium-ion batteries are fragile. Damaging the batteries may result in spontaneous combustion.

First things first. Double batteries to double the capacity. There’s no magic!

1024

Step 2

  • Peel skin off, but not all the way off, from ONE battery.
  • Slice some skin off from the other. both sides. Until the black plastic PCB cover and be easily removed.

Peel skin off, but not all the way off, from ONE battery.

Slice some skin off from the other. both sides. Until the black plastic PCB cover and be easily removed.

Step 3

  • Put 2 batteries together and aligned, belly to belly. Bind them with the peeled skin.
  • Not too tight!
  • Remove both black plastic PCB covers.

Put 2 batteries together and aligned, belly to belly. Bind them with the peeled skin.

Not too tight!

Remove both black plastic PCB covers.

Step 4

  • Before bridge 2 batteries together, ensure voltage difference between them less than 50mV. New batteries will very likely have about 3.9V voltage, and varies very little.
  • Bridge one B+ to anotherB+ first. Use soldering iron and solder.
  • Then, P- to P-.
  • Leave Both B- open!
  • One more WARNING! Be very careful with B- test point. DO NOT MESS WITH THEM. B- are not protected by “Protection Circuits”. Do NOT bridge B-, unless you know what you don’t know!
  • Of course. NEVER short-circuit any B- to any B+, or P- to B+, or P- to B-!

Before bridge 2 batteries together, ensure voltage difference between them less than 50mV. New batteries will very likely have about 3.9V voltage, and varies very little.

Bridge one B+ to anotherB+ first. Use soldering iron and solder.

Then, P- to P-.

Leave Both B- open!

One more WARNING! Be very careful with B- test point. DO NOT MESS WITH THEM. B- are not protected by “Protection Circuits”. Do NOT bridge B-, unless you know what you don’t know!

Of course. NEVER short-circuit any B- to any B+, or P- to B+, or P- to B-!

Step 5

  • Cut 2 notches on each plastic PCB covers. At the position of bridging wires, and faces each other. So the wires won’t lift the PCB covers.
  • These are not quite finished.
  • These are what I’m talking about.
  • Put both PCB covers back. If you bond batteries too tight, may need to loose a little bit, then tighten again later.

Cut 2 notches on each plastic PCB covers. At the position of bridging wires, and faces each other. So the wires won’t lift the PCB covers.

These are not quite finished.

These are what I’m talking about.

Put both PCB covers back. If you bond batteries too tight, may need to loose a little bit, then tighten again later.

Step 6

  • Use the skin of the peeled bat to fully bond them.
  • Cover the notches and wires with some tape. Shown PI/Kapton tape will be the best choice, anything thin enough and isolate is ok.
  • The skin is a little short for 2 cells. The exposed metal should be covered also. They are the positive terminal. You don’t wanna short-circuit something, do you? (not yet covered in these photos)

Use the skin of the peeled bat to fully bond them.

Cover the notches and wires with some tape. Shown PI/Kapton tape will be the best choice, anything thin enough and isolate is ok.

The skin is a little short for 2 cells. The exposed metal should be covered also. They are the positive terminal. You don’t wanna short-circuit something, do you? (not yet covered in these photos)

Step 7

  • Double battery vs single battery. :-P
  • The back case won’t fit double battery. Cut them the way you like.
  • (Not quite) Finished. Maybe I should 3D print some extra cover and glue it to the back case.
  • Actually I did 3D print a frame, and glued a trimmed RFID card as back cover. They work well!

Double battery vs single battery. :-P

The back case won’t fit double battery. Cut them the way you like.

(Not quite) Finished. Maybe I should 3D print some extra cover and glue it to the back case.

Actually I did 3D print a frame, and glued a trimmed RFID card as back cover. They work well!

Double power, double juice.

Cancel: I did not complete this guide.

                                                                                      106 other people completed this guide.

Author

                                      with 4 other contributors 


                    Terrance

Member since: 11/17/2009

6,193 Reputation

                                      17 Guides authored                  



                       Badges:
                       22







                                                        +19 more badges

kaandonmeztf - Dec 21, 2015

Reply

Good idea thanks :)

Inzemam Zahidi - Jan 27, 2016

Reply

Wow, i dont see pages like this anywhere else, i have a xolo phone, in india, its battery dosent have any b+/- or p+/- terminals, it just has + - and the middle one, can i wire + and - in parellel to get the doubled MAH?

jeremiah gyles - Mar 21, 2018

No no no thats is doubling the voltage and mah u just want to double mah. Because u double both and u now have a fried phone

Александр Мельников - Feb 29, 2020

In parellel, but only if two batteries are within very few mV of each other. They MUST be same mAH, or you will kill lower rated battery. First cut thin plastic or fireproof cardboard spacer, and place it between cells. Tape alined cells. Desolder top charging board from battery. Remove black plastic from top cell. Solder tabs + to +, then - to -. Nip lower black plastic, so tabs can fit under single charging board. Cover top battery tabs with tape or hot glue. Install pack same as you would single battery. Plug in phone charger. Fully charge battery pack, and enjoy. You now have a 1S2P 3.7 LiPo battery.

Удачи!

  • Александр Борисович Мельников

hakansonmezz - Feb 19, 2016

Reply

My battery hasn’t got any b+ pin under the cover. Instead, it has p+ p- and b- pins.

What should i do? Should i connect p- to p- and p+ to p+? Or mine has a different way of doubling procedure?