Danger
Potentially Dangerous
Injury may result if this procedure is not followed properly. Use caution and follow all warnings.
Danger

Introduction

Smartphones are very power hunger. Stock battery will last at most one day or less under normal usage. This guide will show how to double the battery, double time, double fun.

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!

FAQs (possibly)

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.

First thing first. Double batteries to double the capacity. There's no magic!
  • First thing first. Double batteries to double the capacity. There's no magic!

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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. 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.

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

    • Not too tight!

  • Remove both black plastic PCB covers.

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Black Friday
Broken doesn't stand a chance.
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.
  • 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-!

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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.
  • 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.

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

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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.
  • 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!

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Conclusion

Double power, double juice.

60 other people completed this guide.

Terrance

Member since: 11/17/2009

3,196 Reputation

5 Guides authored

31 Comments

Good idea thanks :)

kaandonmeztf - 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?

Inzemam Zahidi - 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?

hakansonmezz - Reply

in most Li-Ion/Li-Po batteries, B+ is P+. P- is switched by 2 N-MOSes to B-.

Terrance - Reply

No p+/- or b+/- minus indicted on each circles how can I locate the correct one

Please help. Thanks a lot.

Lloyd Edwin - Reply

how about you guys upload some photos of your batteries, if having trouble finding the right pads/pins. :-P

Terrance -

please help me find the pins :) some foto i made http://lancercz.imgur.com/all/

LancerCZ - Reply

:-S "LancerCZ's images are not publicly available"

Terrance -

It should work now :) sorry

LancerCZ -

Sorry, I can't tell exactly which pad is which. But you can always combine 2 batteries by output contacts, +to+, -to-. And remember use as few solder as possible to avoid ruin the contacts too much. These gold plated contacts are very easy to solder.

Terrance -

It looks OK but what will happen when you charge the batteries??! Is there any risk that the batteries will explode?

Also, is the charger able to charge this double battery?

Ma Ro - Reply

1. Nothing is 100.000% guaranteed 'safe'. Even stock Galaxy Note 7s explode. But if you know what u'r doing, and do it right, it will be safe enough.

2. Yes, a stock charger is able to charge double battery. It take ~2x time to charge them full.

Terrance -

Awesome! I have weekend project! Thanks for your great tutorial!

Redd Z - Reply

any feedback from people who have done this?

Lawrence S - Reply

Wonderful tutorial, what of doubling 4 pin Samsung battery

henry salvatore - Reply

for 3-pin or 4-pin batteries, only tie + and - pins. (very likely the first and the last pin. Do NOT manipulate other pins, or temperature sensing or battery ID will be ruined.

Terrance -

I did this a while back, but the phone wont regognise the higher mah and battery meter runs down as normal, when it says the battery is flat i disconect and reconnect the battery and im back to full charge. any ideas how to fix this.

I have an s3 mini running on 20 18650 li ion batterys, lasts for ever as long as i restart the phone when it says its flat.

Simon Saddler - Reply

Can i do it with lg g3 ??

zaheer abid - Reply

i saw some zero lemon batteries for g3 on the internet. of course you can. i have a long weekend so maybe ill give this a shot. i have 4pins batteries tho,

jake esguerra -

Yo thanks for the info! it's very helpful, i'll try this later. One question tho. does this work on all types of 3 pinned batteries? I have 2 batteries for my phone and i HATE charging them one at a time .Any response will be appreciated!

Jan Talape - Reply

for 3-pin or 4-pin batteries, only tie + and - pins.

Terrance -

wonderful, i have a question. if my phone stock battery is 2000mAh if i connect both battery as you showed. will my phone recognized the higher mah like 4000mAh on phone display? or it will say 2000mAh like before ?

menafa siam - Reply

if you tie P- to P-, It will still report 2Ah, and measured current consumption will be 1/2 of real value. If you tie B- to B-, it might report 4Ah, but not for sure.

Terrance -

sir if i connect 1 battery 2000 mah and other is 4000 mah of other company then what will happen

zeshan - Reply

Short answer: yes. Long answer: the 4Ah might be fake or mis-labled.

Terrance -

Awesome job done. I have a damaged Nexus 7 battery (the pbc is dead but the battery pack itself still retains charge) I'll try to bridge directly the battery ports and see it that works.

Alan W. G. Meraz - Reply

My battery has p- p+ b- , which one will i leave open? Thanks

mervin marcelino - Reply

must connect p+ to p+, and either one or both (p- to p-) and (b- to b-) works well enough. with tiny little bit technical difference.

Terrance -

Great battery.

Filbotres - Reply

Wonderful! Extended batteries are available but often pricey. For phones with removable batteries, this is a very good solution to double up multiple spare batteries and extend life/usefulness of your phone. Thanks!

coldspring21 - Reply

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