Power an Android Phone Without Battery

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Introduction: Power an Android Phone Without Battery

This idea came to me when I built another project

For my needs, I had to have an Android alaways on but I didn't want to let it pluged on a wall with the battery cell inside. A battery that is 24/7 on charge can be damaged and start a fire ! So I wanted to bring power from a wall plug, directly in the phone.

Be careful ! Here we will play with electricity and battery cell. Those elements can be dangerous if you don't know what you're doing. I can't be responsible of any damage caused on your equipmentor on yourself. So please, read every documentation you can found BEFORE starting anything !

Step 1: What Numbers Said

For this project, I use an "old" Samsung Galaxy S3. Numbers I'll give will just be correct with this model. Please check on your device the values you are looking for.

When I removed the battery cell of my device, I found a little label that said the device should be powerd at 3.8V. I found the same number wrote on the battery cell. But when I looked on the power plug, I saw it dispense 5.0V. We will need to reduce this voltage in order to not damage the device.

We can see on the device four little pins. Two of them are the +/- poles to power the device. To know exacly which one does what, you can look on the battery cell. It should be + and - symbols in front of the right ones.

Step 2: Gathering Parts for Assembly

First of all, we will need cable between the power plug and the device. Took an old USB -> micro-USB and remove the micro-USB head.

If you remove the plastic protection you will see multiple wire. We only need two of them : the red one and the black one.

Here comes the hardest part. In order to make a good contact between our wires and the pins on device we will use a part of the battery cell itself.

With thousand precautions, you can start to remove the plastic sheet protection around the battery cell. You will expose the part we need : the one with four contacts. On my model, this part was protected with a little piece of plastic that I removed with a small pliers. With a small blade, you can detach this little part. See pictures to spot it.

Step 3: Welding Parts

Using all those parts, if I measure output voltage I found 4.83V (don't mind the Arduino, it's not even plugged). It's less than the 5.0 wrote on the battery cell but it is still a bit high and it can damaged the device.

You will have to weld the red and black wires on the little battery cell part. The cell itself can be use as reminder to know where plugged which wire.

After all of that, the output voltage is still a bit high but it will do the thing.

Step 4: Power the Device

Ok, now you just have to put your assembly into your device. For my part, I used a small piece of cardboard to hold our it in front of the four pins.

Hold your breath and... Yay ! The device starts \o/ !

Thanks to the Ampere app, you can control the device input voltage. On mine, it displays 4.2V. It's a bit high but I don't think it will damage my device.

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    37 Comments

    0
    raymondday61
    raymondday61

    3 months ago

    This works but after time the phone will still turn off. I guess it times the battery that it thinks it has even though the volts don't go down and it will turn off. I guess need a power supply that goes down some volts and back up like a battery would. Seems like no one got this to work so a phone will stay up for like years on a power suppy.

    0
    raymondday61
    raymondday61

    Answer 3 months ago

    There are ways a little transformer. 2 insulated wires a magnetic field between them to step down the power.

    Or can use a transistor to turn the power off and on fast with a capacitor Charge up the static in the capacitor just some till it get's to the right volts.

    0
    Adam_is_stupid
    Adam_is_stupid

    Answer 1 year ago

    you can use a resistor

    0
    Rodribs
    Rodribs

    Question 9 months ago

    Hello there, just to be clear, took BMS circuit off the li-on battery and soldered ground and Vcc directly to B+ B- and then just powered on the phone? Regards

    0
    BanditQ
    BanditQ

    Question 1 year ago

    Great idea for a spare phone at home that does not need mobility as a feature - that is exactly why I would want to do it. An extra phone running Apps I use watching TV or working at my laptop. I would the run less apps on my primary phone if I could do this!
    Has anyone tried it on their Samsung Android ROM version and were there any disadvantages ?

    Some reading on the web suggests laptops power switches in parallel (battery/DC power charger) which is why they run just fine without a battery, and the design for MOST smartphone is a series connect (battery+DC power) hence the need to connect something to where the removable battery connectors. Obviously you need a phone model with removable battery (eg older Samsung models). Does what I read sound right?

    More reading on "Dr Google" suggested that peek current (Amp spike) may not be sufficient with just a standard usb charger DC supply connected to the battery terminals. I am not sure if this was meaning your typical 5V 500mA charger - most Samsung chargers like one used in this Instructable are 1A is that accurate?

    The "peek use", typically at power on, is worth testing with a 500mA charger. For me, that second phone might be plugged into laptop port (=500mA), or I want to plug it in to the closest standard USB charger I have available which is not always the Samsung supplied charger (1A). The usage at home will typically be WIFI connected, and streaming with a Chromecast; or an extra skype voice call; so this is probably low chance of hitting peek (I assume). Would a peek use case be one or all of the following: phone call using mobile network (assuming available); screen casting (mirroring) your screen and then watching stream content (e.g. Youtube); Whatsapp/Skype/(any other VOIP app) video call with phone brightness on full. It would be interesting to know if phone would keep running under these conditions. I am basing these examples on times my phone battery could not cope.

    0
    cristian.sto97
    cristian.sto97

    Answer 1 year ago

    having done some testing with a nexus 5. I`ve seen it go up to 2A in benchmarks. I`ve got some capacitors in parallel to compensate for big spikes, but a good power supply is still needed.

    0
    manta10
    manta10

    1 year ago

    My friend suggested another solution to this problem.

    He just wired another cell phone battery to pins in the battery compartment, charging it via standard micro usb connector, so no need for Arduino or step-down converter.

    So frankly speaking I am looking for an adapter to let me use any 3.7V ion cell battery for any smartphone ( outside or inside mounted).

    Let me know your opinion

    jack
    manta103g@gmail.com

    0
    cristian.sto97
    cristian.sto97

    Reply 1 year ago

    the battery will die within a year if it`s always plugged in

    0
    Rahul Ramachandran
    Rahul Ramachandran

    Question 1 year ago

    Need some help with sony xperia z2. I want to connect to power directly but the connections are complicated. Please advise

    20200520_142650.jpg20200520_141319.jpg
    0
    cristian.sto97
    cristian.sto97

    Answer 1 year ago

    measure the pins, see what`s positive and negative. Try if it works. Please don`t plug it straight to 5v tho. Only luck will save it

    0
    Mordog89
    Mordog89

    1 year ago

    I added a DC-DC voltage pull down regulator after a 5V 2A wall wart, I did this project on the S3 as well, nice to see them live on. I use it as a baby monitor and have fried 2 batteries as it's always plugged in. Did resuse the battery part as well but soldered it on with some wires instead of the cardboard solution. Then I hotclued it all in the batteri compartment for nice rigidity. Did try a few things but found the obly thing that this setup cannot handle is to use the camera with the flash enabled as 2A is apparently not enough when it goes full brightness!

    0
    IHThisun
    IHThisun

    1 year ago

    Hello.. Can anyone tell me how to set the device to turn on automatically when I connect it to the external power source?

    (It is a Samsung Note 3 (rooted) and everything went well.. I didn't attach the circuit strip salvaged from the battery.. just connected to a 5V USB port.. No over heating issues by the way.. Now I can turn on the device with external power but manually.. I want it to automatically turn on when I connect it to the external power source.. please help.. 🙏

    Edit -

    Another problem.. ☹️ When I turn on the device it shows 100% battery.. (because external power source is higher than 4.4V right?) But after about 30 minutes, the battery percentage starts to decrease gradually.. how can it be?

    Screenshot_2020-05-20-22-25-03.png
    0
    ibshalaby
    ibshalaby

    Reply 1 year ago

    Dear Sir,
    I need to do exactly the same. I want to use this technique to make a car tracker using my old note 3 phone. Should you reach a workable way please forward to me to do the same.

    0
    brianelete
    brianelete

    Question 1 year ago

    Can I reroute the power from the USB in to power the device instead of charge the (not existent) battery? The device needs 3.7V and not 5V that comes from the USB, but the device is already doing in internally when you have a regular phone with battery. So can you just add some wires inside the phone and use it with a regular USB cable plugged into the USB of the phone and have no battery?

    0
    ArthurB24
    ArthurB24

    Answer 1 year ago

    This is a very good question but I really have no clue about the answer. If you want to try it, please let me know, I would be glad to read about it !

    0
    brianelete
    brianelete

    Reply 1 year ago

    Hey, thanks for the reply, unfortunately I lack the technical skills and tools. I have some old phones I wanted to use without battery. I managed to turn one on for a couple of seconds by directly pressing the red and black cables of the cut in half USB cable but I could not hold them in place and didn't wanted to fry the device either. I hope someone with the right skills try this method. (Or I learn the skills :D)

    0
    frfoor99999
    frfoor99999

    Question 1 year ago

    can you use mhl hdmi after you plug power directily to pins? cuz mhl give power also to phone charger so it would be two powersources in one phone.
    ??????

    0
    ArthurB24
    ArthurB24

    Answer 1 year ago

    Honestly, I have no idea :(
    But if you can get an answer, I will be happy to read it here !