I made this for my next project.


How to connect phones with 4 pins, take a look into comments.

Step 1: "Battery"

I took pins from SD card adapter and glue them with Super Attak glue on piece of wood.

I used 82kΩ resistor.

Step 2: Power Supply

After couple of months I can say this is perfect power supply. It has enough power and it does not go hot! I bought it on Ebay for some bucks

Lithium Charger Step down 5A 5V-32V to 0.8V-30V Power Supply Module LED Drive 5A


<p>what should be the minimum volts and amps to power the power supply model</p>
<p>Hi Trying to connect a LG V909 3D tablet , works while plugged in but switched off from time to time, how did you connect the black and red wire , is it connected to the 12v straight?</p>
<p>If tablets goes off, I think you have problem with power (watts or amps). You need more powerful power supply or just turn the button. I have 2 buttons/screws on power supply, one for Voltage, and another for W.</p><p>Wires from power supply goes direct to 12V into the fuse box. You can see on pictures.</p>
<p>Hi, thanks for the post. So when there's three pins in the cellphone, the left and right are plus/minus, and middle's probably temperature-sensor. I don't get why the resistor connect to the middle pin?</p>
<p>Our smartphone has thermisistors or resistors that varies resistance upon heat intensity of battery, doing that will give the smartphone idea that it is actual battery not a power supply. Especially a Samsung smartphone i detecting the thermal resistance of batteries.</p>
<p>I also don't know. I just do it, like they do it on the &quot;Discovery channel&quot; :)) I saw on internet and it works:) </p>
<p>Do you have a link to the video?</p>
<p>I have only this video <a href="https://youtu.be/fuLF84dqgxE" style="">https://youtu.be/fuLF84dqgxE</a></p>
<p>That's a nice video, and I like what you have done to it. However I meant the link to the video from the Discovery Channel</p>
<p>:)) This was a joke with D.C. This is part from one old and very popular song ;) </p>
<p>I'm powering my old Samsung GT-S5310L with a cell charger and a diode in between (the chager's open voltage is around 6.2V). The middle terminal is not connected. It works fine.</p>
<p>Great!</p><p>Thank you for your comment!</p>
<p>Thank you for this valuable post.</p>
<p>With pleasure ;)</p>
<p>hi. my idea is to power the phone with 4 AA lithium batteries in parallel and to charge this &quot;battery pack&quot; from the phone charger via phone. will it work?</p>
<p>I don't understand why do you like to use extra batteries? I think, that would be better to use real power bank.</p>
<p>Hi, thank you so much for your post. I tried it in a Samsung J7 but unfortunately it did not work =/. Actually I just need to turn on the smartphone in a external power supply. However when I try it, the smartphone shows a message about low battery and then it turn off. Can you help me?</p>
<p>i think you don't have enough power on power supply. You need more amperes. what power supply do you have?</p>
<p>I have the DC Power Supply DPS-305BM (http://www.amazon.com/DPS-305BM-Digital-Control-Laboratory-Adjustable/dp/B00ON8VPFY) . I set the voltage to 5V (less than that, the smartphone does not turn on).</p><p>Thank you for your answer. </p>
This is too much powerful :)) Set more Volts. Step by step.
<p>I am not sure if you still view this but could I use a 5V rail from a PC power suplie and add some kind of reziseter to it to step it down ? I don't want to over kill my build but it would have a PC in there two so makes sence to use that power ?</p>
<p>Hi</p><p>I don't know. You must to try:)</p><p>From usb on PC won't work.</p>
<p>Great idea, My Aunt should need this!</p>
<p>Great idea, My Aunt should need this!</p>
this is the multimeter i hold to measure. pls assist.
<p>I don't know:)</p><p>Just adjust volts.</p><p>Ampere adjust with test.</p><p>Connect phone to the step down module, turn phone ON and run some &quot;heavy&quot; app, Youtube with HD and put to play half hour. Run browser and open few tabs. Open navigation app... If the phone will not turn off, than is OK:)</p>
<p>And put battery percent on 95-100%. This you will reach with adjusting screw for amperes.</p>
Hi <br><br>Thanks for sharing your effort. I wud like to take some advice from you. Am planng to integrate my phone to car dash like wat u did. From where sud i take the power, so that my phone will switch on and off when i turn the keys.<br>
<p>I think turning phone on&amp;off with car is not good idea. Because duration is too long.</p><p>I dont know how to make that phone will go ON when receive power.</p><p>For shutting down phone when lost power, you can use some tasker app (macrodroid, tasker...)</p><p>For wiring you can use car lighter with car phone charger.</p><p>Or Cable with fuse (Add A Circuit Fuse Tap Piggy-Back) and Lithium Charger Step down, like I did it.</p>
hi,<br><br>today i got the step down module delivered frm amazon. With that i could adjust the volts. my question is how I can measure the amp of my car battery. i tried turning the amp screw clockwise and anti clock wise. cant find any diffrn in multi meter. not sure i chosed correct in multimeter. could you help me to figure out on how to measure with a multimeter..<br><br>thanks <br>rakesh
<p>hi.</p><p>thanks for the idea, I would like to do for my HTC Desire</p><p>I have 4 battery pinout.</p><p>for my battery pin 1 and 4 is v+ and v-</p><p>so may i know how can i do?</p>
<p>Read comments below ;)</p>
<p>but that is different, in between the V+ and V- have 2 pin.</p><p>i found the battery is show symbol &quot;T&quot; and &quot;DQ&quot; </p><p>i think should put resistor on the&quot;DQ&quot; right?</p>
<p>T is maybe for temperature.</p><p>So yes, try on DQ.</p>
<p>Hi, </p><p>Thanks for the idea. I'd like to do the same with an S5 ( SM-G900WB )</p><p>but I have 4 battery terminals and not sure what should be the resistor value..</p><p>Thanks in advance. :)</p>
<p>Hi,</p><p>good question:)</p><p>If you have pins V+, ? , V-, ? I will try to put resistor on the middle one (between V+ &amp; V-).</p><p>http://www.cpkb.org/wiki/Samsung_EB-F1A2GBU_battery_pinout</p>
<p>Yea, the 4th pin is for the NFC... not sure for the 3rd one is for termals.. but..<br>Once I found the battery good pins, how should I mesure the right resistor value ? </p><p>Thanks !</p>
<p>I used 82k&Omega; resistor.</p><p>I saw this on another similar project:)</p>
<p>Hi,</p><p>I got all my wires right, got a great step down power supply(from a 5volts to 3.85) but the phone seams to ignore the resitor 82K... the ''battery'' slowly drains.. have you experienced the same thing ?</p><p>Fresh plug I have about 68%... going down slowly.</p><p>I guess I should try a different resistor value ?</p><p>Any other idea ?</p>
<p>I think your power supply is not enough powerful.</p><p>You need more watts (amperes)</p><p>Paste link of your power supply.</p>
<p>you where right. I was running my DC converter from usb 5v down to 3,85V then 4.0V</p><p>Right when I plugged into a computer 12v source, I got 100% with only two wires didn't plugged the resistor at all.</p><p>it's now on the bench with flashlight and 3hours long youtube video to try to drain it.. I think I'm good now.</p><p>Thanks for the kind help.</p>
<p>of course didn't work ok, USB is only 0.5A or max 1A, but you need 5A;)</p><p>Please paste some pics what did you do;)</p>
<p>Here is the one I've bought.<br><a href="http://www.dfrobot.com/index.php?route=product/product&product_id=752#.VYGqwPnSZ8G" rel="nofollow">http://www.dfrobot.com/index.php?route=product/pro...</a></p><p>I've also increased to 5v flush. now I have like 80% battery..</p><p>if I unplug and replug, I get the 80% back...</p><p>but I'd consuming.. I'm watching 'longest youtube video' with flash light open to drain at maximum and see what happens when it reaches 1% or 0%..<br><br>I'm thinking it might be the 82K resistor .... <br><br>note my battery has 4 leads.. ( with one I believe to be the NFC )<br></p>
<p>hmm...</p><p>power supply looks enough powerful...</p><p>Buy the same one like me. So we will see if the problem in phone, resistor or power supply.</p>
<p>or, you can test with higher voltage. Go step by step to max 1V higher like your battery.</p>
<p>How did you adjust the power supply unit? Which screw does what? Without load it gives out always approx 5 volts, and i somehow hesitate hooking up phone to it without first making sure i have correct voltage.</p><p>Also, what's the resistor value for the extra pin? Any hints on choosing it?</p>
<p>One screw is for Voltage, another is for load regulation (amperes).</p><p>If you always have 5V output, you doing something wrong or is your power supply broken.</p><p>Don't put 5V in your phone. Take a look on battery how many Volts have!</p><p>I have the same problem like you with some very similar power supply (LM2596). I have 3 at home from different seller, and no one works.</p><p>What type of volt meter do you have?</p><p>I used 82k&Omega; resistor.</p>
<p>i love to tinker and have a suby leg. so this instructable is great for me thanx.</p>
<p>just do it ;)</p>

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