Introduction: Build a Power Bank in $2

Picture of Build a Power Bank in $2

Hey! everyone My name is Steve.

Today I'm going to show you How to make a Power Bank in just $2 not believing?

Follow me and you'll get it

Click Here to See The Video

Let's Start

Step 1: Features

Picture of Features

Power Input

  • 5v 2A via a micro USB

Power Output

  • 5v 1A And 5v 2A Dual USB


  • It depends on how much battery you added

Safety Features

  • Short Circuit Protection
  • Over Voltage Protection
  • Over Charge Protection
  • Over Discharge Protection

Step 2: Things You Need

Picture of Things You Need




    Suggested Buy

    • 18650 Battery - Click
    • Vichy VC99 Multimeter - Click

    Step 3: Where to Get Free 18650 Batteries

    Picture of Where to Get Free 18650 Batteries

    I used my old laptop battery to get the cells check the video down below

    Click Here to See The Video

    Step 4: How to Check How Much Capacity Is Left

    Picture of How to Check How Much Capacity Is Left

    I used a Battery Capacity tester to check the real capacity check the video down below

    Click Here to See The Video

    Step 5: Assembling Part 1

    Picture of Assembling Part 1

    • I used 18650 battery holder to hold the 6 battery that I salvaged from an Old laptop battery
    • After that, i used a thick wire to solder all the 18650 in parallel configuration

    Step 6: Assembling Part 2

    Picture of Assembling Part 2
    • I used dual sided tape to stick the battery and the Board to the Acrylic sheet

    Step 7: Completing

    Picture of Completing
    • And then I soldered the 2 wire to the board ( see the image )

    : Notice - Please be careful about the polarity

    Click Here to See The Video

    You Just Made It

    Now just Plug the power and enjoy

    Thank you for visiting my Instructables Stay tuned for next Projects


    pjessing made it! (author)2017-11-08

    I made a simple case for this project and use it all the time. I have included the STL files below.

    ExtosNex made it! (author)2017-09-14

    Well here's my first attempt with this thing

    The batteries I got was from an old portable charger that needed a new USB charging interface. I'm still not sure whether if I should put the batteries in series since the original charger was in parallel. So far it kinda works but from time to time, the thing stops charging and you'll have to press the button again. In the upcoming weeks, I might 3D print a case for this thing to make it look more sleek and robust. I will update this when it somehow breaks from using parallel

    przemek (author)2017-08-31

    The batteries already have tabs welded to them---when you disassemble the packs, just cut the tabs in the middle. This will result in tabs hanging off with the sufficient length that soldering to them will not heat the battery enough to cause damage.

    On the other hand, soldering directly to battery end-buttons is liable to transfer enough heat to melt the plastic between and around the internal electrodes, which could lead to catastrophic shorts and spectacular failures. Similar damage was causing the Samsung Note battery fires last year.

    Another issue: LiIon batteries are more voltage-sensitive than other batteries.. They should not be paralleled---especially if cells have different histories. I haven't seen many commercial packs that have more than 2 cells in parallel, and they use fresh/new cells. The safe way is to put cells in series, and have individual balancing connections going between stages. It's trickier and more expensive but most chargers support that.

    MisterQED (author)przemek2017-09-07

    You are correct on the soldering, but you are reversed on the parallel vs. series idea. The key with Li-Ion is to not let them get out of their voltage range which is 3.0 to 4.2V on the outside. They will last longer if you avoid those extremes. Running in parallel guarantees that all the batteries charge and discharge evenly as they are forced to balance one another. Running in 2S, this means 6-8.4V, but it allows the extreme possibility at full discharge 6V for one to still be at say 4V and the other to drop to 2V or anything else that adds to 6V. Obviously the more cells in series the more possibility for imbalance.

    przemek (author)MisterQED2017-09-07

    You're right that one can't let the Lithium batteries get out of the narrow voltage range---that's why Li charger systems are tricky and can't just be a 'diode and lightbulb' circuit from the lead-acid era. The Li chargers measure individual battery voltage by having individual 'balancing' connections to each level of the serial stack.
    The problem with the parallel setup is this: the Li cells have small internal resistance and narrow voltage tolerance. Small cell differences result in huge balancing currents. Healthy cells that don't differ much will, as you say, just balance out their charged state, but if a cell goes out of spec, at best you just waste the charge out of the good cell, and at worst you can burn up the bad cell with the excessive current flowing from the good ones. Yes you can mitigate that by having balancing resistors and/or fuses on each battery, but why bother f you can just throw a series stack balancing charger on the problem? In either case, you need some sort of monitoring circuit because as you say, you can't let the Li battery charge/discharge out of its design voltage window.
    Simply saying, the Li battery chemistry is much less forgiving than the lead acid, so you need fancy charger, and series stack is just easier to handle.

    MisterQED (author)przemek2017-09-07

    I know about the Li charging as I just got delivery of my new SkyRC Imax B6, :-) and I was with you on charging but Jehu Garcia disagrees. He stated clearly that you can basically trickle charge Li-IOn batteries, as the current will drop to zero as the voltage matches the charging voltage and he has been doing it on his van for two years. I am not saying it is ideal, but it works. It is also probably crazy slow. I also agree that if one of the batteries is REALLY bad then a parallel setup can go south, but I will stand by my original claim, and double down due to the slow charging speed of the battery pack here, the parallel layout is generally safer. Even if we look at real lemon cells, they are much more likely to go south in series then parallel as balancing circuits are not foolproof and can only handle minimal charging differentials between cells. If those limits are exceeded then the balancing circuits will fail and you may not even know that they have failed. This I got from one of the electric bike channels who came out as anti-BMS and pro active monitoring. In the end I think we can both agree the key thing is filter out the real lemons as they will get you in any configuration.

    SexyWood (author)2017-08-26

    Ok, I usually don't comment on many things, but the hat full of A-holes complaining, kill me. $2 is very feasible IF all you need to buy is a board. I have everything listed but the board and it would cost me $2.01 as of today's date.

    And for the people talking garbage about soldering batteries, have YOU ever witnessed such an explosion or fire with your own eyes? I have not seen Lithium Ion batteries do anything but just die.

    I am an electrician with nearly 20 years of industrial, commercial, residential experience. I have been there and done that with "low voltage" and "mains voltage". Simply put anything on the customer side of the power companies transformers. I have been in live switch gears working when they could not be turned off. The reason I list my experience is this, when you're at the level of game in the I.B.E.W. you take classes. More than I care to think about. Some deal with nothing but different kinds of terminations. It all boils down to installing components as the manufacturer says to.

    I admit I have not read any li-ion manufacturers literature that says that their cells cannot have a hard connection to them via a solder joint/connection.

    If you think about it, why would manufacturers weld tabs instead of soldering wire to them? It is all about speed and economy. I am also going to add, I have rebuilt several battery power tool packs with new lithium cells and have yet to have anything go wrong with any of them.

    And why do people want to criticize others so badly? It was not long ago in the US that everything was built to last or be repaired and continue to provide service/use. Now days everything is made to be disposable. Some folks in these "3rd world countries" have less than others and make due with what they have available. Look at Cuba. For decades they could not get parts for vehicles or most anything for that matter, and the level of ingenuity those folks have is astounding and inspiring.

    MisterQED (author)SexyWood2017-09-07

    The welding is also about not transferring heat into the cell. You are correct that a good solderer will "probably" not impart enough heat to damage a cell, but a rookie might. From what I have seen, lots of people solder their cells and they are fine, but the key is to cut down on the heat transfer. Sorry that people are crazy. I've just accepted that fact and move on. Good Instructable.

    alfredmoses (author)SexyWood2017-08-29

    Your post make lot of sense, hats off for your experience.

    Captain_Nemo (author)2017-08-25

    Actual cost is $41.96, not the $2 advertised.

    Connecting batteries of different capacities in parallel is just begging for them to catch on fire.

    lciotti (author)2017-08-22

    Too many things wrong with the to even start to make a usefull commment!

    kbear99 (author)lciotti2017-08-22

    Would appreciate a 'useful comment' on key areas that you think are wrong.

    lciotti (author)kbear992017-08-22

    Your soldering batteries, that is bad I don't care how many times you have done it before. Batteries should have tabs spot welded on. You say it cost $2 to make when all the parts on your list add up to well more than that. Your video shows you testing a battery to so how many amp-hours are left, but you do not account for the voltage drop, you basically test it until the battery is flat. Why do all this when you can go to the store and buy something smaller, well packaged and SAFE for $20.

    I am all for DIY, but make something work your time.

    pintail120 (author)lciotti2017-08-23

    Soldering directly onto batteries is not that bad, put the batteries in the fridge for 2 hours before soldering and that sorts that issue. I have not seen a battery fail or irreversible damage, please demonstrate this to me ?

    Your grammar / spelling is lacking "battery to so how many" - what is that?

    What voltage drop are you questioning, I am an electronic engineer by trade and cannot work out what you are questioning ?

    I think your critique / demeanor is awful and shows poor form, I think you should google how to critique someone and learn a thing or two. Here is a tip on how you do it: first say something NICE, then critique, then say something nice again.

    I think the instructable is not perfect but this is a great learning curve for someone and a great base to improve from. I have both, the store version(which failed and is not repairable), I also have my own home made version which should it fail at any point I can diagnose.

    lciotti (author)pintail1202017-08-23

    Sorry, Did not proof read.

    Should have read "Your video shows you testing a battery to show how many amp-hours are left, but you do not account for the voltage drop, you basically test it until the battery is flat."

    What I mean is he puts the battery into that aH "meter" and he lets it sit until there are 0 volts left in the battery. If you are using this to charge devices, unless that little charger board has a boost regulator on it, when the battery voltage drops below a certain point you cannot charge anything. I can't say if this is true or not because the board has no clear manual available on-line, or at least the one site I went used to check the price did not have one. Additionally, you never should deeply discharge batteries, it is the worst thing for them.

    Sorry, but pointing out errors is not a bad thing. Instructions like this that do not take into regard safety (i.e. soldering to Li-Ion batteries) are nothing but asking for trouble.

    sreeci (author)lciotti2017-08-24

    LCIOTTI, don't waste time with these people.

    Let the battery explode and cause property damage.

    But,do not correct them, they'll not understand, it's the vain EGO.

    sreeci (author)pintail1202017-08-24

    Aw.. come on guy, be reasonable. ICIOTTI, is absolutely correct.

    And no one stores Li-ion batteries along with food storage. That is DUMB.

    A spot welder is EXPEMSIVE, and many in Asia cannot afford that kinda funds.

    Where are you from, anyway?

    Now , don't get mad at me, alright?

    If you retort , it only means, you know nothing.

    Take care. Bye.

    mavellino (author)pintail1202017-08-24

    Applauses from the Balcony

    bryan3141 (author)lciotti2017-08-22

    see? Whether we agree or disagree, this was a useful critique. That wasn't so hard.

    yrralguthrie (author)lciotti2017-08-22

    Oh...I've used the procedure many times and know others who have also. No flaming batteries!

    CybrgnX (author)yrralguthrie2017-08-22

    Soldering is very OK IF!!! the solderer is using the right high power iron so that the speed of solder is fast enough to keep the heating effect very low. Low watt irons and long dwell times are what is the problem. But in general you are correct, as there are too many "tech" who don't really have good solder techniques so they should not be doing it.

    pintail120 (author)CybrgnX2017-08-23

    put the batteries in the freezer for two hours before soldering.....

    CybrgnX (author)pintail1202017-08-23

    See one can learn something at any age...never thought of that! ThanX

    tomjasz (author)CybrgnX2017-08-23

    ridiculous, it's slow down the process. IF you MUST solder solerto th edge of the negative end, and use solder braid techniques. LOTS of fires have been reported when poor techniques are used. Not one single maker of battery packs in the world solders packs. But suddenly we're experts and are certain soldering is not a problem. Right.

    yrralguthrie (author)tomjasz2017-08-23

    In your zeal to make fun of someone, you've failed to understand why battery pack manufacturers don't solder the batteries together. The special crimp they do use is a mechanical hold, which to begin with is better than just solder. Crimping is cheaper. Crimping is much faster. Maybe a factor of 10. I can solder wires to 18650's and then pick the battery up to blow on the joint. Can't get hot enough to harm the battery. We are not talking about the manufacturing process. We are talking about a way to recycle batteries safely into a useful product. And if you want to know, from the number and success I've had with making 18650 battery packs I'm pretty much an expert. Certainly much more knowledgeable than the 18650 police.

    All you experts on soldering technique are latter day prophets. My guru back in the tube days would have had a stroke because no one these days uses a mechanical, twisting the wires, joint before soldering.

    Nothing wrong with this project or technique other than it's been done and reported dozens of times already.

    Koopgids (author)2017-08-24

    Cool project. I like the display that shows the exact charge: most power banks you can buy don't show this.

    Personally, I'd house the entire thing in a 3D printed frame though.

    AnthonyW36 (author)2017-08-23

    Can I just add, if you don't want to solder the batteries, Just buy those battery holders on ebay with leads. They come in 1,2,3,4 cells. All you have to do is is join two 3 battery ones together. If the wire a gauge is to small, just replace with your own higher gauge. Plus it means you can easily replace the batteries when they fail.

    Here is a link to a typical seller from ebay:

    chingada (author)2017-08-23

    nice , cool project but buying all parts plus labor cost y more than buy one already made with solar charging an more efficient space saving lipo battery, and rear flash light.

    Mukund parelkar (author)2017-08-22

    you have to be careful while soldering. heat can damage these batteries. In one of our products we were using these rechargeable batteries but at least 1% were damaged. we used to solder in the tune of 40k numbers.

    put the batteries in the freezer for two hours before soldering.....

    job done

    If you actually damaged 1% of your batteries by soldering you need to consider changing your soldering technique.

    tomjasz (author)Mukund parelkar2017-08-22

    Soldring is NOT a good idea. Better to use a kit like VRUZEND to hold batteries. OR invest $100 in a Arduino nickel strip welder. If you must solder be QUICK. Damaging a cell can mean another fire.

    tomjasz (author)tomjasz2017-08-22

    Solder wick can be the fastest way to attach power leads. Lithium batteries HATE heat!

    ggriffith1 (author)2017-08-22

    I have made a few similar to these, no problems. At the moment I have 60 odd old 18650 cells from laptops and test them with that discharger to establish their capacity down to 3volts. The only problem I see with this project is that it would take ages to charge all those cells with only 1 amp input.

    Also how many of you people who say soldering is dangerous have actually had a cell explode of catch fire? Or are you just repeating stories? I have soldered hundreds of them with my trusty old Scope iron with no problems. Just do it hot and fast.

    My current project is three banks of 5 cells to give 10 AH at 12.6 volts fully charged to use as a jump starter for bikes and cars. My previous one had three banks of 3 cells for 6AH.

    pintail120 (author)ggriffith12017-08-23

    exactly, totally agree with what you say RE soldering these batteries, put them in the freezer for two hours, do it quick and fast. I have done it heaps and the batteries tested fine months later.....

    ivak245 (author)ggriffith12017-08-22

    I think the exploding battery syndrome comes from shorting the positive terminal to the outer case with the iron tip. The negative (case) comes right up and very close to the positive pin, so it is easily done, especially if you have a low-wattage (less than 50w) iron and you are using pressure rather than heat to get the solder to flow. I too have soldered many, using a Scope iron as well (the big one which gets to around 100w in a few seconds, so you do all your work quickly). I touch the terminals to my bench grinder (or Dremel with a stone mounted )so you have a nice clean spot to solder to.

    alfredmoses (author)2017-08-16

    Hi Steve,

    Could you please tell, how is the experience of you buying either from Banggood and Aliexpress, how about taxes and others? Iam from Bangalore.

    hi I'm from jharkhand and I use AliExpress and Banggood Regularly no issues with that

    I use all the time (probably 30 items so far) no problem and they accept PayPal.

    I never used AliExpress for that reason alone (AliExpress does not accept PayPal).

    paulle (author)alfredmoses2017-08-22

    I bought a lot from AliExpress. Shipping is taking little long and unpredictable, so don't buy things that you need right away or certain date. Other than that everything is fine

    TexomaEV (author)2017-08-22

    I buy these kits for very little money, and use salvaged 18650's from laptop batteries:

    TexomaEV (author)TexomaEV2017-08-22

    And these, if I want solar charging, and emergency lighting along with the USB power ports:

    yrralguthrie (author)2017-08-22

    I've made numerous battery packs from old laptop batteries. Some I've solder to several times. I use a little extra flux as well as scruff the end of the battery. Never had one fail. Heat can damage any battery, even lead acid, but it would take an obvious effort to get an 18650 hot enough to fail by soldering to it. I can pick the battery up with my hands immediately after I solder to it! I think the batteries sometimes fail and then they get hot. Not the other way around with a soldering iron.

    AlfieE2 (author)2017-08-22

    The advantage to reclaiming the cells from a laptop battery is that they have tabs spot-welded on. By carefully dismantling the battery, these tabs make it easy to the connecting solder wires. There are often very cheap, new batteries available on sites like Ebay for obsolete laptops. Soldering directly to Li-Ion cells can cause them to explode. Doing so is ill advised unless you want to earn a new nickname like Patch or Stumpy.

    Rufus Akerele (author)2017-08-14

    I would have instructables be in downloaded formats which can be followed up after switching off the handset. Rufus Akerele

    Yonatan24 (author)Rufus Akerele2017-08-22

    Do yoiu want to download this Instructable to your computer? You need to be a Premium Member to do that :)

    ChristopherS220 (author)2017-08-22

    I don't get it and you're going to have to help me out here. You say it's in two dollars yet the first component link I clicked on thru Amazon was $4.99 plus $2.49 shipping.

    tomjasz (author)ChristopherS2202017-08-22

    sometimes you have to look beyond the first link you see. The primary parts is $2.00 on Aliexpress.

    tomjasz (author)2017-08-22

    I buy regularly from Aliexpress and Banggood. Both are slow, but buyer beware, many China sellers are now on Amazon and are just as slow. Pay attention to the listings and shipping time. Often you can pay an additional small fees for shipping on Banggood and get somewhat faster service. ALWAYS look over the boards carefully for cold solder joints and any other problems. These batteries are capable of high averages. 10A output is sufficient to produce tremendous heat and fire.

    Wingloader (author)2017-08-22

    just ordered my parts!

    About This Instructable




    Bio: Hi my name is Steve and i'm a Creative and I got Technical skills i can build anything just stick to my account . I ... More »
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