Build a Power Bank in $2




Introduction: Build a Power Bank in $2

About: 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'm a YouTuber so you also can see my all videos here

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

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




    Suggested Buy

    • 18650 Battery - Click
    • Vichy VC99 Multimeter - Click

    Step 3: 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

    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

    • 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

    • I used dual sided tape to stick the battery and the Board to the Acrylic sheet

    Step 7: 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

    2 People Made This Project!


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    51 Discussions

    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.

    3 replies

    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.

    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.

    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.

    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.

    2 replies

    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.

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

    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.

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

    11 replies

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

    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.

    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.

    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.

    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.

    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.

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

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

    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.

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