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**Building a Hand-Cranked Power Bank Emergency Charger**

We're getting three sine wave voltages that are 120 degrees out of phase and come with a max voltage of around 5 to 7V. To turn this AC voltage into a DC voltage, we need such a Schottky bridge circuit which I quickly soldered up with 6 1N5817 schottky diodes which come with a very low voltage drop so we don't waste much power here.

After hooking them up to the motor wires, you can see that we are getting a rather bumpy DC voltage on the output with peaks of around 10 to 11V. To smooth those bumps out, you usually add an electrolytic capacitor to the output but since I want an extra big buffer for this quickly changing generator system, I instead went with supercapacitors.

Sadly, they do not wear a superhero cape but those 5F ones for example can store 58 times more energy than this capacitor which comes with a similar size. But their max voltage is rather low so I had to add 5 of them in series to make them compatible with the created output voltage. And as we crank, the capacitors slowly charge up to usable voltage values which do vary quite a bit and are not the 5V we require for the power bank.

So how can we efficiently convert our variable input voltage into a constant 5V output voltage? The answer is of course a buck boost converter that you can get from the internet for cheap. I actually tried using this exact same buck boost converter in my first video about building a hand cranked generator but failed miserably utilizing it because after setting its output voltage to 5V, it works perfectly with voltages between 4 and 15V but as soon as we get down to 3.3V and below, the output voltage quickly shoots up to probably power bank destroying voltage levels.

Back then I had no good idea how to avoid this below 4V input voltage problem but today I am way smarter due to YouTube's educational content they constantly fail to promote and by that I mean I watched my own video about Fuse ICs. By adding a couple of complementary components around this little guy, it hinders voltages under 4V and above 13.8V from passing through and it limits the current to around 1.5A.

I of course tested this eFuse IC circuit with my lab bench power supply before I permanently soldered it to a perfboard onto which I also added the Schottky bridge circuit, the supercapacitors and the buck boost converter according to this schematic which you can find in the video description if you are interested.

Afterwards, it was time to chop up a microUSB cable and solder its red wire to the plus output and its black wire to the minus output of the converter. And finally, I hooked up the motor to the system and thus was basically done building my power bank emergency charger; but does it work?

To find that out, I got my professional test setup here which is basically just my energy multimeter which will measure how much voltage and current flows into the power bank. So as you can see the power bank is hooked up and now let's go for a little test ride and hopefully as soon as we start cranking... yes... yes... it works... Ohhhh it goes down.

There are times when it works perfectly fine, when we can pump in 2.5 to 2.7W like right now and you can actually feel that when cranking. But then there are times when it drops down to something like half a watt, something like that. Not sure if the regulator of the power bank is right now the problem. Hmmmm let's try a different power bank. Luckily I got enough power banks to play around with.

So let's see how this one may work. Ahh no it is going down again. This one does better? 2.3W, not dropping down, constant power, awesome. This is exactly what I had in mind. We are pumping in around 2W of power into the power bank which can be very useful for emergency situations.

So I think this project turned out pretty great. It is awesome that you can take a part from an obsolete product and turn it into something quite useful. And I hope you think so too and if you enjoyed this video and want me to produce more wacky projects like this then consider supporting me through Patreon. As always don't forget to like, share, subscribe and hit the notification bell. Stay creative and I will see you next time. And I will continue cranking, it is soooomuch fun ;-)

WEBVTTKind: captionsLanguage: enNow this a hub motor from a hoverboard.You might be asking yourself what is a hoverboardand I could tell you that they are kind oflike escooters but way worse because theyare only slightly faster than simply walking.That is also why you can nowadays get themsuper cheap secondhand or as we would sayit in Saxony: Die kriegste für en Appel undn Ei.Now I decided to only get a hoverboard motorbecause its electrical properties are quitefascinating.I mean look, I am using 10V DC in order torotate the motor this fast which admittedlyis actually pretty slow.It is so slow that I can easily reach sucha rotation speed by using my hands and thatis the point where it gets super interesting.If I can use 10V to turn the motor slow, shouldn'tit be possible to turn the motor slow by myselfand therefore getting 10V on the output.To test this I added a 1W LED between twowires of the motor and as you can see it isreally bright and I have no problem generatingsufficient energy to light it up.So what are the limits of this setup, howmuch energy can I truly produce and shouldyou maybe have something like this in yourbackpack for emergency situations?Let's find out right after the Intro.This video is sponsored by Skillshare whichis an online learning community for creativesthat offers thousands of inspiring classes.Topics include illustration, design, photography,video, freelancing and much more like forexample electronics. So If you want to learnabout the motor type that is featured in thisvideo then I would recommend you the UltimateElectrical Machines for Electrical Engineeringclass by Ahmed Mahdy that I am watching atthe moment. It surely is a nice a refresher.Currently Skillshare is running a specialoffer; so the first 1000 subscribers to clickthe link in the description will get a 1 monthfree trial. Happy learning!Now first off it is quite obvious that turningthe big rubber wheel is not the best solutionsince you cannot do that continuously.Instead we have to turn the part in the middlewith later something like a crank.And yes, I already altered this part a bitso that a crank would easily fit.But anyway the main problem right now is thatthe wires are rotating along with our axiswhich would turn all of our hooked up loadsinto break dancers and that is something youalways want to avoid.Now my initial idea was to open up the motorand simply reroute the motor wires but atthis point I thought this was too complicatedand thus I continued with a really stupididea instead which you will see in a minute.Before that though let me present you themagical component which more or less solvesour big problem, a slip ring.Simplified speaking it is kind of like a bearingwith wires on both sides which according totheir color scheme are permanently connectedto one another even when the bearing spins.This way by soldering the motor wires to oneside of the slip ring, we get our generatedpower on the other side without having spinningwires anymore, brilliant.Next I took the dimensions of the motor shaftin order to create this crank in Fusion360which I then 3D printed with PETG filament.And after assembling it, it fit perfectlyfine onto shaft.And here is where it gets stupid because Ialso designed and 3D printed an adapter forthe slip ring which I can wear around my armand thus use myself as the fixation pointwhere the wire spinning occurs.And I know it is hard to spot but can yousee the problem with this setup? yep the problemis me and my stupid ideas.So I scrapped this plan altogether, reopenedthe motor, basically desoldered and rippedout all of the wires except the main threemotor wires, drilled a 5mm hole into the centerof the motor rotor and drilled a second 5mmhole through the stator right to where thewires are positioned.Then I used a trick with silvered copper wirein order to pull the motor wires out of thisnewly created hole, guided them all throughthe hole of the rotor and put the motor backtogether.And just like that we got the motor wireson the other side which this time will notbe in the way when I use the hand crank.So as a first proper test I once again hookedup the 1W LED which was way easier to blowup than I thought.Now of course we could solder the motor wiresto a variety of electronics parts and destroythem but we are not caveman anymore.Instead I would love to store the producedenergy in such a powerbank which I hope allmy viewers are familiar with.This way this motor/powerbank combo wouldbe great for emergency situations in whichyou for example need to charge up your phone.So time to get scientific and connect themotor wires to my oscilloscope whose GND referenceis a virtual star point I created with 10kΩresistors.While spinning the motor at a realistic speedwe are getting three sine wave voltages whichare 120 degrees out of phase and come witha max voltage of around 5 to 7V.To turn this AC voltage into a DC voltagewe firstly need such a Sechpulsbrückenschaltungwhich I quickly soldered up with 6 1N5817schottky diodes which come with a very lowvoltage drop so we don't waste much powerhere.After hooking them up to the motor wires youcan see that we are getting a rather bumpyDC voltage on the output with peaks of around10 to 11V.To smooth those bumps out you usually addan electrolytic capacitor to the output butsince I want an extra big buffer for thisquickly changing generator system, I insteadwent with supercapacitors.Sadly they do not wear a superhero cape butthose 5F ones for example can store 58 timesmore energy than this capacitor which comeswith a similar size.But their max voltage is rather low so I hadto add 5 of them in series to make them compatiblewith the created output voltage.And as we crank; the capacitors slowly chargeup to usable voltage values which do varyquite a bit and are not the 5V we requirefor the powerbank.So how we can efficiently convert our variableinput voltage into a a constant 5V outputvoltage?The answer is of course a buck boost converterthat you can get from the internet for cheap.I actually tried using this exact same buckboost converter in my first video about buildinga hand cranked generator but failed miserablyutilizing it because after setting its outputvoltage to 5V, it works perfectly with voltagesbetween 4 and 15V but as soon as we get downto 3.3V and below, the output voltage quicklyshoots up to probably powerbank destroyingvoltage levels.Back then I had no good idea how to avertthis below 4V input voltage problem but todayI am way smarter due to Youtubes educationalcontent they constantly fail to promote andby that I mean I watched my own video abouteFuse ICs.By adding a couple of complementary componentsaround this little guy, it hinders voltagesunder 4V and above 13.8V from passing throughand it limits the current to around 1.5A.I of course tested this eFuse IC circuit withmy lab bench power supply before I permanentlysoldered it to a perfboard onto which I alsoadded the Sechpulsbrückenschaltung, the supercapacitorsand the buck boost converter according tothis schematic which you can find in the videodescription if you are interested.Afterwards it was time to chop up a microUSB cable and solder its red wire to the plusoutput and its black wire to the minus outputof the converter.And finally I hooked up the motor to the systemand thus was basically done building my powerbankemergency charger; but does it work?To find that out I got my professional testsetup here which is basically just my energymultimeter which will measure how much voltageand current flows into the powerbank.So as you can see the powerbank is hookedup and now let's go for a little test rideand hopefully as soon as we start cranking....yes.....yes....itworks......Ohhhh it goes down.There are time when it works perfectly finewhen we can pump in 2.5 2.7W like right nowand you can actually feel that when cranking.But then there are times when it drops downto something like half a watt, something likethat.Not sure if the regulator of the powerbankis right now the problem.Hmmmm let's try a different powerbank.Luckily I got enough power banks to play aroundwith.So let's see how this one may work.Ahh no it is going down again.This one does better?2.3W 1W ahhhh 4WLet's try the last one, probably the simplestone.2W, not dropping down, constant power, awesome.This is exactly what I had in mind.We are pumping in around 2W of power intothe powerbank which can be very useful foremergency situations.So I think this project turned out prettygreat.It is awesome that you can take a part froman obsolete product and turn it into somethingquite useful.And I hope you think so too and if you enjoyedthis video and want me to produce more wackyprojects like this then consider supportingme through Patreon.As always don't forget to like, share, subscribeand hit the notification bell.Stay creative and I will see you next time.And I will continue cranking, it is soooomuch fun ;-)