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Powerbank for small load

What powerbank keeps supplying current and does not turn off if the load is only a few mA ? All the ones I have tried turn off automatically after a few minutes.

Question by Dpu    |  last reply

Combine 2 powerbanks for mobile

Hello, I have 2 old powerbanks that didn't have enough cappacity. So I want to combine the 2. But both have 5v 800ma output. So if I am afraid that the voltage or the ampere will be to high. How can I combine the 2 without damaging my phone? Sorry for my bad english. Greeting, Thijs

Topic by Thijsd4    |  last reply

Do I need another powerbank?

If I have 2 devices that are rated for a maximum current of 4.5a and a powerbank which puts out a maximum of 4.5a, would both devices run off of the powerbank at the same time or would it need a 9a output for that to work?

Question by ambientvoid    |  last reply

Cheap powerbank shows light but than stops?

Hi, I have bought a cheap power bank, it worked good! But now there's something strange, I know it's cheap so it doesn't work long but if I charge my powerbank it shows a light and than the light stops showing and the powerbank doesn't do anything anymore. I saw somewhere that you can take out the battery inside and plug it in to a battery charger? Does that help?

Question by SimonU2    |  last reply

stepping up 12V powerbanks to 30V DC

I bought some RC Lipo battery packs to power a speaker system but since then i've moved and my new landlords have thrown a fit about me charging them on the premises because of the (small) potential fire risk so one possibility im considering is using a powerbank or 2 instead as they have no problem with those. my problem is that the amplifier requires 30V but most slim powerbanks put out a maximum of 12V so could i either safely step up to 30V from 12V or join 2 powerbanks to step up from 24V?

Question by ambientvoid    |  last reply

Is it possible to repair or repurpose a power bank charger where the mini connector to charge it has become dislodged?

I have an EYON power bank. A year after I got it, the mini connector broke off inside so I could not recharge it. I would like to either repair it or find a way to repurpose it to recharge it and then power/charge things but I don't know enough about how to safely open it without destroying it.

Question by blodefood    |  last reply

4p 18650 power backup using TP4056's with protection

Hi Everybody, I need help with project I am up to so any advices would be much appreciated. Setup: Laptop power supply 20V 3A 4x TP4056 with protection 4x 18650 lion cells of different condition 4x P-MOSFET 4x Schotky diode 4x 1k resistor 1x step down module 1x step up module Task: Want to build 18650 cell charger (backup power supply) using 20V power supply and charging circuit with TP4056 in parallel. Goal: Should be able to run constantly connected to main power supply being able to simultaneously charge the cells (and cut them of while fully charged) and supplying power to the load. For the input I plan to use step down convertor to get 5V (for parallel connected TP4056 chargers) and for output step up convertor to get 12V for the load. I did a lot of research already, therefore I incorporate P-MOSFET, Diode and 1K resistor to not to disturb the precision of the charger and prevent the drain of the cells once charged. I also draw the circuit how I think it should be done. I am new to this so I will appreciate any input, correction or alternative to this. Whole idea is to be able to charge cells which are unmatched without balancer and being safe. I am not sure if the TP4056 protection would serve sufficiently for this. Also am interested how much would be maximal possible current output. Plan to use Samsung IRC18650 24b cells at the moment which I salvaged from my old laptop battery.

Question by pavelkryml    |  last reply

DIY Powerbank, I need to know something first :)

Hi guys! We have this project on making a powerbank of our own. But I don't know how to start, what to use. Here are my questions. Is it possible to make a powerbank without using the 5v usb stepup board?  If that is possible, how?  How will it discharge and charge without that board?  Help please!!!  Thanks in advance.

Topic by iBenzzz    |  last reply

Troubleshooting usb powerbank 3 IR LED setup

I am an amateur with setting up circuits, but I am really interested and understand most electronics, I am just confused with the issue I am having. Background:  I am building a wireless google cardboard so that I can play PC games on my phone through the VR headset rather than crappy app games. Basically a wireless Oculus Rift, however I know it wont be anywhere near as good it's just a fun project. I have Infrared LEDs which I will use with freetrack and my modified webcam without IR filter to do my head tracking. Issue: I am trying to power 3x Infrared LEDs from a usb powerpack. Here is the one I am using;=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 The reason for using this as a power source is I can easily attach it to the headstraps on the google cardboard, it is just about the smallest power setup I can think of (better than using 3x AA batteries), it was cheap, and it outputs 5v which is perfect for powering 3x IR LEDs with a forward voltage of 1.6v and 60mA current. When I use this powerbank to power a single LED without a resistor and I look at it through my webcam, even with all the lights off and the webcam 5mm away from the LED you can barely see it light up. I tried the led on another powerbank I have here which is 10,000mAh so it is massive, and it was much brighter on the webcam. I then used my samsung TV remote and pressed a button while aiming at the webcam and it was EXTREMELY bright. Basically I want the LED to be as bright as my remote, or as much as the LED is capable of. Why would the powerbank show the LED so dull? I have confirmed it is outputting 5v, but when I try test the current with a 'usb charger doctor' between the charger and usb cable, or a multimeter between the wire and the LED it shows zero current. I should be able to just connect all LED in series with a small resistor and it should just work at full brightness, but the power bank cannot even power a single LED well enough to see properly on the webcam. It's becoming really frustrating, any idea what's happening? Best solution?

Topic by dom.curulli    |  last reply

Can I power a raspberry zero + arduino with a powerbank?

Hello everyone, I want to make some kind of driving computer, but I don't know how to fix the power. I have a 16000mah powerbank that has a 1A and a 2A power output with 5v. And I want to power the following: Raspberry Pi zero Internet dongle Arduino Arduino Motor Shield 4 motors(DC 3-6v each) 2 servos 1 webcam (optional) I really hope someone can tell me if this is possible. The reason I don't want to use normal battery's is because I want a solution that is easy to recharge.

Topic by Thijsd4    |  last reply


Hi, I'm building a mini BB-8 unit for a project and going to make many more for a club. My biggest problem I'm encountering now is the battery needed to power it. The entire circuit draws around 500mAh and runs  on 3-5V. I don't think a 9V battery is enough to power it or even a AA battery no matter how many i put on it. The online guides that I found uses 18650 batteries either salvaged or bought. However, from where I come its very expensive to buy this batteries and it the charger cost even more. So I was thinking of buying this cheap 2400mAh powerbank that is sold commonly here. It outputs 5 volts and can be charged by USB. This powerbank cost about the same price of a 9V battery but only have life span of about 2 months which is good enough in my opinion. My main question is are there any other alternatives to power this circuit at a cheap price and is it possible to use a powerbank to power this circuit? Tq for any help and suggestions.

Topic by KhayhenS  

Setting up a Led light strip with 44key IR remote to a powerbank battery pack?

I am wanting to set up a 1M long RGB led light strip with a 44key IR remote with a working input voltage of 12V DC, working power of 36W/5M and 5A/5M, there are 60 LEDs/M. I would like to try to use my Duracell Power bank, that has an input and output of 5V dc and is a 2200mah batter pack. If I need to I can buy another battery pack, it needs to be smaller as its for a longboard for lights underneath, My main question is, Is this possible to set up? and what is the easiest Way to do it? Any help would be great, Thanks.

Question by seth.beliveau.5    |  last reply

Help on a phone automatic charger project

Hello everyone,Im trying to build a circuit that allows a phone to be charged by a PowerBank automatically and I obviously need your help since Im kinda new to all this.So the idea is to connect a phone to a powerbank using a relay. This relay is controlled by a PIC16F877A.The Powerbank turns on once it is connected and off when disconnected. Im planning on using an android application to turn on the flash light once the phone is on 15% so that the LDR detects it and the PIC command the relay to switch. So once the powerbank gets connected it should turn on and start charging the phone. what do you think ? can i use a MOSFET instead of a relay ?my problem is on the determination of the exact components I need so that the phone gets charged correctly.Basically, the powerbank voltage is 5V and the phone draw a current of about 1.4A.What is the best relay and transistor to use ? or should I simply use a MOSFETHere I used a 5V relay but I need to determine the coil current to determines BJT collector current --> this determines useful BJT base current --> this determines useful base resistor values.I hope you guys can help me pick the right components to use and advise me of how I can make this work perfectly.PS : the simulation is working just fine

Question by AbdChahidS    |  last reply

any possible way to make this led ring flash run off of a usb power bank?

I have a  MK FC-110 LED Macro Ring Flash that runs off 4 AA batteries, is there any way to add a usb wire and make it also be able to run off a power bank? please let me know thank you. 

Question by HectorV39    |  last reply

Powerbank has 3 USB outputs 2x2.1A and 1x1A all 3 are 5v, Can I power a small audio amplifier with these connected...?

Hey  Powerbank has 3 USB outputs 2x 2.1A and 1x1A all 3 are 5v, Can I power a small audio amplifier with these connected in series, or would they all need to have the same amount of amps? I currently run the audio amplifier off of 2x9V PP3 batteries, but these run out of charge too quickly and I'm am trying to see if I can run the amplifier off of a 50,000 mAh portable powerbank? I also have another powerbank with 2 USB outputs 1 x 1A and 1 x 2.1A (both at 5 volts) should I just run the amplifier off of the 2 x 2.1A outputs and the 1 x 2.1A output of both powerbanks connected in series, or is it fine to connect all three with the power bank that has the 3 USB outputs (50,000 mAh)? Thanks in advance

Question by MrShauny    |  last reply

Calculate Resistor for Heating Wire

Hi there, My Goal is to use a piece of heating wire from an old hair dryer  (1.6 Ohms resistance for the length i want to use.) and heat it red-orange using my old USB power bank. 5V output from an 3.8V lithium ion battery i dont want to mess with the circuitry inside. Problem: The USB Power Bank has short curcuit prevention built in, so when i connect the heating wire the power bank stops supplying electricity. I found a 7.5 ohms resistor and connected it aswell, the wire became a little warm, the resistor incredibly hot but most importantly the power bank continued to supply power - success. I would like to know what resistor i should use to get the wire red-orange hot but at the same time keep the power bank safe and not overwhelm it - i think that would mean not drawing too much current? I also cant check how much current is flowing because my multimeter is too cheap and only goes up to 200ma, which the power bank exceeds. So how would i go about this? What resistor should i use for what wattage should it be rated. And since im a total newb id like to hear your train of thought as to why and how. Thank you so much.

Topic by emiliori    |  last reply

Combine (relay?) multiple cellphone batteries for one large powerbank

I rarely trade my previous primary mobile devices when upgrading; as a result, my cache of obsolete phones with perfectly useable batteries is a dozen, give or take. I'm sure not many, if any, tinkerers, modders, hobbyists, etc., would recommend such a project, as these batteries can be unforgivably volatile if used any way other than their manufacturer's suggest, and sometimes even then. So let's assume we've all been warned; no need to reply "don't...". that being said, has anyone here ever attempted anything like this, or know, or heard of someone who has? if so, links would be much, i ask because i'm considering trying to mod an old rc car into a wifi/app controlled car, and repurposing as much of my neglected junk as i can to do this, would be soo satisfying.Thanks!

Question by rays-nalley    |  last reply

how to make a power bank to charge your laptop?

I have an idea to make a power bank that can charge my laptop, but I don't know how to make it. The adapter input is 100v-220v~ 1.83A and the output is 19.7v ~3.87A Please, I really want to make it real and I think many people have the same idea, so I need your help.

Question by MirzhaK    |  last reply

Laptop powerbank 12v to 20v and upto 5A output using 18650 batteries with USB 5v added

Hello ladies and gentlemen.  Im looking into buying a laptop powerbank charger for my Lenovo X1 carbon that charges at 20v 4.5A 90w fast charge with upto 80% charge in 1hr. But it will also charge at 65w and maybe 45w I've read. But this will not give me the full power of the processors and gpu etc. Unless I charge at 90w 4.53A  there are are some powerbank that are around £100-170 for sale but these don't give full 4.5A. Mainly around 2-3.5A so will maybe or maybe not charge she give me full power of the laptop   so I'm thinking about making me own using 18650 batteries. Good Samsung or LG 2500maH plus cells. Prob around 3000mah.  Im thinking I could either use a buck down or step up and use the batteries on series from 3S to 8S and then 3-4P to give me around 10000mah. I'm looking for the best efficient output so I'm not sure whether to use higher input or lower input to give me 20v.  Or or maybe I could go the inveter route using a 12-24v 150w inverter?? Efficiency is the main thing here. What is the best option do you think. Should I use 12v or 24v for max effecient conversion.  Ive searched the instructables for such devices but cannot seem to find anything like this. Or would I be better to buy one??? I would want to add USB and USB c also. Defo USB 2.0.  Could you you please help me choose and find the answers please?  I fancy the DIY route because I'm looking into solar and battery power storage and also boost my range wifi range through either ptp or directional attenna. These projects will come after the laptop powerbank.  Any my help would be appreciated a lot.  Kind regards.  Scott. 

Topic by ScottL190    |  last reply

How to get constant 5.2V from ~1-7 Volts?

I have multiple solar panels (3V, 6V). I want to build a charger for bicycle, to keep my battery powered lamps (DIY) battery alive. Currently, I use my DIY lamp with a USB Power bank (5,2V , approx. 50k mAh), but my lamp contains 39 LEDs, and they are ultra-bright LEDs, so they drains the battery fast. So I thought if I connect some solar panels to it, I can charge power bank during daytime.

Question by Sp1k33    |  last reply

Can I wire a relay delay module to be more effecient on standby

I made a timed light powered from a usb powerbank, and a 5v relay delay module (like this ), I powered the module and the light (switched on by the module) in parallel from the powerbank, then ran a momentary switch from trigger to negative. Press the button and it switches on the light for a set interval (about 15 seconds in my case), so far so good. The problem is that the powerbank (cheap and low capacity) runs down after a few days, primerily from the trickle of keeping the relay module ready for use.Is there a simple way to stop the wasted current?

Question by oragamiunicorn    |  last reply

How many led lights can I power with 5v 2000mAh power bank?

I'm a guy who tries everything. Not an engineer or electrician but I would like to make a DIY camera light using LED strip and one or 2 5V powerbanks. Please advice on how to go about it.

Question by ShingaiG    |  last reply

Choosing the right zener diode? Answered

Hi Guys, I want to make a power bank kind of thing that can charge my laptop. Its not at all efficient and a powerbank or rechargable batteries would be better but its a challenge kinda thing. Due to my research I found out that zener diodes can not only prevent backflow but also limit the current. So I was wondering if you guys could help me choose a zener diode. I have attached a picture of the schematics. Please don't comment saying that its not efficient and stuff, I know that. ( Extra info: laptop requires 20 volts 2 amps) Thanks in advance :). -Prickly Potato

Question by The Prickly Potato    |  last reply

How much and how efficiently can a capacitor store charge?

I recently found out all the items required to build this project: .  I don't want to buy the power bank, so I though about using rechargeable batteries. But I had none, but I had capacitors and I thought of using them.  These capacitors 1000 uf . I am thinking about soldering 5 of them in paralell so that I have 5000 uf storage capacity, But I am concerned how well it would work, if at all.   Can this store upto the amount of charge that a powerbank can? Can it actually charge up at a constant voltage if I use it?  Thanks for helping!

Question by aninda13    |  last reply

How to connect an attachable object the best using arduino

Hi all technical people, I have a question regarding my project. For the project we have build an flower containing a neopixel. This neopixel is attached to iron wire. The object is part of an installation in which you can hang the object so it can light up. Besides that the object can be used on in a stand-alone object which is powered by an powerbank. And now the problem. The iron wireing works fine when the object is hung up, but when put into the object it doesn’t connect very well. Is there anyone who has an idea on how to fix this. When the object is placed in the stand-alone object and the on button is pressed it should light up without problems. All of this is done with arduino. The powering and code is not the problem, the connection between the objects is.

Question by KellyV17  

Help needed for a diy bluetooth speaker

Hi,I have 2, 10 Inch JBL speakers from an old music system. I dont have a photo right now, i will post i later. i am not sure if its a woofer or a speaker coz it have 2 magnets below. one over another and inside there is also a small speaker in the box. So i got 2 big speaker(or woofer) and a 4 inch woofer driver from a jvc multimedia system.I am kind of an audiophile and i want help to build a good boomboX with whatever i got. i am familiar with wiring and soldering and that kinda stuff. but i dont have anything to fabricate any circuit boards. So pls suggest me parts with low cost and those which can be bought inside India. I also have a bunch of 3.7 V rechargeable batteries from powerbanks and rc helicopters. But dont have a way to recharge them or use it for a regulated supply

Question by Syst3mburn3r.  

What stepper motor should I buy?

I am new to stepper motors and didn't have one. Just need to make sure that I will buy the correct stepper. My project is about DSLR camera pan + tilt and for slider, so it will be 3 steppers. Maybe can carry 1.5kg - 2kgI already have the following:Battery: Laptop powerbank USB1:5V/2.1A USB2: QC2.0 port 5V/2A 9V/2A 12V/ 2ADriver: Adafruit Motor Shield V2 for ArduinoArduino: DFRduino UNO R3And some 1:40 reduction gears from past projectAbout the stepper I'm planning to order in and here is my choices: 12-24v, 1.8 step, 0.5 amps, 20 resistance, hold, detent 12-24v, 1.8 step, 0.28 amps, 26 resistance, hold, detent 12v , 1.8 step, 0.4 amps, 30 resistance, hold, detent 12v, 1.8 step, 0.4 amps, 30 resistance, 260mN.m hold, 12mN.m detentPlease let me know what should be best for my project. I'm not expert in steppers. If you have any suggestions that would be great.Thank you!

Topic by coreuploader    |  last reply