heavy duty portable charger for usb devices (phones, ipad, etc.)

by:CTECHi     2019-12-29
Do you need to charge your phone during the trip?
Can\'t find a wall outlet to charge your iPod?
Whenever I am not at home for a long time, I charge my phone and mp3 player from my laptop.
This way I can get about 3 to 4 full charges from my laptop battery and I can leave the phone and mp3 player charger at home.
But it seems a bit too much to take a laptop with you to charge your phone and mp3 player.
Later, I discovered the very popular miniature battery --
A power supply device that charges a USB device.
However, after I made it myself, I found that the two AA batteries used in Minty Boost did not have enough juice to feed (
Several mAh AA batteries in 2000 gave me about half of the phone charge before they were sent out).
So I decided to combine the capacity of the laptop battery with the portability of Minty Boost: heavy duty portable charger.
The device is based on DC/DC boost circuit and micro controller (Iused a PIC)
And a small amount of 18650 lithiumion cells.
The laptop battery usually contains 8 of these batteries (
While I noticed that only 3 were used on my netbook, this explains the lack of battery life).
I have harvested the battery of this device from the old Dell laptop battery, but you can buy 18650 batteries cheaply on ebay ,(
You can see one in the upper right corner of the picture below),.
Note: for this instruction manual, you need experience in circuit construction, programming, and use of a micro-controller.
I already have the source code for PIC12F683, but the same circuit works for Atmel or other microprocessor as well.
Note 2: Although I have designed simple circuits from scratch, the general principles behind this circuit have been established and I believe that many people who make this device will reach very similar circuits.
Not intentional infringement.
The picture shows the final device that charges my phone and runs a USB fan at the same time. This device contains 4 18650 batteries and has two USB sockets built into the 8 cm CD wallet, I found this to be a perfect size.
People familiar with Minty Boost or similar devices may point out that the benefit of AA batteries is that they are everywhere, and if you are out of power, you can go out and buy some more;
Unfortunately, this is not the case with 18650 cells.
My argument for using 18650 cells is: first, build and use a Minty Boost-
Type the device for a while and I can say I \'d rather wait until I get back to the hotel than go out and spend money on more batteries (
This will give me half the cost anyway).
Second, lithium
Compared to the NiMH battery, the energy density of the ions is about 3 times, so for batteries of the same weight, you should be able to pass until you reach the power point before it has to be replaced.
So both 18650 and AA have their own advantages. here is a comparison between small lifts.
Type equipment and heavy charger: Minty-
Increase: Battery Type: 2 * AAApproximate energy capacity *: 20 kJPros :-Small-
Heavy duty charger with ready-made AA batteries18650: Battery Type: 4*18650 Li-
About Energy Capacity: 128
More than 6 times the energy capacity
Higher current output * energy capacity calculated using equation: no
Battery * battery voltage * battery Ah capacity * 3600 = energy capacity * I have never tested the maximum current output of the device, there are some problems with heat dissipation at higher output power, the effective output current is limited.
As shown in the figure is the scale difference between the two devices, as well as their batteries.
On the left is a mini Boost I performed myself-type device.
Built in a box to hold my cuffs-
Link and run of 2 AA batteries and an lt1353 DC/DC chip (
The current provided by ibelive is slightly smaller than the MAX756 of Minty Boost).
The core of all these devices is the inconspicuous DC/DC boost circuit, which is essentially the transformer of the DC power supply, which will increase the DC voltage (say 2.
4 V for two AA batteries)
High DC voltage (
USB charging 5 V).
A shortage of Minty boots --
The type device is to use a micro-power DC/DC boost chip.
These ICs encapsulate the transistors, sensors, and oscillators needed for DC/DC circuits into a neat 8-
The pin package of the circuit can be built quickly.
Unfortunately because they are \"micro power\" they are not designed to output higher power, but luckily they usually have enough power to meet 100-
USB needs 200 mA.
To solve this problem, I decided to build the DC/DC boost circuit myself.
Disadvantages of not using pre-
The packaged IC is that I have to set up my own control circuit to control the DC/DC boost circuit.
The good thing is that now I can select components with higher power levels so I can get more output current.
In order for the circuit to display large enough to see the text, I had to split the circuit into two halves and the next few sections would explain the component selection.
The list of components and circuits are as follows, 18650 batteries from left to right (
And battery clips)
: I use 4 18650 batteries in parallel and generally you should avoid doing this because there is some risk of overheating when the battery tries to discharge each other.
If you want to make sure it\'s safe, you can add a diode after each battery so they can play well. These lithium-
The end voltage of the ion battery is 4.
2 v drops to a minimum of 3 v when fully charged.
Any number of cells in parallel can be.
You can also use AA cells, but you may want to stack them in twos to create 2. 4 -3V.
Note: but you decide to set up the battery, do not exceed 5 v, the DC/DC boost circuit can only boost, can not reduce the voltage.
You need a DC/DCBuck circuit instead to reduce the voltage.
For the battery clip, I cut and bent some paper clips. a switch (SW)
: This is the power switch and it is optional because you can keep it on all the time and the circuit won\'t consume much power if it stays on and doesn\'t plug in any power.
Smooth electrolytic capacitor (C1)
: I use the 220 uF capacitor, which is for smoothing, so Minty Boost uses 100 uF in 100 uF.
Reference voltage diode (D2)+ resistor (R1)
: You need something like low power 2.
The 7 v Zener diode provides you with the correct voltage reference for the micro-controller.
If you don\'t have a Zener diode, you can use a normal diode like I do (
If you use a normal diode, you need to connect it to the Zener diode in the chart in another way). I (
And the code provided)
The 1N4001 universal diode and 10 kOhm resistor are actually used.
You can also use the ician LED of the voltage reference (D3)+ resistor (R2)
: Any LED and proper resistors are finea micro-controllers: I used PIC12F683 and these are very small chips for simple circuits as they can run out of 2 v5Van inductor (L)
: The boost circuit needs to do this, the higher the inductance value, the smaller the current ripple.
I used an inductor that I wound myself and it may have an inductor in the mH range and I know it is very large.
This is a useful online calculator that can calculate the inductance.
I recommend using at least 200 uFan pnp transistors and base resistors (R3)
: This is the main switch device in the circuit plus the base resistance (
OR gate resistance)
Make sure your transistor is designed to handle high current (
Preferably above 1A)
At a high switching speed (20kHz or more)
At least 50 hFE.
I have had a success with general purpose BC337, but be careful about overheating.
There is also a mosetworks (
May give you more efficiency).
I am using d12 because I have one lying nearby.
Tear it off a CD drive that already doesn\'t exist)a diode (D1)
: This is what the boost circuit needs, fast
Switching diodes are the best, so I used a Schottky diode (1N5817)
Although a universal diode like 1N4001 can also work on two resistors (R4, R5)
: 5 v output is higher than the power supply voltage (
ADC Reference voltage)
Therefore, this output needs to be reduced by two equivalent resistors (
Iuse 22 kOhm resistor)
A voltage divider will be formed, allowing the 5 v output to be halved.
Another smooth electrolytic capacitor (C2)
: Again, I used a 220 uF capacitor or usb socket: I have used 2 outlets that you still need: some wiresome prototype boards: strip-
Board or breadboard, or anything you want to build a circuit on it.
Battery Charger: you need something to charge your battery!
You can buy the 18650 charger cheaply on some kind of housing in eBaysome: it can keep your circuit in it.
You need something bigger. . .
I used a CD box of 8 cm (
For those 8 cm miniCDs)
Computers and programmers for the micro-controller: Obviously, you need a computer programmer to load the code onto the micro-controller.
Below: A cheap 18650 charger from eBay with about 18650 batteries next to it.
I bought my 18650 with some old laptop batteries, but you can also buy a new one.
There is no obvious difference between the two, except that the old laptop battery may have reduced capacity due to age, unfortunately I didn\'t take a lot of photos during the build, i\'m assuming you have enough experience in circuit construction to be able to read the circuit diagram and build it for yourself.
If not, there are some great guides on building circuits, so explore it!
Below is a picture of the almost finished board.
There are a few things that need to be done with the code that needs to be loaded on the micro controller: 1.
Detect reference voltage: this is done using a voltage reference diode ,(hopefully)
This should produce a fixed voltage regardless of the battery input voltage.
If you use 2.
7 v Zina, the output voltage should be 2. 7V (
If you adjust the size of the resistance according to the data table.
If you are using 1N4001 universal diode and 10 kohm resistor like me, the voltage should be around 0. 5V -0. 525V2.
Set the output voltage: the micro-controller outputs the PWM signal to control the transistor and the DC/DC circuit, and the higher the duty cycle, the higher the boost ratio.
To ensure that the output is 5 v, the micro-controller must adjust this PWM signal to keep the output at the target voltage.
This is done through sensing and feedback;
Output voltage detected (
Through the voltage divider)
, Adjust the PWM signal if the detected voltage is different from the target voltage.
The target voltage is calculated in multiples of the reference voltage.
In my case, use 0. 5V -0.
The reference voltage is 525 V and PIC is trying to keep the induction voltage at 4.
85 times the reference voltage. 3.
Check the battery voltage: this is also done using the reference voltage and if the battery voltage drops below 3 v then the indicator LED flashes. (
Discharge Lithium
Too many ion batteries can cause bad things to happen, I actually recommend adding an extra transistor to disconnect the output if the voltage drops too low)
Attach some C code that will be compiled for PIC using MPLAB and HI-
Pic c compiler for TECH.
Hope it should be its ownexplanatory.
I have used some basic averaging procedures which may not be necessary.
If all goes well, you should have a charger that is functioning properly. Enjoy!
Other information: some devices, especially the iPhone or Motorola phone, need to connect some resistors on the USB data cable (
Not connected in this circuit)
, If your device is not charged.
There is some information on the Minty Boost website about charging the iPhone 3Gs.
Disclaimer: Lithium
The ion battery may explode if not handled properly, please do not try this instructions if you are not familiar with the building circuit or use lithiumion batteries.
The author is not responsible for any harm or damage caused to himself or property by attempting to recreate something in this manual.
The information contained therein is only a guide and should only be followed if necessary knowledge of building circuits and electrical safety is available.
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