Hi, I wanted to see if I could make my smartphone charge on a separate power supply. I took the micro usb end of the cable and soldered the 5v red wire to the board as well as the ground wire. When I connected it to the phone there was no charging symbol, so I used my multimeter to measure a current and there was none apparently. Nothing showed up on the multimeter which led me to believe that the phone was not registering the power supply. Could this be because of the green and white data cables not being soldered to the board?

Thank you in advance! I'm new to circuitry and I wanted to do something unique with a micro USB and this is what I came up with. Thanks again!

 

I think you picked the wrong project for a beginner.
Things that use lithium batteries are intentionally designed to stop amateurs because lithium batteries catch on fire if you treat them wrong.

I don't know how to make a smart phone allow you to risk burning it up, but that's probably a good thing.

 

Aside from me not being able to make the battery explode, the voltage is low on the power supply. I e-mailed the company to check for me to be exact, but the board is 10cm long and that is what generates the electricity. I believe the voltage may even be below 5v. If the voltage is below the voltage of the wire would it not work? I figured if the voltage was low no harm would be done, but too high and it would short. Am I right?

 

If the voltage of the battery? is below the voltage of the wire from a 5 volt source, most batteries will be getting some charging. If the battery voltage gets too high, the battery might overheat, or short, or become an open circuit. Charging a battery isn't as simple as having more or less voltage. It depends on how much more or less. A little bit more voltage does nothing. A little bit more charges the battery. A bit more than that and the battery overheats. A lot more, and the battery gets destroyed.

 

When I connected it to the phone there was no charging symbol, so I used my multimeter to measure a current and there was none apparently. Nothing showed up on the multimeter which led me to believe that the phone was not registering the power supply.

How do you measure current with your multimeter?

You probably blew the over-current protection fuse in the multimeter?

 

How do you measure current with your multimeter?

You probably blew the over-current protection fuse in the multimeter?

I held the ends onto the exposed metal of the diodes on the board. There are 2 dual diodes and one leads to two through holes. On the opposite side of the board there are 4 little silver-like rectangles and the 2 through-holes go through the ones on the far right and left sides. I soldered the wires onto those rectangles as I didn't see any place for solder to be placed on the side with the diodes (there wasn't a copper ring around the holes). The multimeter didn't register anything, so I assumed the phone just wasn't recognizing the board.

 

If the voltage of the battery? is below the voltage of the wire from a 5 volt source, most batteries will be getting some charging.

So shouldn't the wire control the voltage? If I had a 12v source and soldered a 5v usb wire to it and plugged the usb into a battery that could handle 15v, would the battery receive 5v or would the source have too much voltage for the wire?

 

How does a 5V USB cable get 5V?

 

I'm not sure, I was just asking even though I have no clue, to be honest. Can the wire carry any amount of voltage?

Or are you asking me what is giving it that voltage?

 

A wire is a piece of wire. It doesn't have a voltage on its own.

 

Double post, sorry

 

But what if the wire is 5v and the source is 10v DC, would the wire carry 5v and work fine or would it short because of too much power?

I was using a nexus 7 as a test phone, and the cable to charge it is also a 5v DC micro USB. So the wire is fine and it should work with the phone. Do the data pins on the USB alter the amount of voltage and what device it's coming from (like a computer or outlet, etc.)? Because then wouldn't just having the data wires soldered fix this problem?

 

A wire does not have a voltage, so saying you have a 5 volt wire is non-sensical.
A wire will carry current from a voltage source (e.g., a battery) to a load. If you connect a 10 volt source to a load which requires 5 volts, you are risking letting the magic smoke out. In your case, you could let fire out of the battery.

However, the phone likely has protection circuitry built-in, as well as checking that a proper charger is connected. Hence, you are seeing no current.

 

@Geronumo - I am not sure I understand you.
A wire is simple a conductor. The USB wire itself is not 5V.
5V comes from the source which is usually the PC or whatever system the USB cable is plugged into.

 

However, the phone likely has protection circuitry built-in, as well as checking that a proper charger is connected. Hence, you are seeing no current.

That makes sense, but that wouldn't be because of the data pins not sending a signal to the phone, correct? I read that they enumerate and when there is no response from the USB slave device no connection is established and it times out, even if it's not disconnected.

 

That makes sense, but that wouldn't be because of the data pins not sending a signal to the phone, correct? I read that they enumerate and when there is no response from the USB slave device no connection is established and it times out, even if it's not disconnected.

It depends in the phone. You'd have to research what your particular phone requires to charge. There are circuits available on the Internet for making a phone charger for specific phones. I just can't search right now and besides you know better what you have.

 

@Geronumo - I am not sure I understand you.
A wire is simple a conductor. The USB wire itself is not 5V.
5V comes for the source which is usually the PC or whatever system the USB cable is plugged into.

I understand now, the wire is just the conductor. What controls how much voltage is conducted by the wire, if say the source were 10v? The data pins?

 

A USB cable has four wires. Two wires are used for transmitting data, D+ and D-.
The other two wires are used for relaying power, +5V and GND.

The USB cable is just four passive wires. There are no electronics in the cable.

If you connect 10V to the cable, you get 10V out.

Because USB is designed for 5V systems, if you apply 10V to your device you will kill the device.

 

Okay, I think I get it now.

Thank you for answering all my questions