Creating a Cell Phone Charger from Batteries: Understanding the Process

[Regenrok]

Hi, I'm currently working on a project: I'm trying to make a cell phone charger from an Altoids tin and batteries. I know there are countless tutorials out there, but I want to understand why everything happens and how it works. I'm getting to each problem individually, so that I can find a solution for that specific problem and understand what's going on. I have two 9V batteries I want to connect to a female USB end, then connect a USB charging cable from the phone to the batteries. I'm using an old phone, so I don't mind accidentally screwing it up, I'm just worried about getting the power to the phone initially; and then I'm worried about getting the correct voltage and amps to the phone.

Thus far, a single 9V battery connected to the phone via the USB circuit does not cause the phone to respond. Why is this?

Also, would any other battery combination be more efficient, and for what reason?

Thanks in advance for any attempted assistance.

 

[Jason49]

The phone does not respond to the 9v battery because the voltage is to small for the sensors to pickup

 

[davenn]

The phone does not respond to the 9v battery because the voltage is to small for the sensors to pickup

I don't think so, considering all the cellphone chargers that I am aware of supply 5V

9V is too high

Regenrok. try again with a battery pack that will supply 5V Plus or minus 0.5V

and did you use the correct wires in the USB cable ?
The outer 2 wires are the 5V supply wires, the inner 2 are the data wires

Dave

 

[AlephZero]

Try again with a battery pack that will supply 5V Plus or minus 0.5V

Indeed. USB ports always supply 5V.

If you apply 9V (or 18V) directly to the phone, you are hoping there is something in the phone to protect against the over-voltage.

(For completeness, the USB 3.1 specification does include higher voltages and currents, but it also uses a different connector. AFAIK the final version of the spec has not yet been published and so far no USB3.1 devices have been marketed.)

 

[alphy]

I find your project to make a cell phone charger from batteries very interesting. It is great that you want to understand the process and not just follow tutorials blindly. This shows a true scientific mindset.

To answer your first question, a single 9V battery connected to the phone via the USB circuit may not be enough to power the phone because the voltage and current provided by a single 9V battery may not meet the requirements of your phone. Most phones require a voltage of around 5V and a current of at least 1A to charge. A single 9V battery may not be able to provide enough current to charge the phone.

To overcome this issue, you can try connecting multiple 9V batteries in parallel to increase the current output. This will provide a higher current output without changing the voltage. However, you should make sure that the batteries are of the same brand, type, and charge level to ensure safe and efficient charging.

As for your second question, there are other battery combinations that may be more efficient for charging your phone. For example, you can use a series of AA or AAA batteries to provide the necessary voltage and current. These batteries have a lower voltage but can be connected in series to increase the voltage output. Additionally, rechargeable lithium-ion batteries are also a good option as they have higher energy densities and can provide the necessary voltage and current for charging your phone.

It is important to note that when working with batteries, safety should always be a top priority. Make sure to use batteries of the same type, brand, and charge level to prevent any potential hazards. Also, be mindful of the voltage and current requirements of your phone to ensure safe and efficient charging.

I hope this helps in your project and I wish you the best of luck in your endeavors. Keep exploring and learning, that's what science is all about.