A lot of stories, or rather excuses, can be shared about why your cell phone died on you. Most probably, it ran out of juice and its battery went flat. How do you charge a phone battery especially when you have no immediate recourse to your charger plug but desperately need that phone to work?
- A typical cell phone battery will need about 3.5 – 4 volts and a car battery in general is 12 volts.
- Your aim is to reduce the car battery voltage to complement the cell phone’s for which you need a resistor (it reduces the voltage). The material of the resistor should be able to conduct electricity in small quantities, and it does not even need to be metallic.
- Your goal is to transform electrons (electrical energy) from the car battery to your phone battery without one frying the other. Pencils to the rescue!
- The cheaper the pencil the higher the resistance, up to 15 ohms or more. The central lead core is the trickster behind this jig. The longer the pencil, the more the lead, ergo more resistance. Get a standard 6-inch one.
- Your phone battery will have three small ‘golden’ power strips. One is positive, the last one is negative, and a blank one sits in between and deals with temperature control so the battery does not over-heat.
- Sharpen both ends of the pencil. Let the lead tips be blunt; make them so. You are going to connect the positive and negative terminals from the 12 V car battery to either end, veritably transforming the pencil into a voltage divider.
- Shave off a segment of wood somewhere in the middle of the pencil, just until you can see the lead core. Since it is a 6” pencil, the lead exposed exactly at the middle means a voltage of 6 whereas if you expose a portion closer to any one end, you can wield 3 volts.
- You need 4 volts, so [6 x 4 / 12 = 2 inches]. Expose the lead core at the 2-inch mark from any one of the pencil ends.
- You need to cut the wood off the pencil in such a way that enough lead is showing for the wire fixtures to work with while enough wood is present to act as firm support lest the pencil or tips break.
- The red (positive) wire from the 12-volt car battery goes on one lead point area of the pencil. The middle shaved off area has the red (positive) wire wound about it and leading to your 4-volt phone battery.
- The black (negative) wire goes around the other end of the pencil and to the 12-volt battery. This particular wire is going to link both the negative of the car battery and the negative of the phone battery. Cut the cables accordingly.
- You can use a voltmeter to discern how much voltage is coursing where. You will see about 4 volts, which is safe for your phone battery.
- You have to manually hold apt wire strip ends to the tiny golden strips on your phone battery. You can of course tape the wires there but if you prefer standing for 15-30 minutes while it charges, no harm done. Stand the battery vertically and take negative-to-negative and positive to positive.
Put the battery back in the phone and start it up. It will work like a charm.