Advanced Battery Pack From Cell Phone





Introduction: Advanced Battery Pack From Cell Phone

Want a great use for you old phones sitting around? Sure you do. I have the perfect solution. Turn them into rechargeable battery packs.

Parts and Tools:

1. Screw driver
2. Soldering Iron
3. Multi-meter
4. Solder
5. Flux
6. Wire cutters
7. Knife or razor

Note: A battery with a protection circuit is advisable to make sure you don't discharge the battery too much.

Step 1: Find Charging Terminals

1. Take the phone battery back off
2. Take out the battery
3. Plug the charger into the phone
4. Take a multi-meter and find the positive and negative terminals

• Most phones have 2 to 4 terminals that connect to the battery and are clearly labeled.
• Most likely you will have a +, -, and T. The + is positive, the - is Negative, and the T is a temperature terminal

Step 2: Solder

Solder your wires, or plugs, onto the terminals that you found to be positive and negative. try to solder to the outside surface of the terminal (the one that makes contact with the battery). You may have to take a knife or razor and carve some of the plastic away in order to allow the battery to fit while the wires are soldered.

Step 3: Replace Battery and Back

Put battery back into the phone and use your multi-meter to test weather or not you are receiving voltage which means you are receiving current through the wires. If yes, then plug the phone charger in and see if you are able to charge the phone.

Locate where the wires are coming out of the phone and cut or drill an appropriate hole in the battery back to allow for the wires to be accessed.

Step 4: Test

Test and see if you are still getting voltage and current.

Step 5: Thoughts

This is a great little mod because it allows you to use a phone that you otherwise would not. It is great for running an Arduino mini or other small item. The best part is that it has alarm functionality, a clock, and a great battery bar. I have done many phones and have had great success.



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    Now my old phones finally come in handy, thanks for sharing this with us.

    I am trying to replicate it but it is not working, when I solder the wires on the connectors I lose voltage, and when I remove the wires the phone works again, is possible that the solder I use is not conductive?

    Maybe use a multimeter to check if there is a short circuit?

    "Put battery back into the phone and use your multi-meter to test weather or not you are receiving current through the wires. If yes, then plug the phone charger in and see if you are able to charge the phone."

    Actually, unless you are testing the T-terminal, and not either the Positive or Negative terminals, you would be testing whether or not you are receiving current through the wires. Nice weather we're having, innit? ;~0

    Also in this case since you are checking continuity, you are checking for a potential voltage difference and not, strictly speaking a current, which - in order to test - would require a break in one arm of the circuit in which to place the ammeter or current rate (amperage) of the circuit under test - the battery and the wired connection to the terminal side you are checking - either the Red (positive wire) or the Black (negative - or Ground wire) that you have just soldered.

    It might be good to point out that measuring current is a serial operation, requiring an actual break to see the rate of flow being measured by the meter while it is being placed in a serial connection between one side of a broken wire and the other break in that same broken wire.

    Voltage, which isn't the same as current since it doesn't measure a rate of electron flow, but instead measures the potential difference between one point and another in a circuit, is a parallel operation; one test lead goes to one terminal and the other test lead goes to the other terminal: the two points in the circuit between which you are measuring the potential difference in units of Volts or fractions of volts. This difference is measured on the Volt scale and is, in this case would be by touching the Positive Terminal with the Red or Positive Test lead. The other test lead (probably Black in color) would be attached or touch the Negative terminal or circuit Ground point. You would be measuring the number of Volts of potential difference between the two sides of the circuit that make up the Battery. You can measure circuit continuity by attaching the test lead to any part, component or wire that is attached to the circuit terminal or polarity under test. This will tell one if the solder joint creates a good bond and is at the same potential at both ends of the wire being tested for continuity. Unless the wire in question being used is very thin (consequently having a high resistance that can create a potential difference like would be caused by inserting a resistor in-line with the test lead), the measurement of voltage at either wire end would be practically speaking the same.

    Sorry for being so verbose, but I thought it important to make that distinction. Voltage and current flow are principles of electricity and electronics that make their understanding crucial at a fundamental level. Many people struggle with these basic principles for years until a full comprehension is reached.



    It was a general statement. Current sounds better than voltage. Ohms law shows that if there is voltage (using the multi-meter) then there is current. I had faith in the intelligence of those reading the instructable to know this. Thank you for your comment though.

    "Current sounds better than voltage" ?? That's like saying "cheese" sounds better than "cat" (which, in fact, it does but that is besides the point). They are very different concepts, and only serve to confuse the reader if you mislabel them in the way you did. It does you good *not* to rely on the intelligence of the reader, especially by the people new to electronics who might mistakenly use your instructable as basis of learning. Other than that, keep up the good work!

    Yeah, this point has already been made and cleared up. If I would not have corrected the problem then maybe your point would have been welcome, but with new information and taking the constructive criticism to heart I fixed the issue. That has to at lease keep someone from making the same point, made earlier, right? Thank you for your comment though.

    Cleared it up on the Instructable

    Are you certain the (low voltage) protection circuit is in the battery and not the phone? The the older phones I had were not built this way.

    If you discharge the battery from these wires does the protection circuit isolate the battery at around 2.7-3.0 volts?

    Every phone I used had a lithium battery with a protection circuit in the batery. I am sure that not all batteries do. I would advise making sure yours does.