Razr DIY Charge Cable Documentation
As many of you know the Motorola Razr has a built in mini-usb jack. Allowing for standard cables to plug into the jack to transfer settings and to charge the phone. However some providers such as Verizon have locked the jack requiring that special drivers be used to allow the phone to charge when plugged into a computer. The reasoning behind this escapes me. This also means that if you bought a standard USB car charge adapter for other devices it will not work with the Razr. You have to purchase the charger specifically for the Razr. Since I own a horde of USB devices having a special charger for each device simply will not do.
This project has been featured on Bit-Tech.
I recently was given a brand new wall charger for my phone, as such that opened up the idea of using the old charger as parts to build a car / universal charger for my phone. Read on to learn how I turn the Left into the Right.
Here is the completed cable, With standard usb plug on one end and mini-usb on the other. Now you may be wondering, why not use a USB cable with these plugs on it already. And to answer that may take some explaining. If you simply input 5 volts into this Razr you will get an error stating "Unauthorized Charger". This is a problem since it complicates the way the phone charges. However something interesting that I found out about the usb cable coming from the wall charger is that it has 3 wires. Black (ground), Red (+5v), White... The function of which I can only guess was to authorize the wall charger for use with the phone.
Interestingly enough if you simply connect the black and red wires to ground and a +5v source respectively the phone starts to charge and gives no error for "Unauthorized Charger". There is something about the cable that comes connected to the wall charger that is different than a regular mini-usb cable. My only guess is that two or more pins are connected on the end mini-usb plug to signal to the phone that the cable is authorized. Sort of a fail-safe should the charger fail to signal.
Simply cutting away the white wire is all you have to do. Now we can build a cable with a standard USB head to allow its use to charge on ANY desktop and ANY car usb charger. Neat huh?
At the end you get the sweet success of the charging banner on the Razr. In case you didn't read any of the text in the post and are wondering why I did this. It is because to use a standard USB-A to USB-MINI cable you need to install the Motorola Drivers on the host pc. If you tried to use the cable in the car, the phone would not charge. That is the purpose of this cable. To allow Universal Charging.