1. Pdelponte's Avatar
    so i badly need to get a car charger, but i had some questions.

    Amps, watts, volts, its all a bit confusing. I have heard of phones lighting on fire or breaking when they are plugged into the wrong kind of charger.

    What are the specs (in terms of Amps, watts, and/or volts) that i should look for in a charger?

    Which ones do you like best?

    Thanks in advance.
    07-27-2012 01:20 PM
  2. wilfreb's Avatar
    Just get an OEM car charger from Samsung or motorola and youre covered.

    Sent from my GT-I9300 using Android Central Forums
    07-27-2012 01:52 PM
  3. camiller's Avatar
    Personally, in general I like the chargers than make one or two USB ports available to charge from because, between the wife, son, daughter and myself we have a variety of devices with micro/mini usb as well as *sigh* apple products with their proprietary connector.

    Now, as to amps, watts, and volts (and fire):

    First of all, a fire isn't going to happen unless either the charger or the phone is defective.

    In the beginning USB provided a maximum of 500mA at ~5v. This was sufficient for the typical computer peripherals that needed to draw power from the USB port, keyboards, mice, thumb drives and the like. Many modern devices will charge, albeit slowly, with a standard USB 1.0 port.

    In 2007 the USB Battery Charging Specification was introduced which muddied the water considerably. This spec provides for two different types of higher power "charging" ports. The first type allows data transfer at the same time as charging and has a limit of 900mA above which too much interference was generated on the data lines. The second type allows up to 1.5A without data transfer. In order for your device to know what type of port it is plugged into it looks at the data lines. If the data lines are shorted together your phone knows that it is on a charging port and can draw as much power as it wants up to 1.5A. If the data lines are not shorted together there is a specified negotiation protocol for the device to determine if it can get 900mA or 500mA. I believe the GS3 will draw 700mA max, at least I think in another thread someone mentioned that the included charger had a 700mA rating. I get my GS3 Aug 1.

    Now our conversation must take a darker turn. Some companies (apple) use a non standard way for the device to know how much power it can draw, looking for specific voltages on the data lines to let their devices know when they can pull up to 2.1A in the case of an iPad. Because the various iDevices are (for some unfathomable reason) very popular many accessory makers, including makers of car chargers, want to cater to that large user base. So it should come as no surprise that many car chargers are advertised as capable of delivering 2.1A but when used with standard devices the device will not know they can draw more than 500mA.

    So, even if the specs SAY it can produce plenty of power our phones won't necessarily be able to detect it and use as much as they otherwise would. Ultimately, since specs won't really tell you everything you need to know, you will have to rely on comments in Amazon customer reviews, and recommendations from others here on the forums and elsewhere to point you to devices that will work well.

    For my current phone (Palm Pre) I have this: Amazon.com: PowerGen Dual USB 2A 10w (fast) Heavy Duty Ouput Car Charger - Black: Cell Phones & Accessories. But be aware that of the two ports, one is marked 1A and the other is marked 2A. The 2A port is designed for Apple devices and won't deliver full power for non-apple devices. The 1A port will deliver the full power to non-apple devices, in fact all the way up to 2A if nothing is plugged into the other port. There is a really good write up in a user comment on the white version here.

    I've seen other people recommend Amazon.com: Griffin Powerjolt Dual Universal USB Micro: MP3 Players & Accessories but comments there make me think there are at least two hardware revisions of this product and that at least one version won't work well for our phones without modification.

    Hope this helps.
    paradroid and akbled like this.
    07-27-2012 02:35 PM
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