power supply - Using differently rated adapter for router?

07
2014-07
  • jimo3

    So a lightning strike seems to have blown my router adapter which had a 12v DC 2 amp output adapter.

    I am currently (no pun intended) using a spare adapter with 12v DC 1.2 amp output. This works fine for now, and I've turned the second wireless radio off just to be sure it doesn't want to draw more amps than can be supplied.

    So my real question is--suppose I used an adapter with 12v 10 amp? Do the devices draw only what they need, or would the 10 amps smoke the router? Taken a step further...if I had to in a dire emergency, could my car battery (12v DC 700 amp) be spliced to the router adapter plug and not smoke the router?

    Thanks, James

    • Answers
  • Cornelius

    The voltage should be exactly the same. Amperage should be greater because the device will draw as much as needed. Of course the power supply must be able to provide the needed current by the device. The spare adapter of 1.2A you're using now may not work in all situations.

    See this on electronics.SE: Choosing power supply, how to get the voltage and current ratings?

    If you are replacing a previous power supply and don't know the device's requirements, then consider that power supply's rating to be the device's requirements. For example, if a unlabled device was powered from a 9 V and 1 A supply, you can replace it with a 9 V and 1 or more amp supply.

  • joeqwerty

    Well you should NOT be using that power adapter.

    The current rating (amp) listed on the power adapter tells you what the power adapter is capable of supplying. In your case, the original adapter was rated at 2 amps, which tells me that the router may draw up to 2 amps, otherwise they wouldn't have provided a 2 amp adapter. The adapter you're using now is capable of supplying up to 1.2 amps. You're risking overloading the adapter and possibly starting a fire if the router draws more than 1.2 amps.

    The current rating of a power adapter tells you what it is capable of supplying. The device being powered actually determines how much is drawn from the adapter. So, in most (all?) cases an adapter with a higher current rating is perfectly OK to use. It's capable of supplying more current, but the device determines how much is drawn.

    It is NOT acceptable to use a power adapter with a lower current rating than the device requires. You will overload the adapter and could potentially start a fire.


    • Related Question

    power supply - How can I tell if an AC adapter is compatible with my laptop?
  • Jim

    Possible Duplicate:
    charging laptop with a diffrent manufacture charger

    How can I tell if an AC adapter is compatible with my laptop? For example, does the voltage output have to bee the same, or just close? What power measurements matter?


    • Related Answers
  • Robert Cartaino

    Any AC adapter is considered "compatible" with any device if it has all the following traits:

    • The voltage of the adapter has to be identical.

      It's possible that a voltage can be "close enough" because many devices are built to work within a certain voltage range. But there's no way to know reliably how your device will handle a different voltage.

    • The amperage (amps) of the adapter has to be equal or greater than the device.

      A device "draws" amperage from an adapter so there has to be at least as much amperage available as the device needs.

    • The polarity of the adapter has to be identical.

      The polarity of your adapter (and device) is usually indicated by a diagram with two circles showing a plus (+) and a minus (-) pointing to the outer plug and the inner plug.

    Of course, the shape of the plug in your device has to match the shape of your adapter so you can plug it in. If you can match all four criteria, you should be okay.

  • ChrisF

    This has been covered before, but you need to ensure:

    • the voltage is the same
    • the polarity of the tip (of the laptop plug) is the same
    • the size and shape of the tip is the same (shape isn't usually an issue as they all tend to be round, but the size might be different).
    • the current is greater and or equal to the requirements of the laptop