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I have two AC adapters and I want to know if I can interchange them. One says +12V = 2.0A and the other says 12V = 1.5A.

The equal sign is not actually an equal sign. The bottom line is actually three dashes.

Mike
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2 Answers2

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There are four things that have to match for a simple DC power supply to work safely:

  1. The connector. If the power supply doesn't have a connector that will physically connect to the device, it obviously won't work.

  2. Polarity. The power supply has to provide the positive and negative sides where the device expects them.

  3. Voltage. The power supply has to provide the voltage the device expects. Generally, being within 10% is sufficient.

  4. Current. The power supply has to provide at least as much current as the device requires. Being able to supply more is okay.

So if the connector and polarity are the same, a 2A power supply can be used on a device that only require 1.5A. The device will draw the amount of current it needs.

David Schwartz
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    further: (1) volts times amps = watts, so if the device requires 12 watts, @ 12volts, you need 1 amp. (2) there often is a diagram with a little circle connected by a line inside inside a "C". This usually is the polarity diagram. Compare against: https://en.wikipedia.org/wiki/Polarity_symbols – Yorik Feb 24 '16 at 19:33
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It depends on the current requirements of the hard drive. These should be found on the drive itself or in it's documentation.

If it requires less than 1.5A, using the new 12V/2A adaptor may be okay. If more than 1.5A then no it won't work correctly.

Basically, whatever adaptor you use has to be rated for more current than the hard drive requires.

If you run it from an adaptor with too low a current rating, it is very unlikely to harm it, it will probably just not work reliably. Current requirements rise and fall depending on what it's doing so this would be intermittent, you can't just plug it in and see if it "works".

That said, a 2A device is different than a 1.5A device and you should use what is supplied from the device as using the incorrect power adaptor could potentially destroy your device and void any and all warrenty.

Matt King
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