Power Supply Limitations Question

[cgcmgr 0]

Hi,

 

Let's say I have a 12V 1A power supply, but the device I have it powering is 12V 2A. What will happen? Will the device just not power up or will the power supply burn out? If it burns out, can it be a fire hazrad?

 

Thanks,

Chris

[jack in oz 0]

The fuse may blow (if it has one) or the voltage will drop to an unusable value. In short, it won't power the device properly.

[Soundy 1]

Also, it MAY kill the power supply, depending on how robustly it's built... but it shouldn't be a fire hazard. It will just let the magic blue smoke out of a couple components and the thing won't work anymore.

[jondilly 0]

I very likely will damage both devices if the full 2A is actually drawn. If your device is rated for 12V 2A, then it will consume 24W DC. If your power source is unfused and is rated for 12W DC (12V x 1A), then the voltage will sag due to the lack of power, which will in turn require more amps to keep the total watts needed by the device. These extra amps are what will burn up your wire if it isnt rated for the extra amperage.

[Soundy 1]

These extra amps are what will burn up your wire if it isnt rated for the extra amperage.

Where are these "extra amps" going to come from if the power supply can't provide more than 1A? Plus, it would have to be a very thin wire indeed for 2A to "burn it up".

[mike_va 0]

May provide more than an amp for example depending how the protection is setup, and the exact nature of the overload.

 

Keep in mind not all these cheap supplies are UL listed - and may very well be a fire hazard when overloaded. What UL refers to as sustained flame, as opposed to a little smoke.

 

Not a good idea. You can get the correctly rated supply fairly inexpensively, and give yourself some margin - don't run a 2A supply at 2A.

[the toss 0]

I very likely will damage both devices if the full 2A is actually drawn. If your device is rated for 12V 2A, then it will consume 24W DC. If your power source is unfused and is rated for 12W DC (12V x 1A), then the voltage will sag due to the lack of power, which will in turn require more amps to keep the total watts needed by the device. These extra amps are what will burn up your wire if it isnt rated for the extra amperage.

 

Ohms Law 101 - If the voltage decreases & the resistance stays the same then the current will DECREASE

[J-Telectro 0]

One word of warning...

 

Don't assume that because the supply voltage to a device is low that the required input current

also goes down. Most modern electronic devices use internal switching regulators and with these

the opposite is true...as the input voltage to the device drops, the input current increases.

 

As everyone has said make sure you have a supply that is rated for your device.

 

John