I have an old laptop that's missing the AC adaptor. Can I use an adaptor that outputs 13V-5A to power a device that uses 13V-2.77A?
I guess this might be a stupid question, but I never had to find a replacement AC adaptor before. So I thought I'd ask before I end up frying the laptop.
Yes, you can.
In layman's terms, the device (laptop) will only "draw" so much current (amperes) that it requires.
However, you cannot do it the other way around and the voltage must be the same.
Just double check the polarity as well. Some obscure devices had their polarity switched around (positive on the "outer" side and negative on the "inside").
Thank you.
The laptop doesn't show the polarity anywhere, but I have found a manual online and I hope the information will be in there.
Besides the polarity, the other caveat is that it should be a regulated supply, meaning that it will always output 13V regardless of load. Cheaper and older supplies frequently aren't regulated and their voltage starts out a lot higher than what's marked. The voltage then drops gradually in relation to how many amps are being drawn. That's okay for some devices but a laptop might not like the input voltage to deviate from what was intended.
If it's labeled as a "switching" supply then I believe it will inherently be a regulated type.
If the supply is OEM from another laptop then it's probably well regulated and quite safe to use.
If you have a multimeter then it's easy to just check the voltage at the plug. If it's regulated then it will be at the correct voltage without any load.
wrote:Besides the polarity, the other caveat is that it should be a regulated supply, meaning that it will always output 13V regardless of load. Cheaper and older supplies frequently aren't regulated and their voltage starts out a lot higher than what's marked. The voltage then drops gradually in relation to how many amps are being drawn. That's okay for some devices but a laptop might not like the input voltage to deviate from what was intended.
I know you are talking in generalities, but do they even make ureg supplies that are anywhere near the amperage range you would need to power a laptop. In my experience ureg supplies were typically only made in low amperage (less than 2A) and typically come in output voltages more suitable for running 5v linear regulators (7-10V) or if they were a higher voltage it was usually at fairly low amperage for powering tool battery chargers. The higher amperage ureg supplies seem to have huge transformers inside , for higher amperage designs 2A+ , I think manufactures realized they didn't have to use large expensive transformers and they could cut down on weight and thus shipping costs by using switchmode supplies.
wrote:I know you are talking in generalities, but do they even make ureg supplies that are anywhere near the amperage range you would need to power a laptop.
I'm not sure. Perhaps not. 😀
The adapter I found is labeled "switching mode adapter" so I think that should be ok.
