This question may sound senseless but I am novice, just looking for clarification. My Cordless phone has a Wall wart AC Power Adapter rated at 9v 500mAh. As far as replacement is concerned, does output power only matters or we have to be specific with ratings also? Like a 4.5V 1A adapter output will also be 4.5W as original rating. I have read in this forum that higher current rating may not matter but higher voltage may damage. Also, I have heard that SMPS based supplies senses the actual load and outputs accordingly. Please correct me.

 

You can use an adapter at the same voltage and higher current, but no other voltages or lower currents are likely to work.

 

In case this is seen as a place where one must get multiple and even some conflicting answers, too bad.

dl324 is right on. Do not vary on the voltage rating by more than a few percent! If you can't find the same ratings as your manufacturer supplied one, try to stay close, and err only very slightly lower on output amperage if you must, but going a bit higher on amperage will probably be more acceptable to you. Monitor your equipment carefully the first time you use that different one, to be sure you do in fact get a charge, but things don't get too warm.

I use my mfr. supplied charger in my car (plugged into that cars inverter) because it's a fast charger, but an older lower amperage charger in my room for overnight charging. The fast charger provided with my phone gets things hotter than I would typically be comfortable with, but it is intended to be a "hot charger", so I tolerate it.

 

Wall warts are all over the place when it comes to voltage. Some depend on sag as part of their specs. I have a 12V 1A WW that unloaded delivers almost 14VDC. I tested it with a 10 ohm power resistor and got 12.6VDC. It may not matter that much in most applications but I'd say a cheap battery charger deserves closer scrutiny.

 

In your original post you used the units "mAh", or milliamp-hours. This is nonsense because it is a rating for a battery. A wall wart should be rated in watts or volts and Amperes.

 

Yes, mAh was a typo, its miliAmp only. Fine I will go with same volts and a bit higher amps. I have a 120v/60Hz wart so can any modification be made inside the wart to get an output of 220v/50Hz or I have to use an external converter.

 

Yes, mAh was a typo, its miliAmp only. Fine I will go with same volts and a bit higher amps. I have a 120v/60Hz wart so can any modification be made inside the wart to get an output of 220v/50Hz or I have to use an external converter.

Depends on the wall wart. Some can work just fine under either input with no mods (other than a plug converter to fit the outlet). Others will go up in flames. Not all wall warts are made the same.