I just wanted to check if youc an safely charge a laptop off another main adaptor same voltage, lower power. I'm guessing no, but would like to know as I could do with being able to charge it and I only have the lower powered psu here this weekend. (Both are 19V)
You can do it. It happens all the time here at work. We use 3.36A 16V PSU for 4.0A 16V laptops. The power unit gets a little toastier than normal but we haven't had a problem with any laptops that use them. Now then... do not use a PSU that puts out more amps than the laptop can handle. We just had a laptop's charging unit go dead due to a 4.5A 16V PSU. Must have overloaded the charging circuitry. EDIT: Also keep in mind that the battery will not charge as quickly as if it had the proper PSU attached to it.
Amps dont get pushed out. It gets required by a piece of electronic equipment. So you can safely use a 100 amps powersupply on a 3 amp laptop. People do buy 500watt powersupplies for their PC's. Those things are capable of supplying more amps (since Volts x Amps = Watts), but the machines dont get fried. If Amps were being pushed out, you'd have to exactly match you PSU to your PC, but thats not the case.
