View Single Post
Old 04-09-2007, 10:39 PM   #5
photon
The new goggles also do nothing.
 
photon's Avatar
 
Join Date: Oct 2001
Location: Calgary
Exp:
Default

Quote:
Originally Posted by HelloHockeyFans View Post
IIRC, the voltage level is what can blow your device up. The higher current levels mean shorter charge periods. Can any other engineers confirm this?
The current rating of an adapter isn't what it provides, it's more what it can provide maximum. The current drawn will depend on the voltage and the resistance that the laptop shows to the adapter..

So in this case, let's assume the old adapter was running at max. V = IR, so for 19V and 4.74A that's a resistance of 4.008 Ohms.

If we take that resistance and put the new adapter's 19.5V across it, that's 4.86A, while the adapter is only rated for 4.62A.

That's simplistic though, since the resistance (and thus the current draw) will change depending on what's being used. And there's usually circuitry to regulate the voltage (though in a laptop I wonder if they offload ALL that to the AC adapter).

And keep in mind the AC adapter will be rated for full power operation of the laptop AND charging the battery at the same time. So to keep the current draw down the battery could be left out of the laptop, or keep it off while charging.
__________________
Uncertainty is an uncomfortable position.
But certainty is an absurd one.
photon is offline   Reply With Quote