Which power adapter should have come with my 15" Macbook?

Question

I got a 15" Macbook Pro at Christmas this year and I just looked at my power adapter and saw that it's a 60W, although I thought it should have been an 85W one. My computer does charge when I'm using (and rather quickly too, I might add), but I was just kind of wanting some clarification on this. I'm looking to buy a second power adapter to have one at my house and one at my boyfriend's house. He currently is using a 13" black Macbook (circa 2006, I believe), but is looking to get a 15" Macbook Pro in the future.
Anyway, I'm just wondering what power adapter I need to purchase, and check that I was indeed given the correct charger to begin with. I don't know how to find my model number, but it was the cheapest of the 15" models at the time. Thanks for your help!

Answer 1

Eh, not quite: You can use any Intel MB with any Magsafe adapter, but the use of it will vary.
I use my 17" mid-2010 i7 MBP with a 60W adapter from time to time if it's the one in a convenient place, I've even used it with the 45W only Airline adapter. Note the MacBook's power system is quite smart. If the system is on and active and it needs to restrict the power drawn, charging the battery will be the first to go, and then external power will be supplemented by battery power. So with a 15" or 17" MBP: on an 85W adapter you can play a 3D game and charge at the same time. Whee! Charge time is lessened if you draw less power and minimized if you power off the system and only use the available power to recharge. On a 60W it's possible to draw enough power using the system that charging will take an impractical amount of time. Power the system off and it'll recharge almost as fast as the 85W. With a 45W or airline adapter it won't recharge at all, and if the system is pretty busy, power will be draining from the battery too, albeit at a slower rate than if you were on battery only.
Think of the MacBook's power system as a water tank with an inlet hose and a drain hose. Inlet hoses come in three sizes, if your inlet is larger than your outlet you can fill the tank (recharge) at different rates depending on the drain (Air, 13", 15", 17" and how busy). The only exception where the analogy breaks down is if your drain is not the smallest (Air) and you use the smallest inlet (45W adapter), you can't fill the tank even if the drain is closed (MB is off).
If you want the other gory technical detail, only the 85W Apple adapter can switch up the 16v to 18v to allow for a faster recharge on the 15" and 17" MBP.
Probably more than you wanted to know...
Bottom Line: If you want to be able to charge any MagSafe MacBook, get an 85W adapter, Apple charges the same for the 60W as the 85W, and the 85W is only a little larger these days. (3rd party Magsafe adapters, not so much, the 60W's are usually a few bucks less.) 85W is what you'll find at the training tables in an Apple store BTW.
Don't bother with the $50 airline adapter if you don't own an Air. There are several 3rd party Auto/Air MagSafe adapters that will charge a 13" -17" MBP in the air or on the road.
James