60W Power Adapter on 15" MBP?

[BrewsterMccloud]

I have a 15" MBP (early 2008) with an 85W MagSafe Power Adapter.
For work I just purchased a new 13" Unibody MBP (awesome little machine). It came with a 60W MagSafe Power Adapter.

The 60W adapter seems to work fine charging my 15" machine. Is there any harm in using it this way? Will it hurt the battery?

What about vice versa - I have not tried the 85 watt adaper on the 13" machine but I'm afraid to burn something out. I'd just like to be able to use the two adapters interchangeably as I move the computers between home and work and leave the adapters plugged in.

Any advice appreciated - thanks - Brew

 

[miles01110]

Turn the MBP over and look at the small print on the back. It should say something like "Rated 16.5-18.5 V - 4.6 A max" which means you can use either the 60W or the 80W adapter.

Also, it's not bad for the battery.

 

[BrewsterMccloud]

Thanks, Miles, for your prompt and helpful response!

The 13" MBP says "16.5V/2.65A Max" on the back. I don't remember my high school physics so I don't know how many watts that is but I'd be afraid to use the higher-powered adapter with it since those numbers are lower than what you said in your email. But I'll feel free to use the lower-powered adapter on the 15" MBP knowing I won't be damaging the battery. Probably will just take a little longer to charge.

Gratefully,

Brew

 

[elfxmilhouse]

you can use the higher wattage power adapter with the macbook.

the funny thing is that they are all the same price (60w vs 80w)

I opted for the 80w for my macbook since it will work with a macbook pro if i do go with in the future

 

[miles01110]

The 13" MBP says "16.5V/2.65A Max" on the back. I don't remember my high school physics so I don't know how many watts that is but I'd be afraid to use the higher-powered adapter with it since those numbers are lower than what you said in your email.

Interesting. The HS physics you'd need to remember is

P = VI

so it looks like the 13" MBPs are now 45W, meaning you could use the MBA adapter if you really wanted to.

 

[BrewsterMccloud]

actually the 45W adapter for my partner's 1st gen Air charges my 15" MBP just fine, but it blocks one of the USB ports - inconvenient sometimes.

On the new 13" unibody MBP it looks like it would just block the Ethernet port - which I never use anyway - so that's a good option.

But I'd still be afraid of using the 85W adapter on the unibody 13" MBP since that seems to be in excess of the rating on the back of the machine. I don't want to harm the non-user-replaceable battery.

 

[mikes70mustang]

Try googling first, there are many many threads on this