New MB... Are My Old Chargers Useless


macrumors 6502
Original poster
Jan 20, 2010
Hi, i've just got a new MB.

My old MB is 4 years old and i've managed to build up 3 chargers (work, home, travel bag) for it over the last few years.

My Old MB uses: 85W Magsafe Power Adaptor

My New MB uses: 45W Magsafe 2 Power Adaptor

Can i use my old 85W Magsafe Power Adaptor on my new MB or will it harm the battery?


macrumors 68000
Jul 24, 2007
Troutdale, OR
Apple makes a MagSafe to MagSafe 2 adapter for just this purpose. You are also good using a higher power source 85w with a smaller drawing computer (your 45w new computer).

My wife uses an older 60w MacBook adapter with the converter for her newer MacBook Air.

One final thing I would recommend is something called a magcozy. I purchased one on Amazon, it is a leash that keeps the converter firmly attached to the power cord (also useful if you frequently switch back and fourth between MagSafe one & MagSafe 2 computers frequently.


macrumors 601
Jan 3, 2014
In my experience they all work with all Macs, the device will draw what it needs up to the limit of what the charger can give. Big machines can end up charging very slowly or not at all on the small chargers, small devices charge quickly on the big devices but the Mac won't allow overcharging as far as I can tell.


Staff member
May 3, 2009
I use an older Magsafe with my newer magsafe 2 computer. The older Magsafe connector is coming from my Apple Cinema Display, but I think its the same thing. As simonsi posted, the computer will take only what it needs :)


macrumors G4
Jul 4, 2005
MacBook: No, it uses a USB-C charger.

MacBook Pro, MacBook Air: Yes, with an adapter. It won't harm the battery.

If you have a 45W MagSafe 2 then you have a MacBook Air, not a MacBook as you said.


macrumors 603
Mar 14, 2008
Can i use my old 85W Magsafe Power Adaptor on my new MB or will it harm the battery?
It's impossible to harm the battery that way. The power adapter does not push power into the computer. Rather the computer draws power from it.

The computer'll draw what it needs, no more. You could plug it in straight into the Hoover dam if you liked, it'd still only draw what it needs.
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