rMBpro 13" compatible 45w magsafe2?

Discussion in 'MacBook Pro' started by Unluckyg, Jan 29, 2016.

  1. Unluckyg macrumors newbie

    Jan 28, 2016
    Guys does this give issues? My 60w was stolen so i bought a cheap one 2nd hand but its a 45 w from a mb air.. Now i see this in wikipedia that the 45 gives only 14.5 volt? Where the other 60w would give 16.5.

    Is this a problem of will the macbook pro work slower and wont charge?
    Because now the device has got some water dmg wich was cleaned but it behaves strange..
    I can boot it but after around 17_18 seconds it will just die.. If i bypass smc by holding power and then connecting the magsafe it will boot perfectly but wont recognize battery and fan spins on full speed wich is normal in this mode.

    Now im trying to figure out where the issue is.. I measure voltage at the battery connector to be 12.5v but not consistent it will drop sometimes to 2.33 v
    Allso smc reset does turn the magsafe light to green but only for a few seconds afterwards it turns Orange

    Plz advice
  2. keysofanxiety macrumors G3


    Nov 23, 2011
    Very dangerous. Always use the same or larger wattage. 85W would be fine, 60W would be fine. 45W means you're drawing too much power from the charger, putting stress on it. Or even if it just draws what the charger can support, it won't charge your laptop properly.

    Either way, you need a different charger.
  3. Samuelsan2001 macrumors 604

    Oct 24, 2013
    Unusually have to disagree with you there,it may take a little longer but it's not dangerous. I have used my house mates MacBook Air charger on my 13 inch pro many times with no issues although if I use it at the same time it takes about 45 mins longer to charge than usual it wasn't hot or stressed in any way I noticed.
  4. Unluckyg thread starter macrumors newbie

    Jan 28, 2016
    K what i thought - its not ideal but wont change the way the rMBpro would boot etc..
    Because right now the system is dying after 17 seconds so this has nothing todo with the charger..
  5. bizzle macrumors 6502a

    Jun 29, 2008
    It's not dangerous at all. It will still only draw the same amount of wattage as the power adapter is rated for, so in this case, it'll charge slower. I used to charge my 17" MacBook Pro with a 45w adapter all the time, it would just charge half as fast.
  6. Unluckyg thread starter macrumors newbie

    Jan 28, 2016
    okay thx, i was almost buying a new charger.. but this would not fix my problem then?
    My mbpro will shutoff instant after about 17 seconds - some smc error i gues what voltage do i measure? anyideas
  7. spaceballl macrumors 68030


    Nov 2, 2003
    San Francisco, CA
    No danger at all. It will charge more slowly. I have a pro. My wife has the air. I use her charger all the time.
  8. joe-h2o macrumors 6502a

    Jun 24, 2012
    A 45W charger will charge a 13" just fine, as people have said. You'll be limited to 45W total, so in some cases you won't be able to charge the battery and run the computer at the same time. For example, if the screen is on max brightness and the CPU is under heavy load and your battery is low then the total power draw that the MBP will want to pull is more like 55W, so it will stop charging the battery in this situation or throttle the CPU down until the power demand matches the available supply.

    All Macbook Pros are able to identify what adapter is plugged into them, so they know to adjust their power requirements appropriately if they detect you have plugged a 45W into a 13" or 15" or a 60W into a 15".
  9. simonsi macrumors 601


    Jan 3, 2014
    All sounds like your battery has the issue. Just replace it.
  10. jfriedman8 macrumors 6502

    Feb 8, 2008
    I would just keep an eye out for the adapter getting too hot, otherwise I think you will be alright.
  11. Rhinoevans macrumors 6502

    Oct 5, 2012
    Las Vegas, NV
    I have been using a 45 on my 13 MBP for over a year. The charger will give what It can and the MBP will take what it gives, maybe charges a bit slower, but insignificant. I also bought a new 60, but always travel with the 45.

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