61w charger with 15" Touch Bar MBP

Discussion in 'MacBook Pro' started by XSharp, Nov 24, 2016.


Is it okay to use a 61w charger on the 15" Touch Bar MBP?

  1. Yes, it will just charge slower

  2. No, could damage internal battery

  3. No, could damage charger and be dangerous

    0 vote(s)
  4. Other (see comments below)

    0 vote(s)
  1. XSharp macrumors member

    Nov 24, 2016
    Does anyone have experience using the 61 watt charger originally intended for the 13" MBP with a 15" Touch Bar MBP? I use the 87w adapter at home but am looking for something lighter to take with me during travel. I know the 61w model may not be able to keep up when the 15" TBMBP is under full load and will generally charge the computer at a slower rate. I am accepting of this. What I am more concerned with is if use of the 61w will damage the computer's internal battery or overheat the charger. I'm also unsure of the amperage rating on these chargers.
  2. 3JL macrumors member

    Mar 29, 2016
    I am also very keen to understand this! But more in relation to monitors that have max 60W power throughput.
  3. DanDilla macrumors member


    Nov 15, 2016
    Lüneburg, Germany
    Should be fine, like in the old generations, where you also can load your 15" with a 13" charger (was like 85 and 60 watts).

    Also it's not as healthy as chargung with the 85w charger, but this could be just a rumor, as i am not an engineer and don't have a reliable source.
    And of course it's loafing slower.

    but with the usb-c power delivery it sould be fine, just loading slower.

    But i'm curious if it really affects the battery in any way.
    Especially with the possibilities of using powerbanks with 20w or even less!
  4. MadDane macrumors 6502a

    Apr 5, 2015
    With the previous Magsafe I have used 45W, 60W, and 85W interchangeably between MacBook Air, and 13" and 15" MacBook Pro's. No issue there. I don't see that why that would be any different with the new ones. They draw as much power as they can but no more than the power supply can supply. But here it should be said that I haven't tried myself on the new ones.
  5. daveak macrumors 6502

    Jun 28, 2009
    Durham, UK
    Probably depends on the load you are putting on the machine to if it will actually charge. I've tried putting power through a 60 watt hub, and noticed by battery was draining slowly when pushing the graphics card heavily.
  6. viljamip macrumors regular

    Jan 22, 2016
    The USB-C standard has a smart power negotiating system. When you plug in anything that can provide power, the power source and your MBP negotiates what voltage and current they both can handle. Charging your battery a bit slower is actually beneficial for its life so no problems there either. Just prepare for slower charge time / battery slowly draining under high load.
  7. XSharp thread starter macrumors member

    Nov 24, 2016
    Agreed...it would be nice to understand the impact of using even lower wattage adapters. Could be very advantageous for travel when the laptop can be used on battery power and then charged overnight on an adapter of small size/weight while the computer is in standby and not under load. I carry a lot of gear while traveling and the extra grams of weight add up!
  8. shareef777 Suspended


    Jul 26, 2005
    Chicago, IL
    This. I use a USB-c adapter that limits the charging to 60W from my 87W charger. No issues with this. No issues here.
  9. npreq macrumors member


    Nov 23, 2016
    It will never be a bad thing per se, or at least I can't imagine how it could go wrong. However, if you start doing intensive stuff that puts the overall power load more than what the charger can provide, you'll start to lose power since the charger won't be able to cope with the load. But that's regulated by the SMC (and the usb-pd protocol), so there's no risk of the charger heating up or overloading. At least in theory. You'll probably see some info on the battery icon that it's not charging if you go over the power draw.
  10. XSharp thread starter macrumors member

    Nov 24, 2016
    Update: After 2 weeks with using the new 61w charger everything seems to be OK. Under heavy load the charger can't keep up and the battery slowly depletes, but I usually use the laptop on battery power and then charge while the computer is not in use. Due to the fact that most of what I do is light use during travel, with relatively short periods where the CPU is pushed, I have a 29w charger on order. The tradeoff of size/weight versus charge capability is worth it to me.
  11. xraydoc macrumors demi-god


    Oct 9, 2005
    I've used my 15" on the 29w charger as well as the 61w charger. Both work fine.

    The 29w machine will even charge the machine if the usage is light. But don't expect to rapidly hit 100% while using it. And charging it from a nearly depleted battery even while off takes a good long while.

    The 61w charger is almost as good as the 87w version and will even keep up with the laptop in use under all but the most serious of combined CPU/dGPU loads in my experience.

    The standard 87w adapter, however, charges the machine remarkably fast, even when in use.

    If I were traveling, I'd probably want to take either the 61w to save some weight or just take the standard 87w (only slightly larger physically than the 61w), since if I need to top off the battery (say at an airport or a Starbucks or something), I'd want to be able to do that as quickly as possible. While charging overnight with the 29w adapter isn't an issue, a quick battery boost during a short layover isn't something you should expect from it.

    Edit: That said, I tend to carry the 61w in my laptop bag to save a few ounces of weight. I keep the 87w at home (so I can quickly charge then use on the sofa without wires) and another at work.
  12. 537635 macrumors 6502a

    Mar 7, 2009
    Slovenia, EU
    Thanks. Great info and really pleasant surprise, that the new Macbooks are so versatile when it comes to charging.

    So 29W is actually enough to keep the machine topped up with light work (Pages, Safari, Keynote)? That would actually bring the weight of the whole package (15'' Macbook + charger) down to the previous 13'' with it's 60W charger.
  13. 537635 macrumors 6502a

    Mar 7, 2009
    Slovenia, EU
    Could someone please try if the 29W keeps the 15" charged and at the same time charges an iPhone.
  14. XSharp thread starter macrumors member

    Nov 24, 2016
    I've only tested this briefly but here's what I found: When my iPhone 7 is plugged in and the MBP 15'' is at full screen brightness under light load (Safari browsing), the phone charges but the computer simply holds steady. Once the phone battery reaches ~100% the computer's battery charge level begins to rise.
  15. 537635 macrumors 6502a

    Mar 7, 2009
    Slovenia, EU
    Thank you.

    Now I'm only thinking how bad this is for the computer's battery. For instance on Anker's webpage it is written, that they do not support passthorugh charging (charging the battery AND the phone), because:

  16. poorcody macrumors 6502a


    Jul 23, 2013
    Without knowing any specifics about this battery or the USB-C specs, in general, charging a battery more slowly is actually better for it. The only danger would be if you are charging and drawing from the battery simultaneously -- i.e. if your power draw rises and falls above what the power-adapter can supply as use go along. This is generally very stressful for a battery (which I think is the point of the Anker webpage reference).
  17. XSharp thread starter macrumors member

    Nov 24, 2016
    While traveling I regularly draw more power than my 29W adapter can draw, though generally for short periods. No issues so far, I am experiencing advertised battery life. We'll see how it performs over the long term.
  18. asiga macrumors 6502a

    Nov 4, 2012
    Sorry to wake up this old thread from 2 years ago, but what have been your experiences with the 29W adapter and your 15''MBP? Was the 29W a good choice? Did you keep using it? I have a new 2018 15''MBP and I'm also looking for the lightest -in terms of weight- alternative to the quite heavy 87W adapter from Apple... (you can see my thread here)

    Also, did you measure the weight of your 29W adapter? What's its weight? Do you have some link to any store selling it?

  19. recurrence macrumors member

    Jun 29, 2012
    I've been using the 29W with a 15" on occasion. For extremely lightweight work like code editing (no compiling or interpreting), and some safari usage it remains charged at 100%. Otherwise, it begins to drop and precipitously so if heavy compilation is underway. The CPUs in these machines are 45W+ after all.

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