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In case of an emergency, I'd like to use my solar powerbank to charge my Macbook 2015 13". It outputs 2.1A 5V, and I learned that the MBP can be charged with that, but I don't know if that's actually true (is it?). It would take about 12 hours to fully charge it I think, which is okay

Now next problem is finding a USB to MagSafe 2 Adapter. Any ideas?

What if I use USB to USB-C, and USB-C to Magsafe 2 adapters? :) Those are readily available on the market.

Edit. I've found this which simplifies things.

Do you think this is safe? (charging mbp with 11W)

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Apple's MBP power cable supplies a maximum of 60W of power in order to both use the machine and recharge the battery at the same time.

If you're not using the MBP, then it's possible that 11W is enough to charge the battery, albeit very slowly, as you indicate.

It's unlikely that you would be able to use the machine with 0% battery on 11W, and even if you could, then the battery would barely recharge at all.

So, this might well work for the sort of emergency that required you to leave your MBP closed and plugged in for several hours until you could use it a bit.

Also: you will only draw the full power over USB C connector. USB 3.0 A connectors can only draw 0.9 A.

  • It would charge from 0% to 100% in 12 hours or so, right? (Computer is shut down meanwhile) Can this hurt the macbook? – user3722246 May 24 at 17:35
  • I'm not guaranteeing that: you claimed you had a source for that. – benwiggy May 24 at 17:40
  • Ah okay. Yes. What do you mean by "you will only draw the full power over USB C connector. USB 3.0 A connectors can only draw 0.9 A."? Sorry if thats a dumb question – user3722246 May 24 at 17:56
  • If you use an adaptor to a USB-A connector (the traditional flat one-way-round plug), then that will reduce the current that can be drawn. In other words, using USB-A will take even longer to charge, if at all. I don't know whether there are any minimum limits for the power required to charge the battery, i.e. below which the battery won't charge at all, even very slowly. – benwiggy May 25 at 8:05

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