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How to know the charging/discharging speed of your MacBook

I recently encountered this problem when the charger of my MacBook 11” was stolen in the library. I had to use a USB charger for my Samsung Galaxy to charge the laptop with a micro-USB to USB type C converter. Obviously it wasn’t quick enough so the net effect on the battery was discharging. I have a few phone chargers, and a portable battery, so I would like to know the charging/discharging speed.

After some Googling I found the system command system_profiler. It lists all the system information about your Mac. To follow the following instructions, you need to have Terminal (Launchpad-Other-Terminal) opened.

First I’ll use a MacBook Pro 15”, mid 2015 as an example of displaying the discharging speed.

The charging/discharging speed is basically indicated by the battery current. If it’s negative it means your battery is discharging and vice versa.

I fully charged the laptop and waited until the battery went to 99%. I then did

system_profiler SPPowerDataType

and saw the following information about the Battery.

Notice the Amperage (mA) and keep in mind that it might change a little based on your activities but it should always be negative if you don’t connect to a charger. You should repeat this a few times to get a rough estimation about the basic power consumption of your laptop. If you don’t want to see so much information but only the Amperage, use

system_profiler SPPowerDataType | grep -I "Amperage"

Typically there will be some delay but it doesn’t matter. See example below

Now if I connect the charger (85 W) it shows a positive Amperage indicating a fast charging

The estimated Amperage of a MacBook 11”, with minimum activities (only Chrome opened and no “significant energy usage”) of different chargers are:

  1. A Samsung Quick Charger (for Galaxy S7 edge) + nanoUSB cable + nanoUSB to USB C adapter: Roughly -200 mA. Even though you turn off the laptop, charging speed is super slow.
  2. A Samsung Quick Charger (for Galaxy S8 edge) + USB C cable: Roughly 0 mA (so if you turn off the laptop it should be charging quickly enough).
  3. A Samsung normal charger (for Galaxy S6 or earlier) + nanoUSB cable + nanoUSB to USB C adapter: Roughly -300 mA. Even slower than 1. Almost not visibly effective charging.
  4. A portable battery, marked up to 5 A: Roughly -100 mA. Slow but useful.

So, if you lost your original charger, you may use a Samsung USB C charger and its cable and shut down your computer for temporary rescuing. Or, you have to buy a good charger from Amazon…

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美高校毕业生申请OPT攻略 – 言简意赅无废话!

什么是OPT

Optional Practical Training (OPT), 就是让学生毕业后能留美工作的手续

谁能办OPT

本文主讲毕业生办OPT的流程。但在读F-1学生也可以申请pre-completion OPT,只需要在学校呆满1年即可。毕业生办post-completion OPT.

办OPT顺序

  1. 大概毕业前3,4个月的时候,跟老板确定大概哪个月份毕业。假设定5月1。注意是毕业时间不是答辩时间!答辩在毕业前,之后要交论文稿件预留时间;

  2. 跟学校international office说一下,要求开始出具OPT的证明。IO会咨询老板意见,老板confirm。IO给你一个新的I20,上面指明是给OPT申请用的。会有一个targeted graduation date;

  3. 毕业前3个月的时候(最早90天前交材料),把材料寄出:需要的材料quote如下: 

    To complete your OPT application, please do the following:

    • Print your name, sign, and date the I-20 where indicated.
    • Make a copy of the I-20 once you’ve signed it. You will keep the original and the copy will go in your application packet.
    • Assemble the OPT packet in the following order: o   I-765 (top page) o   Page three of I-20 copy o   Page one of the I-20 copy o   Copy of your passport identity page o   Copy of your paper I-94 card, front and back OR print out of your electronic I-94 record
    • Staple your bagged passport photos to the upper right corner of the I-765 only.
    • Staple your check/money order to the top center of your I-765 only.
    • Staple the entire packet together in the upper left corner.
  4. 寄出材料。与此同时,准备答辩材料,开始找工作,跟公司说明5月2号之后可以工作。公司HR会明白,发offer的时候上面start date会写5月2号或者之后,但最好不要太晚,因为OPT期间失业天数有限。如果start date是5月11号,但5月1号拿到了EAD卡,这10天就是unemployed status。

  5. (难点): 假如file太晚,毕业之后还没拿到EAD卡,这段时间都算失业期,即使批准了还没到手也算;file也不能太早,90天限制。

  6. 4月某天答辩,催一催USCIS,大概5月1号或者之后拿到OPT EAD card,去公司报道。

注意 先跟老板沟通好毕业时间。毕业时间决定了答辩时间和申请OPT的时间。OPT批准时间多则2,3个月,邮寄等等都需要count在内,不可轻视。宁可早点拿到不要晚。OPT加急非常麻烦,一定要早点行动。