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MacBook Pro Battery Case

I am working on a shell style case for a MacBook Pro that will charge the laptop on the go and adapt USB C to other ports

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My idea is to make a shell style case for a MacBook Pro laptop. The main feature of the case is that it will have a battery pack built in to charge your laptop about 3 times over. It will also, through the one plug, adapt to multiple USB type A ports an SD card reader and multiple USB C passthroughs. The case itself will charge via one of the downstream USB C ports and the case will charge and transfer data to the laptop via another USB C port. This would enable charging of the laptop from the case at maximum USB Power Delivery speed while also transferring data from the USB ports and full-sized SD card reader built into the case.

If you could give this project a like I would be extremely grateful and would help bring this project to life!

The Problem

Every day, I bring my laptop to school. I am working on my laptop all day, wether it be just typing simple word documents for English class, using photoshop and illustrator in digital art, clacking away on my computers calculator for math, CADing in Fusion for robotics, or watching YouTube videos for biology. Inevitably I, along with every other one of my class mates, patiently wait and pray we don't see the devastating notification that our Mac is about to run out of power. To no avail when the notification pops up, we jumble through our bags, unravel our charger, and race toward an outlet to beat the time bomb of our computer powering off. We all then attempt to plug the charger into our laptop only to realize the outlet is just a foot too far. Now we have to pick up our laptop and bag, relocate to another desk and finally, when we get the change to deliver juice to our ever thirsty laptops, It has died...

Now we sit there for three to five minutes as the laptop charges enough to reboot up and we hope everything resumes back to normal operation to finish our work.

If you are like any of my peers and I, we can easily go through two full charges, if not more, before we have finished our homework at the end of the day. One day while I was extraordinarily frustrated of my laptops lack of power through the day I thought there must be a better solution. 

While my dead laptop was charging I did the first thing any reasonable person on the internet would do. I pulled my phone out of my pocket and searched amazon for an external battery for my laptop. While I did find what I was looking for they were extremely bulky and super heavy. 

In an even greater feat of frustration I dropped my phone and then it hit me. I had always kept a charging case on my phone to prevent it from dying halfway through the day. And I thought "WHY DON'T I HAVE ONE OF THESE FOR MY LAPTOP!"

My Project

It was in this moment I knew my fate. I needed to design and create an easy to use case for my laptop that would contain a battery in order to help me and others get through the day easily without running out of charge. I also believe it would be extremely useful to include USB C docking station features such as Type C to Type A converters (so we can plug old fashioned usb devices in), an HDMI output to plug the laptop directly into an external display, and an SD card reader because many professionals who use cameras dearly miss the SD card reader on modern laptops.

Now, if my story above has enraged and delighted you so much as to finish my detailed account of a daily struggle so many of us face. Please follow my journey below, comment when you have an idea to help, and help me bring this idea to life.

  • Lets Begin the Long Road of Research

    Harrison Freedman04/10/2019 at 14:05 0 comments

    The current MacBook Pro 13 inch has a battery capacity of 58 watt hours and In order to charge the laptop 2 times the battery pack needs to have a minimum capacity of 116 watt hours (very tough math I know). 

    This is the point in time where I started doing research into battery chemistries and the pros and cons of each battery type. At the bottom of this post I will provide hyper links to all of the research I have done. I will include the specific research I had to do for lithium ion batteries such as their capacities, charging and discharging abilities, safety, and what their data sheets actually mean. When describing the parts I will order I will go over their brief purpose but I highly recommend reading all of the links at the bottom of this post. 

    Through my research in order to achieve the capacity desired within the size of the MacBook Pro frame I knew I was going to need lithium ion batteries in the shape of a pouch not a cylindrical cell. I searched online and found this lithium ion battery that will work well. The single cell has a capacity of 48 watt hours. In order to achieve the capacity desired I will use three of them in series because this will allow faster charging than parallel and achieve the desired minimum capacity. 

    Because the battery pack will be a three cell lithium ion pack I need to balance charge them. Balance charging ensures the pack will receive a safe charge (preventing a Samsung style battery problem). The same balance charging board will also prevent over charging and discharging because lithium batteries are super sensitive. I settled on this balance charger because it can handle charging the batteries as quickly possible and will not be destroyed by discharging the batteries quickly.

    The other difficulty is that in order to charge a three cell battery pack you need to deliver a constant 12.6 Volts  (each cell needs to charge at constant 4.2 volts). This proposes a difficult challenge because no wall sources (that I currently own) will provide a constant 12.6 volts. Therefore I need to convert whatever source I am using to 12.6 volts. I’m going to achieve this with this variable voltage converter set to 12.6 volts.

    As for the wall converter (AC to DC) I am just going to use a spare large 12 volt wall plug (it can pump out 8 amps or 96 watt hours total). I am doing this because in the near future I will provide power using USB C. For now the proof of concept of being able to make my own lithium battery pack (and able to charge and discharge) is satisfying.

    I think it is also extremely important to mention that normally when designing battery systems with lithium ion batteries you need to pay careful attention to how quickly you can safely charge the pack. These specific batteries can handle up to 12 amps of power during charging. This enables lots of overhead especially because USB C (using power deliver protocols) can only provide up to 100W (well within the capability of the batteries). Therefore in my situation using the wall wart which can only provide 96 watts I’m well within the power rating to safely charge the batteries.

    Here are some of the super useful links if you want to build a battery pack of your own

    All About battery types

    A lot about Lithium Batteries

    Charging Lithium Batteries

    More on charging

    I recommend reading as much as you can before you embark on building your own battery pack.

  • Here's a Drawing of What I Would Like the Case to Look Like

    Harrison Freedman04/10/2019 at 00:59 0 comments

    I did a basic drawing of what I would like the case to look like and how it will clip in. I also added a description of where the ports are located and their individual purposes.

    As I hope my drawing conveys It will clip into the rear first then hinge forward to clip into the front. After the case is secured the custom C shaped type C cable will connect the furthest to the rear USB C ports together to transfer data and charge between the laptop and case. Im not sure what I would like the case to be made of but I think a rubber or silicon coated plastic would be super nice.

  • What Exactly is the Goal?

    Harrison Freedman04/09/2019 at 02:06 0 comments

    Lets just jot down some basic goals that I would like to accomplish

    1. Able to recharge laptop from dead at least 2 times
    2. Use only one USB C port on the laptop
    3. The one connecting USB C cable will be able to transfer power and data through the one port
    4. The case is able to charge at the full 100W capable of USB PD
    5. The case can deliver up to 100W of power to the device
    6. one downward facing USB C ports able to charge case and read data (thunderbolt capable)
    7. Two downward facing USB A ports 
    8. Full sized SD card reader
    9. HDMI output

    I will be breaking down working on this into two major subsections. First, the battery component and being able to charge it via USB C and then charge a laptop from the battery. And second, figuring out the USB docking station able to convert to USB A, SD card reader, and HDMI out.

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Discussions

Beauregard Slim wrote 04/13/2019 at 23:31 point

I don't want to discourage you in any way.  The idea is great.  This will fit very nicely in a laptop bag, unlike many of the brick-style laptop chargers. 

Having owned a few macbookpros (since the 2006 1,1 actually), my first thought is heat.   Apple laptops *will* cook themselves. 

Apple designs use the aluminum skin as a radiator.  Having something sleek and form fitting will look nicer and reduce bulk, but in my experience this is bad.  Consider leaving a gap between your battery pack and your laptop to allow air flow. 

You might even consider adding a small fan to the center of your battery pack design.  I suspect your power circuits are going to need one anyway.   

Definitely add temperature monitoring to your menu bar (and probably some fan control software) if you are going to clamp a big battery pack to the bottom, especially if you are partially blocking your rear vent with your mounting hardware. 

  Are you sure? yes | no

Harrison Freedman wrote 04/14/2019 at 15:48 point

Thank you so much for the compliment and helpful criticism. As for the blocking of airflow on the rear vent it won't really be blocked because the clips are very small and won't be blocking air flow (if you have ever owned a shell case for one of your Macs you can see just how small these clips really are). But an idea I had to actually make the laptop run cooler is run a very compact fan along the back inch and a half or so. That part of the case will have an open top so the case should be blowing cool air along the warmest part of the laptop. Once again thank you so much and if any other concerns arise please comment (the more help I can get the better, this is a huge and complicated project)

  Are you sure? yes | no

Asher Gomez wrote 04/10/2019 at 22:07 point

This looks awesome, keep up the good work.

  Are you sure? yes | no

Harrison Freedman wrote 04/10/2019 at 23:08 point

Thank you so much, i'm just finishing up soldering the battery pack and getting the charger working. I should have another update in a day or two!

  Are you sure? yes | no

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