Introduction: Repurposed Battery-Powered Laptop Monitor
For my first instructable, I am going to make something I've always wanted. But first, a short backstory.
My laptop for 7 years finally broke down, and I was left no choice but to buy a new one. The old laptop had already gone several minor repairs, so it dawned on me that I could take anything from it without any issues of breaking something useful.
I've always wanted a second monitor to make work easier. This presented the perfect opportunity for getting one, and satisfying the DIYer in me.
So without further ado, here are the instructions to make a battery-powered portable monitor!
NOTE: Check out the photos for more detailed instructions and notes on the build!
Step 1: The Screen: Parts, Tools, and Assembly
Parts and Sources
- Screen from old laptop (for this project, the screen's serial number is N156B6-L05)
- LCD/LED LVDR controller board from online retailer (AliExpress link)
- 12V 2A power supply with barrel jack (AliExpress link)
- Screwdrivers, precision-type for small screws.
To take the screen form the laptop, simply follow the specific instructions for your device. I followed the steps in this video. Unfortunately, no photos were taken during this step, except the final result.
Once the screen is taken out, look for its model number. This is found on the back side of the panel.
Once the serial number is found, search for a LVDR controller board that is compatible with the screen. I picked one with a VGA port and an HDMI port. All that is left to do at this point is to test whether the controller and screen work, and it did!
Note that most controllers are, by default, powered by a 12V power supply. The controller I have can be powered by anywhere from 6.0V to 15.0V as tested.
It was here that I decided to make this monitor battery-powered as well, and that's where we're doing in Step 2.
Step 2: Power Source: Parts, Tools, and Assembly
Parts and Sources
- Laptop's old battery pack (for extracting the Li-ion cells and protection board)
- Screen controller's power supply or a 3rd party protection board (Aliexpress link)
- Soldering iron, soldering lead, and flux
- Flat-head screwdriver
- Optional: a pry tool kit, to extract the Li-ion cells
Since the laptop is no longer usable, the battery pack is pretty much useless. However, the Li-ion cells could still be useful if they were still adequately charged. Also, laptop power packs are designed with a charge protection board to ensure that the batteries do not get overcharged and undercharged.
In order to retrieve these parts, all that was needed was to open the power pack up, making sure not to damage the cells or the controller board. And since the power pack itself is of no use, I simply went ahead and destroyed its casing in the process. If you have access to pry tools, please use them as they are much better to use. In my case, I used a flat-head screwdriver and a small knife to open up the power pack
Once the cells and the board were out, I tested the batteries with a multimeter. You want to save any cells that have a voltage of above 3.0V. You may still be able to use cells that read out 2.5V or more. However, cells that read less than 2.0 V are essentially dead.
From this information, all the cells are still working but need to be charged as soon as possible.
Since the nominal voltage (a.k.a. the average) of a Li-ion cell is 3.7 V, this means that 3 cells will be enough to power the monitor. This means that the power pack's controller board is perfectly suited for the task, as it is not only designed to handle 3 cells, but also has a narrow profile to fit into the case.
Step 3: The Case: Parts, Tools, and Assembly
Parts and Sources
- Acrylic panels, cut to size depending on screen dimensions. Ordered online from a local supplier, pre-cut. Dimensions to match screen (see below)
- M2 bolts (50 mm in length), with matching nuts and washers. Hardware store or online
- Plastic spacers, 3 cm. These will be cut to size later. Hardware store or online
- Rotary tool (Dremel) with appropriate drill bits and cutting tools.
- Optional: Acrylic scoring and cutting tool
All computer screens are built to standard sizes. For example, i have 15.6" screen with dimensions 34.54 cm x 19.43 cm. However, this size is only for the screen itself, and does not take into consideration the edges of the screen where the supports and other parts are. So to make sure that you cut the panels correctly (or get them pre-cut properly, as I did), you must absolutely measure the monitor's dimensions yourself. for the 15.6" monitor used here, the dimensions ended up actually being 36.0 cm x 21.0 cm.
I then ended up ordering 3mm acrylic sheets, with the following properties:
- Transparent: 1 pc 23 cm x 38 cm (for the front)
- Black: 1 pc 23 cm x 38 cm (for the back)
- Black: 2 pcs 1 cm x 38 cm (for supporting the monitor)
- Black: 2 pcs 1 cm x 21 cm (for supporting the monitor)
- Black: 2 pcs 3 cm x 38 cm (for the side panels)
- Black: 2 pcs 3 cm x 23 cm (for the side panels)
I made a small mistake and ordered 1 cm x 23 cm pieces, instead of 1 cm x 21 cm. I got around this problem by cutting the excess myself with an acrylic scoring and cutting tool, and it fit perfectly. On a side note, scoring and drilling is best done with the protective paper backing still on the panels, as to avoid unnecessary scratches and easier marking with a pen or pencil.
I then used the long support pieces (the 1 x 38 cm ones) and marked all the points 0.5 cm from an end and 0.5 cm from a side. From these marks, holes were made with the drill, starting from the smallest available drill bit I have, and progressing through the sizes until a diameter of 2.0 mm is made.
Additional holes are made for securing the controller board with additional bolts, using the same drilling technique.
One of the side panels then need to be cut so that the controller board's ports and adjustment key board can be accessed.
Finally, it's time to put everything together!
Step 4: Putting Everything Together: Screen, Board, and Case
Once everything is ready, the actual build can start.
Holes were drilled into the thin side pieces. The top and bottom pieces needed two holes, one on each end. Additional holes may be drilled later for more support.
The side pieces were slightly more complicated, as holes had to be placed to support the board and an LED indicator light. The holes were drilled symmetrically in order for the final mount to look clean and professional. Furthermore, the boards were used to place the holes properly.
The top piece and the screen are then placed onto the clear front panel. Once positioned properly, the other small pieces were positioned and attached temporarily to the front panel, and then used them as guides to drill through the front.
M2 screws are then used to secure everything together, using the plastic spacers to ensure the right fit. The spacers are cut to the right lengths to make sure that the screen is 3.0 cm thick when done.
If you would like to use the monitor now without battery power, this step is almost the end (and if so, you may skip to the Final Touches page).
A piece of thin cardboard is placed at the back of the monitor to ensure that the white backing sheet will not be damaged when the circuit boards and batteries are placed.
Finally, the boards are placed in their proper positions according to the screw positions. This secures the boards and makes it less likely that they will pry loose.
Step 5: Putting Everything Together: Batteries and Protection Board
The batteries were connected to each other with wires and solder, and then the free ends of the wires to the protection board. The protection board has points where the batteries must be connected in order to charge them properly. Click here for a circuit diagram on how to connect the batteries.
The protection circuit's charging terminals are then connected to the LVDS board's power supply to both provide the battery power to it and enable charging of the batteries.
After a charge, I tested if the concept works by switching on the monitor through battery power, and it worked. However, during the real test of using the monitor, the monitor would not turn on. Upon inspection, I saw that one was no longer charging. So I replaced the dead battery with a spare one I had lying around. Also, I double-checked the connections to the protection circuit.
Unfortunately, after a second full test, some of the batteries were still fully discharged, leading me to believe that the LVDS board was the issue. So I removed its barrel jack, mounted it straight to the protection circuit, and connected it to the LVDS board via cables to where it used to be connected. This worked wonders, as the batteries now charge properly and the LVDS board gets its power from either the batteries or the power supply.
I then made a cable with 4 wires and a 4-pin PHR connector, which matches the one on the LVDS board. This was then used to connect the positive terminal of the protection board onto the 12V terminal of the LVDS board, and similarly with the ground terminals. This allows the board to be powered by the battery, as well as charge it with a 12V power supply while powering the screen. Upon testing, this worked without a hitch.
Step 6: Testing
Since the batteries were charged before installation, I expected the screen to turn on once the soldering was complete. However, this was not the case, so I powered up the screen with the 12V power supply for a few minutes, during which the screen lit up immediately.
While waiting for the batteries to be charged a little, I connected my laptop to the screen with an HDMI cable, and it worked perfectly.
After waiting 5 minutes, I removed the charger to see if the batteries worked, and they did! I then turned off the screen, and saw that it was still being powered since the built-in on-off light is still on. I now am finding the time that the screen would stay in its standby mode before actually turning off.
I then decided to test how long the batteries will last on a full charge. Since the batteries are not new, I did not expect a long battery life. However, I was pleasantly surprised that the batteries can power the screen for about 45 minutes.
On an interesting note, I also measured the voltage across the batteries as they were discharging. I noticed that when the screen's back-light was turned on, the voltage reading went down to about 0.7 V below the reading when the back light is off. Furthermore, the protection board would turn off the power to the screen at 9.7 V across the batteries. Afterwards, the voltage shoots up to 10.4 V, turning the screen on again. This is an issue to be dealt with later, but suffice to say that for now, the batteries must be charged when the screen turns off.
All in all, this is a successful project, and should be easily replicated.
Step 7: Final Touches and Recommendations
Even though the side covers are ready to be installed, I opted not to put them on yet. This will, for the moment, make using the screen and tweaking it easier.
A few improvements have already come to mind, and would soon be part of the monitor:
- An Arduino-controlled charge indicator and charge controller. The indicator is basically an 3-color LED that is controlled by the Arduino. The charge controller is for ensuring maximum lifespan for the battery. Li-ion batteries are best charged to 10% more than the battery level before charging, i.e. if the battery is at 60%, then it should be charged up to 70% before being disconnected.
- A tripod mount, to further stabilize the monitor by attaching to a tripod.
- Holes for the LVDS keypad buttons, and the corresponding replacement buttons to change the ones on the board itself. At the moment, there is no need to use the keypad, but there may be some instances where it your be useful.
- Using more nuts to secure the bolts onto the screen's front panel and support pieces. The nuts will prevent the screws from falling off when the back panel is removed. This also means that the spacer lengths will need to be readjusted.