portable bluetooth + wifi speaker build - battery management unit

Hi everyone!
Thank you for checking out this portable Bluetooth WiFi speaker I came up.
I will have the laser as usual
In the steps below, the cutting plan, the wiring diagram, and the entire list of parts and tools.
Make sure you check out my YouTube video first and then come back for more details.
Let's start!
Laser cutting plywood is necessary for this building.
Because I don't have a laser-
I did it myself and outsourced a few people from a local company who could laser cut plywood for me.
You can find the laser cutting plan below.
The scale of the drawing may be disrupted, so for reference only-
The diameter of the hole next to the Bluetooth and WiFi logo on the back panel should be 1. 8 millimeters.
These holes are for LEDs.
You should receive 5 different kinds of plywood
Two front panel, two back panel and shell template.
In addition, a plywood disc is included in the plan and you should be careful not to lose it.
For volume control potentiometer.
The same is true for round cuts near Battery signs
It will be used as a button.
Since the tweeter I use is no longer on sale, I updated the plan for the Speaker accordingly.
I also included the wiring diagram, which you can download or print, but make sure to zoom in for a better, clearer view.
Let's start building!
For this speaker, I decided to try to implement not only Bluetooth 4.
There is also a WiFi module.
Here I am using the Up2Stream WiFi module, which is very easy to use and provides excellent sound quality at a reasonable price.
There is also a secondary input that automatically disables Bluetooth or WiFi input when plugged in, let's make a simpler, cleaner speaker with fewer buttons and switches, which is always
The speakers are powered by three lithium-ion 18650 batteries in series, resulting in 12.
6 volts, about 3Ah total capacity.
The battery management system is monitoring the battery (BMS)
I'm going to go deep and show how to connect it to a cell.
After testing, I can confirm that these batteries can be about 6-
8 hours according to volume.
For the amp, I chose one of my favorite class D amps
Yamaha YDA138-E.
It provides the driver with plenty of power with rich bass and clear treble.
One of the best features of this amplifier is that when the speaker is not playing, absolutely no audible noise is projected.
I 've tried a lot of class D amps and I can really say that this one is top notch at the price point.
For the Bluetooth module, I chose KRC-86B Bluetooth 4.
0 audio receiver.
There are a lot of boards that are better than this one now, but it still does a great job, providing a hassle-free sound and immediately connecting to a streaming device.
Parts: Tools and materials: I chose the main building material for the housing is the 12mm medium fiber board.
You can also use plywood instead, skip the drawing steps and still get good results.
But for this speaker I chose the mid-fiber board as I wanted a glossy finish.
The overall width of the housing needs to be at least 70mm wide, so my aim is to crop the mid-fiber board of 6 layers 12mm, with a width of about 72mm.
I used a relatively large mid-fiber board and followed it 6 times around the template, making sure to leave a gap between each template trace so that the jigsaw blade is in pieces that don't interfere with other templates.
It is important to track the exterior and interior of the template.
Although it is not necessary to track precisely because we will adjust the lines and curves with the router later.
After the tracking was done, I took a forstner bit and drilled it through every corner of the template that was tracked out to make sure it was away from the internal lines.
In order to avoid any tearing on the other side, it is important to drill only in the middle.
Once all the corners were drilled in half, I took a drill bit and drilled all the way to the other side.
Then I flip the paper and use the forstner drill bit again to drill holes to smooth the edges around me.
The best tool for this step is to cut the puzzle of the shell parts.
Be careful not to cut into the line, we need to be as close as possible to the line, do not cross the line.
After the cut is done, we have 6 pieces left (
Or less depending on the thickness of the material)
A rough copy of the template.
The next steps will deal with the rough issues and make it more enjoyable to stay.
This step starts with placing double pieces.
Surround the double sided tape around the template to make sure it sticks to the good one.
Once the backing is removed from the tape, it will be carefully glued to the mid-fiber board we just cut out with the right force for real benefit.
It is important to paste the plywood template so that the rough edges do not appear in the area of the plywood template.
I then load a flush trim bit into the router and start routing.
A lot of annoying mid-fiber plate dust will be generated, so make sure to use the dust collection system and the dust mask.
You don't want to suck these things in!
Once the Flush trim router bits go through all the edges around, we can do it smoothly.
We now only need a router to copy the plywood template to the medium fiber board.
My router bit did slide a few times in the plywood template and took a little material here and there, so you can see that the edges are defective here and there.
This is not a concern because I will deal with this later.
Later, I did a little work. after removing the template, I have now completed 6 pieces and ready to glue.
In order to glue the medium fiber board layer together, I used Titebond III, which is a glue that is very suitable for this application because this glue is waterproof.
Of course, you can also use regular wood glue.
Here I make sure to distribute the glue evenly around each layer.
Don't be afraid to use too much glue, the excess can always be erased.
Stacking layers on top is simple, just make sure you align with each other and remove excess glue from inside and outside.
Once these layers are stacked together, I put two plates on each side of the shell and clamp it up until the glue is dry.
You can also replace the clip with some heavy objects.
Since I am going to paint the case with glossy white, I need the case to be as smooth as possible, as each dent and defect will be shown through a transparent coating.
Here I mix the same mid-fiber board sawdust with wood glue to make the filler and I will use it to fill any defects on the mid-fiber board.
Once the filler is completely dry, it's time to polish and smooth the shell.
It is not necessary to spend too much time inside the speaker, as it will not be seen later.
I use a sander to smooth the edges and curves on the housing.
Grinding blocks can also be used, but it results in good exercise rather than an effective polishing process.
Once the shell is fully polished, I use the same filler again to fill any small dots that appear.
Once the filler is polished, the shell is now very smooth.
Ready laser-
We first need to polish any burn marks left by the laser.
I use the random track Sander to quickly remove burn marks from the panel.
Of course, ordinary sandpaper can also be used.
Once the panel is smooth, I spray it between dry clear paint layers with a few layers of transparent paint to remove any burrs or bubbles.
So that we can get a smooth and smooth surface.
I then apply a thin layer of wood glue to the panel and stick it together.
You can see in the picture how the panel needs to be glued together.
It's important to make sure the panel is aligned very well, so take care of it as much as you can.
As you can see, I should apply the glue on the panel instead of the back of the front panel.
But this is not a big problem.
Once the case was completely dry with the filler and glue, I made the round egde for the case with a round drill bit.
I made a very light passage and a deeper passage on one side of the shell, removing more material on the front of the shell.
Upon completion, I removed any rough edges left by the router with some sandpaper.
I then place the back plate in the proper position and drill holes for the screws that will fix the back plate with small bits.
I also used the 20mm forstner drill bit to drill a hole on the right side of the housing of the main switch.
A groove was also drilled for the plywood disc to keep it in place.
To do this, I use a forstner drill bit of the same size as the plywood disc to go deep into the shell 3mm.
I then drilled all the way with a smaller forstner drill bit, leaving a lip around the hole to rest the disc.
The plywood disc is then glued to the appropriate position and polished with a filler applied to the edge to fill any gaps.
I then drilled four holes at the bottom of the shell for rubber feet.
It's a good idea to do this step before painting the shell, as these holes come in handy when painting.
In order to paint the shell with the chosen color, first we need to address the tricky nature of the mid-fiber board, that is, it is able to absorb a large amount of liquid, including paint that touches its surface.
In order to get a good paint finish on the medium fiber board, we need to make a thick coating or a coating that does not absorb the paint into the pores.
Since I was unable to provide simple sealing materials for the medium fiber board in my country, I chose 50-
A mixture of 50 water and Titebond III waterproof glue.
I chose Titebond III because it is used outdoors and will not be infiltrated by liquid.
I simply mixed the two together, brushed a thick coat on the mid-slim board housing, and then let it dry thoroughly at room temperature for the night.
Don't be afraid to apply a thick coat, the deeper it goes into the mid-fiber boardthe better.
I used about 200 when the sealer was completely dry-
400 sandpaper, used to polish the surface of the primer coating.
To start the painting process, I use paper towels and paint thinners to remove any oil or residue from the surface of the shell.
Once the case was clean, I sprayed several layers of gray primer.
Please note the screws at the bottom-
That's why we drilled the rubber foot mounting holes before painting.
We can now use several screws as a representation of the shell when painting.
I also fixed the case with a bolt through the potentiometer mounting hole.
After the primer coating was completely dry for the night, I wet polished the surface with 400 sandpaper and a spray bottle full of water.
I then applied a few layers of glossy white coating and once it was dry I applied a few layers of varnish.
After that, I let the shell dry for a few days until the thinner smell of the paint disappears.
In this speaker structure, I used a total of three passive radiators because the three passive radiators are twice the size of the bass horn cone.
To glue the passive radiator in place, I used epoxy glue of two ingredients and I applied it to the edge of the plywood.
I then carefully put the passive radiator in place to allow the epoxy to cure for a few hours.
Since I already have all the information about wiring in the video and wiring diagram, I will not go into details.
So I would like to provide more information about the battery pack, because the wiring of the battery pack is a mystery for most people. Build a high
We need three main parts-
Lithium ion batteries, BMS and power supplies for charging.
For lithium-ion batteries, I chose three ncr18yppf battery units with a capacity of about 2. 8Ah each.
They have been in use for quite some time, which is why they have a lower capacity.
Since our goal is that the voltage of the amplifier is about 12 volts, we will use 3 s (
Three-grid series)BMS (
Battery Management System.
The BMS board is an important part of the battery pack as it will control the charge and discharge of the battery to ensure that all batteries are balanced and free from short circuit
Circuit, overdischarge, and many other risks.
You can see the picture of the battery pack wiring diagram.
It's really simple and easy to do.
Many people are afraid to weld 18650 batteries, but according to my experience of welding these batteries,
It is safe if you do it carefully.
The point is to heat the battery as little as possible when welding-
Therefore, it will be easy to complete this work using high power soldering iron and a large amount of flux.
So to make the battery pack, I put the batteries opposite each other and glued them together with hot glue.
Then I stuck a double sided tape on each honeycomb Ant, stuck the BMS on it, make sure B-
The end is aligned with the negative end of the first cell, and the B end face is aligned to the positive end of the third cell.
The rest of the wiring can be seen in the picture above.
After the welding was done, I protected the contacts with Kapton tape for safetycircuits.
For this project, I decided to use something more professional than hot glue to install the components.
It may be a bit overdone to install the electronics, but I used brass brackets that were fixed with screws on the other side.
The components can be placed on the stand and screwed down with a hex nut so that they can stay in place well.
Once the components are in place, it looks like a mess, but almost everything is connected now!
Important: one of the main goals of this version is to make the speakers not breathable.
Therefore, it is necessary to apply glue where the air may leak. For example -
Switch around battery power indicator, Aux port, Bluetooth/WiFi switch and led.
I then glued the small plywood cut of the battery power indicator switch with a small piece of double-serving epoxy glue.
Apply some wood glue on the edge of the front panel and place the case on it.
Make sure to apply some glue to the inside of the housing that meets the front panel with your fingers to seal any gaps.
Then I put a few heavy objects on it and let it dry completely.
After the paint is completely dry, we can check the results.
As we can see, it has the highlight I want even without polishing.
In the bright light, there are still some imperfections to see, but as I mentioned in the video --
I will do the same.
To be honest, I am very happy with the results of the paint.
We can now attach the rubber foot to the lower side of the housing.
It can stand up by itself now!
It's long now.
The moment to wait for the speaker driver to be installed.
To install the tweeter, I simply applied some pva glue to the edge and pressed the tweeter in place.
Because they fit perfectly, I don't need to worry about falling off soon.
I like the way they sit flat on the panel.
Since the bass speakers have foam washers installed, I just fixed them down with bolts and nylon nuts on the other side to keep the bass speakers good.
Before installing the speaker wire to the panel, I weld the speaker wire from the amplifier to the speaker drive.
There are only a few tasks left.
For example, install the main switch in place and fix it in place with a nut from the other side of the interior.
I also install the volume potentiometer by fixing the volume potentiometer with the supplied nut and placing the potentiometer knob.
Finally, we can screw the back plate in place and we're done!
All that's left to do is charge the speakers, check the battery with the battery level indicator we connect to, we can connect now!
As I said, the speakers can be played via Bluetooth, WiFi or Aux.
In the demo, I chose to play some music via Bluetooth.
As I said before, once Aux is connected to the stereo jack, Bluetooth and WiFi disconnect without any additional switches.
The WiFi audio stream can be enabled through the app, and you can find more information here on how to connect it. I have to say -
I am very happy with the results of this speech.
I apologize for the crappy sound test on the video, but you have to trust me --
Not only does it look decent, it sounds good too!
I did have some flaws while building the speakers, but hey-
At least I learned something!
I really hope you did the same!
Thank you so much for checking this project and I hope I inspire you to build a speaker of your own.
If you're still hesitatingdo it!
This is very valuable and the knowledge you get by making it is priceless.
Not to mention the fun!
Thank you again for listening to my project and I will see you on the next one! -