Voltvox Go

Portable stereo TWS Bluetooth speaker.  Made it to take golfing as it has magnets at attaches to golf cart post with ease.  Has a USB-C PD bi-directional charging port at 100W, so it charges super fast and can also be used to charge your phone or other PD devices.  I use 2.5" 4 Ohm speakers from Dayton Audio as I wanted good quality sound, but you may use any other 2.5" speakers.  The charging module from AliExpress is a 4S charging module to properly power the amp.

Here are the parts I used:

• 2ea Dayton Audio DMA70-4 2-1/2" Dual Magnet Aluminum Cone Full-Range Driver 4 Ohm 
• 1ea 100W Fast Charging Power Module for 3S 4S 5S 6S Lithium Battery PD3.1 Type-C Interface Charging And Discharging Module
• 1ea 4S Lithium Battery Capacity Indicator LED Display Board Power Level Indicator For 18650 Lithium Battery DIY
• 1ea DSP Bluetooth Module 5.0 Power Amplifier 15W*2 Stereo Electronic Frequency Division TWS Pairing 2.0/1.1
• 2ea Rectangular Magnets 80 LBS Force Size 2.36" x 0.53" x 0.20" Black Epoxy Coating Rust Resistance
• 1ea Push Button Switch
• M3 Heat Inserts
• M3 Machine Screws (various lengths)
• M3 Washers (Speakers)
• M3 Nuts (Speakers)

The power amp comes with a touch pad or a knob key.  I used the touchpad version so it could be mounted on the speaker housing.  The design has a slot for it and should sit flush against it.  The amp takes between 5-26VDC and has a few ways to power it, including a 5.5x2.1 female plug, but I used the battery connector instead as this is a portable device.

The back speaker housing has a tray for a 4S1P battery made of 4ea 18650 cells spot welded together in a ladder type or zigzag arrangement.  This was done to fit in the speaker as it was assembled.  Speakers are plenty loud with this battery configuration and actually haven't tested it at its loudest yet.  That said, the amp supports up to 26v - so in theory you could add a 5S battery but wouldn't recommend anything higher than that.  The speakers I used are about 10-15 watts with 4 Ohms, which fit nicely with this amp.

I used a switch to turn off amp when not in use, but battery is available for charging or discharging even when switch is off.  I did this so I could charge other devices with the unit when not using speaker, or to simply charge speaker when not in use.   The battery capacity indicator has to be for 4S batteries for it to properly display the battery capacity.  I used hot glue to fix it to speaker housing.

The amp I used supports TWS pairing, so I made a second one and it pairs with it so I can have one speaker on one cart and the other in the second cart while playing music from a single iphone or android device.  TWS pairing was fairly straight forward. 

Printed in PETG, except bumpers which I printed in TPU.  The top bumper his held by a lip in the top cover that the bumper slides over.  It takes some force to get it in there, so I recommend you use a plastic tool to help you along.

The speaker grills are printed in ABS GF, but suspect PETG or ABS would work.  I don't recommend PLA for any of this if you want it to last.

Enjoy!!