Hi All,

2 Months back I had custom built a portable multimedia speaker for my friend. It had everything that he needed, MP3/ FM / USB/ SD card/ Aux in / IR remote and external bluetooth

It had few issues

AC powers connection,not 100% portable
External Bluetooth needed power source
Lithium Ion batteries are expensive

In this instructable, I will share how I fixed these problems

Features of the final built

True Portable
Lightweight
6W / 80DB output
Mp3/FM/USB/SD/ Aux
IR Remote
External Bluetooth
6000 mAH battery / 6 to 7 hrs of life with bluetooth
Battery charging LED indicator
5V USB output, can be used for mobile charging too

Step 1: What Do We Need ?

Material

Portable Multimedia speakers
Ols laptop battery
TP4056 with battery protection
3.7 to 5 V DC Step up convertor with USB
Switch

Tools

Dremel
Wood Saw
Wires
Soldering iron
Hot glue gun
Black OIl paint and brush

Step 2: Extract Lithium Ion Batteries

We all have at least a laptop at home for years and know that the laptop batteries do not last over 2 to 3 years. I had a bad laptop battery, which I have used for the build

Using Screwdrivers, break open the outer case
Extract batteries and separate them from any connections or circuit
Test individually for voltages ( between 2.5 to 3.7V can be reused)

Put these batteries for charging using TP4056 and measure voltage (open circuit ) should be around 4.2 V.

Few batteries will not detect or charge, You should discard the faulty ones with proper care and as per guidance / regulation followed in your country

Warning: Always use TP4056 or good charger because cheap chargers may over charge your batteries, which could lead to battery explosion

Step 3: Preparing Battery Pack

The Batteries I extracted were of LG 3000mAH. I connected two of these in parallel and left it for 4 to 5 hours

Even though the batteries were fully charged, they can carry slide variations in voltage. Leaving them connected for few hours balances them.

Donot not overheat the batteries while charging.....

I am using Electrical tape to hold them together and for covering metal connectors

Step 4: Back Panel

Since my speakers ran on AC power, it had holes supporting the cables etc. I needed to replace it with a new panel, with holes for

Bass tube
A switch
USB out
Micro USB charge
LED Indicator

LED Indicator : I used a transparent PVC / plastic stirrer, which my son likes to collect. I fixed a about 1 inch piece over TP4056 so that it can refract light from LEDs on TP4056