Fix/Change Battery for an Old Bluetooth Speaker

I had an old Bluetooth speaker lying around, which did not last long on a charge. Clearly a Battery issue, so as part of the Fix it Challenge I went on about to give it a new life. This basic approach can be applied to not just a Speaker but any old electronic device which has a rechargeable battery and is showing signs of degraded battery.

1. Solder Iron
2. Solder
3. Screwdrivers
4. Wire Strippers
5. Old Bluetooth Speaker / any Rechargeable electronic device
6. Multimeter
7. Replacement Battery (18650 or any single cell lipo battery )
8. Hex Saw ( Optional )
9. Caliper ( Optional )

Look for Screw holes, in absence of Screw holes like in my case pry open the grill to reveal Screw holes. Use a screwdriver to open all screws ( keep them in a safe place ).

Disconnect and discard the old lipo battery carefully. ( properly dispose off Lipo Batteries as they are an explosion risk )

Cut the wires connecting the battery.

Usually the wires are color coded, Red --> Positive, Black --> Negative.

Double check using multimeter on (Volt) configuration to identify which is positive and negative polarity of the battery and its corresponding feed wire to the circuit.

In my case the terminals were highlighted with a +/- sign on the connector.

Identify the positive and negative terminals of the replacement lipo battery using a multimeter.

I am using a 18650 lipo battery salvaged from an old powerbank. Ensure that the voltage of the cell is more than 3.7V, its just a basic check to ensure the battery is in good condition. Solder the positive and negative feed wires to the battery directly ( we will not be changing the batteries frequently as we would be charging them directly with original circuit) .

In my scenario, the battery was significantly bigger than the original one, I choose this because it will give me higher runtime for the device ( caveats being slower recharge time ). And the back casing did not fit the battery properly. There was a slight bulge from adding the bigger battery. Originally, I thought to 3D print a back enclosure however the problem was that there are connections for charging/Aux/SD Card on the top which if extended would become unusable.

So I marked the back case using a digital Caliper, ( you can use any straight edge to mark ) and using a hex saw cut the marked area for the battery.

Put the back cover and check your connections by switching on the device, Once you are satisfied with its working, put the screws back in their place, and put the grill back on. Congratulations! You just gave another life to your old discarded device.