Polk Boom Bit Battery Replacement
The Polk Boom Bit is the first wearable Bluetooth speaker to be introduced, allowing you to make calls and listen to music all while having this little speaker clipped to your shirt. As an antenna man in Perth who is often out on a roof, inside a ceiling or driving from job to job I need to be able to have a reliable speaker I can wear on the go. Traditional headsets or an ear piece just doesn’t work which can easily get knocked out when using earmuffs or moving around a lot.
One issue with the Polk Boom Bit I ran into was that over the years, the battery life had degraded so badly that I could only get 20 minutes of standby time until the speaker would turn off. I couldn’t find any repair guide on the internet on how to replace the battery on the Boom Bit so I decided to figure out how it was put together, and document the procedure. So let’s get right into it.
Separate the board from the shell
The first thing is to identify how the circuit board and internals are attached to the case and where the battery is located.
Peel back the rubber section right at the top where the speaker vent holes begin, by prying very gently, starting at the middle. Peel back just enough to reveal the two Phillips head screws. While still holding the material back with one hand, use a precision Phillips screwdriver to undo both screws
This is all that holds the board to the case, it can now slide out. Pop open the USB connector cap and using a set of pliers grip the centre of the orange plastic section, being careful to not touch the USB connector at all or damage it. Hold the shell firmly in one hand, and with a very firm grip on the pliers to avoid slippage, pull straight out. The entire assembly should come out as one piece.
Do take care as not to damage the speaker, which can be accidentally impacted when pushing or holding the assembly during battery replacement. At this point you may like to take the opportunity to gently clean debris and dirt from the speaker if required.
What type of battery does the Polk Boom Bit use?
The battery is a 3.7v, 180mAh lithium polymer (LiPo), measuring 22 x 16.5 x 5mm.
You may not be able to find the exact dimensions for the replacement, however from the picture we can see it’s a fairly snug fit, however there may be room to go up 1 or possibly 2mm on one of the dimensions, without fouling on the shell or having enough room for the wires to remain beside the battery. I used a 602020 battery from Ecocell.
Given the Bit Boom has somewhat of a reputation of sub-par battery life when used at higher volume for continuous listening, you may consider trying to find the highest capacity battery that will fit. For other purposes such as use as a wireless phone speaker, the factory 180mAh battery suffices.
Soldering in the new battery
Gently pull the existing battery upwards, it is held onto the board by a double sided adhesive pad, be very careful not to rip the wires off the board, as they are quite a short length so caution must be taken.
Unwrap the protective tape to reveal the circuit board of the old battery, where the solder joints for the positive and negative wires are.
Fold the circuit board out of the recces that it sits in the battery, so you may access the solder joints.
De solder the existing wires from the old battery. Red is positive and black is negative, the white wire is a thermistor that some Lithium Polymer batteries have. If your new battery does not use the white wire, you can leave the white wire unconnected however be sure to tape the end as not to cause a short circuit
When soldering a lithium polymer battery, a few precautions need to be taken. As the positive and negative contacts on the new battery are very close, extreme care must be taken to not short circuit these contacts during soldering as battery damage will occur. You may place some tape over one contact while soldering the opposite contact to avoid a short circuit. Only an extremely short and soft touch with the soldering iron is required to melt the wire onto the contact. You can use a small pair of pliers to hold the wire onto the contact while you solder it. It is also important not to accidentally short out the positive or negative terminal of the wire contact at the circuit board, directly to the terminals of the battery, as this will bypass the charging protection circuitry.
For a less experienced DIY guy, this method carries a high risk of error, and an easier alternative method is to cut and solder the existing wires from the new battery to the wires that went to the old battery. A fine knife can be used to very gently cut the skin of the wire as it is the core is extremely thin and fragile
Testing and reassembly
As with most things, the reassembly is the reverse of the disassembly. First you should test if the repair has been done properly and the new battery works. Carefully plug the assembly into a USB charger and see if the charging light comes on red, and after some time proceeds to turn blue to indicate the charging cycle has completed. This confirms the charging circuit is functioning correctly and the new battery works. Power on your Boom Bit and test that all functions work, such as connecting to your phone via Bluetooth and checking that audio works.
Gently fold the new batteries board back into the battery recces, wrap the protective tape back over the battery board and re-install the adhesive pad to the bottom of the battery. Stick the new battery as central as possible inside the board and gently fold or push the wires in so they don’t foul on re-assembly into the shell. Push the circuit board back into the shell while carefully watching the speaker as it enters, and then ensuring the battery does not foul on the casing. Re-install both screws and fold back the rubber to cover them.
Your Polk Bit Boom is now ready to use.