Wingie 2 Rechargeable Battery Mod
This page documents the process I followed to modify my Wingie 2 with a built-in rechargeable battery. Anyone using this guide to attempt a similar modification does so at their own risk, and I am not responsible for any damages that could be caused as a result. Please be aware that it will certainly void any warranty on your Wingie 2, could easily and permanently damage your device, and potentially damage other equipment, property or hurt someone. LiPo batteries are notoriously dangerous, and you must be very careful when handling them. Try to source good quality batteries with some form of safety certification (for example: battery Option 1 below is UL certified, Option 2 is not).
I would highly recommend that you only attempt to do this if you are comfortable and experienced working with electronics!
- Sparkfun LiPo Charger/Booster
- Thin LiPo battery
- It must no thicker than 3.6mm
- It must have built-in protection circuitry (particularly under-charge protection, as charger does not)
- Option 1, used below: 550mAh, 35.5x62x3.2mm
- Option 2, untested: 500mAh, 34x50x3mm
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Latching push-button
- Must be latching switch type (not momentary)
- 7mm max hole diameter recommended
- Hook-up wire
- Wide Kapton tape
- Double-sided Kapton tape
- Small Phillips screwdriver
- Flush wire cutters
- Scalpel
- Soldering iron
- Desolder braid
- Small file
- Scissors
- Circuit board holder
- Multimeter
- Calipers
The basic idea is to cut the PCB trace from the USB-C connector into the 5V net of the Wingie 2 circuit, and install a battery charger/booster across the cut trace. The result is that USB power charges the battery instead of directly powering the circuit. The output of the battery, regulated to 5V, is connected to the 5V net on the circuit-side of the cut trace. A latching push-button switch disables the battery output, turning off the Wingie but allowing the battery to be charged when connected. USB data transfer is unaffected.
- Remove the white plastic caps on the slide potentiometers
- Unscrew the jam nuts on the 3.5mm MIDI / audio connectors on the top plate
- Remove the 4 Phillips screws on the top plate, 4 screws on the bottom plate, and two on the back of the case
- Remove top and bottom plates
- Separate the front half of the case
- Slide the circuit board out of the back half of the case
I recommend using a circuit board holder to hold the PCB off the work surface, and avoid putting pressure on the buttons while working on it. The buttons, with their long caps, are easily bent and can be damaged by applying pressure.
The battery and charger will sit in the gap between the back of the PCB and the back half the case. The pins of the through-hole keyboard buttons take up most of this room, so they need to be trimmed down. The pins within the green area need to be trimmed. If a battery with a different footprint is used (e.g. Option 2), additional pins might need to be trimmed.
Use flush wire cutters to trim the pins and use calipers to make sure that they are not proud of the PCB by more than 0.7mm (the height of components U7 and U8).
If wire cutters don't get the pins down to 0.7mm or less, use a small file to further file down the pins - if this is the case, be very careful with cleaning up the conductive filings that could cause shorts. It might be a good idea to mask out any ICs with tape before doing this, and then using compressed air and careful inspection to make sure no shorts have been created.
Use a strip the wide Kapton tape to insulate button pins and components. The battery and charging PCB will be mounted over this area.
Use a scalpel to cut the 5V PCB trace at this location. Don't cut too close to the via, as you need some room to solder to the USB connector side of the trace afterwards. Use a multimeter to ensure the two sides of the trace are fully isolated.
Use the scalpel to carefully scrape away the black solder mask and expose a region of copper on either side of the cut trace. These will be the solder points. (Sorry for the out-of-focus image).
Solder hookup wires to the 5V connections on either side of the cut trace, on the copper areas exposed on the previous step - one on the connector side (red wire, pre-cut) and one on the circuit side (orange wire, post-cut). Solder matching ground pair wires. The back of the USB connector shield pads is a convenient place do this.
Desolder USB and battery connectors from Sparkfun charging board to reduce height. Trim the switch lever with flush cutters, to reduce how far it sticks out. Maximum height of PCB + components should be around 4mm.
Using a file, make a small notch on the bottom end of the PCB, along the non solder-masked edge where there is no danger of breaking a trace. This will be used to route the switch wires to the front side of the PCB.
Trim the switch pins close to the body of the button, to minimize interference with other components when mounted. Solder a pair of wires to the terminals - they should be long enough to go down to the notch, then be routed along the front of the PCB all the way to the top panel where the button will be mounted.
Leave button in depressed position (terminals conducting). When button is in this position, the Wingie will be OFF. Leaving it off will prevent the Wingie from powering on after completing the next step.
Turn charger switch to OFF position.
Solder cables as shown (refer to schematic for more detail).
Be very careful when cutting the connector from the battery, making sure not to short the terminals. Cut ground first, then solder to charger PCB, then repeat with positive wire.
Note that one of the button wires shares a ground pad with the ground charging wire.
Mount battery and charging PCB onto the Kapton-insulated area using double-sided Kapton tape.
Turn charger switch back to ON position after everything is soldered.
Add a second layer of Kapton tape to insulate the battery and charger PCB from the case.
Drill a 7mm diameter hole on the top case panel. Use the logo as a guide - this places the switch perfectly to not interfere with the USB connector or internal components (chiefly the middle slide potentiometer).
Mount switch to the top panel using its jam nut. Route wires between Wingie buttons, switches and sliders making sure they don't interfere.
Replace the enclosure halves and ensure everything fits snugly. Make sure that battery is not too tightly compressed. There should be as small gap between the battery and the enclosure, as LiPo cells sometimes swell slightly over time.
Add bottom panel and replace all 10 screws. Wingie 2 is ready to resonate at the push of a button!
