GreatScott! DIY LiPo Supercharger Kit
Assembly Manual
Introduction
This DIY LiPo Supercharger, developed by GreatScott! and produced by Elektor, is designed to charge a single-cell LiPo battery while protecting it against overvoltage, overload, and short-circuits. It also features the ability to boost the battery voltage to either 5 V or 12 V. The boosted output voltage is protected by an 'eFuse' IC, providing a maximum output of 1.52 A at 5 V or 0.76 A at 12 V. The charger requires a +5 V power supply, which can be connected via USB-C or directly to pads on the PCB. Additional connections can be made via pads or single pinheaders.
Specifications
| Feature | Value |
|---|---|
| Input Voltage | +5 V / 2 A max. |
| LiPo Protection (XB8089D) | Overcharge Detection: 4.250 V, Overcharge Release: 4.10 V, Overdischarge Detection: 2.50 V, Overdischarge Release: 3 V, Overcurrent Detection: 10.0 A |
| Output Voltage | 5 V / 1.52 A, 12 V / 0.76 A |
| Thermal Shutdown | Auto-retry |
| Enable/Undervoltage Lockout | Rising: 1.2 V (typ.), Falling: 1.1 V (typ) |
How it Works
The circuit is divided into three main blocks:
- Protection: IC2 (XB8089D) provides advanced lithium-ion/polymer battery protection, including power MOSFET, high-accuracy voltage detection, and delay circuits. It also protects against reverse battery connection.
- Charger: IC3 (BQ24092DGQR) is a 1A, single-cell Li-Ion and Li-Pol battery charger with safety features like JEITA Temperature Standard, Over-Voltage Protection, Input Voltage Dynamic Power Management, Safety Timers, OUT Short-Circuit Protection, and ISET Short Detection. The ISET pin programs the fast-charge current, set here by resistor R6 to approximately 1 A. R7 sets the Current Termination Threshold and Pre-Charge Current. LED1 indicates input voltage status, and LED2 indicates charging status.
- Power Supply: This part uses a Step-Up DC-DC Converter (TPS61085DGKR, IC1) and an 'eFuse' (TPS259621, IC4). The output voltage is selectable between 5 V and 12 V via switch S1A, which adjusts the voltage divider (R1||R2, R3 for 5V; R2, R3 for 12V). An eFuse protects against short circuits, overloads, and undervoltage. The output current limit is set by S1B using resistors R12 and R13 (1.52 A for 5V, 0.76 A for 12V).
The +5 V input can be supplied via a USB-C power adapter (Elektor Store no. 191200) or by connecting wires to the +5 V and GND pads. The battery connects to the BAT+ and BAT- pads, and the output is available at the OUT and GND pads.
Tips & Tricks on SMD
SMD Resistors
SMD resistors are marked with 3 or 4 digits. For 3 digits, the first two are the value, and the third is the multiplier (e.g., '103' = 10 x 10³ Ω = 10 kΩ). For 4 digits, the first three are the value, and the fourth is the multiplier (e.g., '8452' = 845 x 10² Ω = 84.5 kΩ).
SMD Capacitors
Ceramic capacitors often lack printed values. Distinguishing features include dielectric material color: NP0/C0G (1 pF to 1 nF) is typically white/light grey, X7R (1 nF to 1 µF) is light brown, and X5R (>1 µF) is dark brown. Values can overlap, and colors may vary by manufacturer. Electrolytic SMD capacitors are often chip-type with a square black bottom and chamfered corners at the positive connection. Values are in microfarads (µF), e.g., '330' means 330 µF. Capacitance ranges are typical for 50-V rated capacitors and may overlap.
SMD LEDs
The cathode of an LED is usually marked by a small dot on the top side, or a triangle-like diode symbol on the bottom.
SMD ICs
SOIC and TSSOP packages typically have a small round indentation or notch to indicate pin 1. Some manufacturers also add a chamfer on the side of the package at the row of pins where pin 1 is located.
Soldering SMD Parts
When soldering 1206-style resistors and capacitors, solder one side while holding the component with tweezers, then solder the other side. Avoid moving the component as the solder joint cools to ensure a good electrical and mechanical connection. A soldering iron with a fine tip is recommended. Use thin solder (0.5 mm or 0.35 mm diameter). Larger diameter solder (0.8 mm) can lead to excessive solder and short-circuits. Thoroughly check the PCB during and after soldering.
Assembly Manual
Tools and Materials Required:
- Solder Iron: A solder iron or station with a fine-tip is recommended for working with small SMD components. A larger tip may be beneficial for components requiring significant heat absorption.
- Tweezers: Essential for positioning and securing SMD components during soldering. A magnifying glass or microscope can aid in identifying small components.
- Solder Wire: 0.8-mm diameter solder wire is recommended for convenience with small SMD components.
- Electrical Tape: Useful for holding the PCB in place during soldering.
Steps:
- Prepare Soldering Iron: Heat your soldering iron to approximately 360 degrees Celsius for most SMD connections. For joints requiring more heat due to copper mass (GND layer), you can increase the temperature to 400 degrees Celsius.
- Solder Resistors: Secure the PCB with electrical tape. Solder the SMD resistors, ensuring they are placed in the correct locations according to the PCB markings. Refer to the GreatScott! video for soldering techniques.
- Solder Capacitors, LEDs, and Diodes: Following the same method as for resistors, solder the capacitors, LEDs, and diodes onto the PCB.
- Solder Remaining Components: Attach the remaining components, including the USB Type-C port, large capacitor, inductor, and switches. The PCB assembly is now nearly complete.
- Connect Battery: Connect your LiPo battery to the BAT+ and BAT- pins to begin charging.
- Test Output Voltage: Turn on the output of the Boost Converter and verify the presence of 5 V and 12 V on the output terminals.
Bill of Materials
Resistors
- R1 = 84.5 kΩ, 1 %, 0.25 W, SMD 1206
- R2 = 158 kΩ, 1 %, 0.25 W, SMD 1206
- R3 = 18 kΩ, 1 %, 0.25 W, SMD 1206
- R4 = 13 kΩ, 1 %, 0.25 W, SMD 1206
- R5, R7 = 1 kΩ, 1 %, 0.25 W, SMD 1206
- R6 = 536 Ω, 1%, 0.25 W, SMD 1206
- R8, R9 = 1.5 kΩ, 1 %, 0.25 W, SMD 1206
- R10 = 10 kΩ, 1 %, 0.25 W, SMD 1206
- R11 = 100 kΩ, 1 %, 0.25 W, SMD 1206
- R12, R13 = 1.2 kΩ, 1 %, 0.25 W, SMD 1206
- R14 = 4.7 kΩ, 1 %, 0.25 W, SMD 1206
- R15 = 1.8 kΩ, 1 %, 0.25 W, SMD 1206
Capacitors
- C1 = 3.3 nF, 5 %, 50 V, NPO, SMD 1206
- C2, C7, C11 = 100 nF, 5 %, 50 V, C0G, SMD 1206
- C3, C4, C6, C8, C9 = 10 µF, 10 %, 25 V, X7R, SMD 1206
- C5 = 1 µF, 10 %, 50 V, X7R, SMD 1206
- C10 = 10 nF, 5 %, 50 V, X7R, SMD 1206
- C12 = 470 nF, 10 %, 50 V, X7R, SMD 1206
- C13 = 330 µF, 20 %, 35 V, SMD 10.3x10.3
Inductors
- L1 = SCDS74T = 3.3 µH, 20 %, 3.5 A, 35 mΩ, SMD size 7.3x7.3x4.5mm
Semiconductors
- D1, D2 = SL22-E3/52T, SMD SMB
- LED1 = 11-21/GPC-AM2P1/2T, LED, green, SMD 1206
- LED2, LED3 = 15-21SDRC/S530-A2/TR8, LED, red, SMD 1206
- IC1 = TPS61085DGKR, SMD VSSOP-8
- IC2 = XB8089D, SMD SOIC-8-EP
- IC3 = BQ24092DGQR, SMD MSOP-10-EP
- IC4 = TPS259621DDAR, SMD SO-PowerPad-8
Miscellaneous
- S1 = switch, DPDT, THT, 9.1x3.5 mm (K2-2235D-F1)
- S2 = switch, SPDT, 250 VAC, 3 A (XKB, SS-12D06L5)
- K1 = USB-C BoB, Elektor Store no. 191200
Optional
- PC1-PC6 = pinheader pin, 1x1 (BAT+/BAT-; +5V/GND; OUT/GND)
- PCB 191188-1 v2.1
