DFR0682 LattePanda Sigma UPS Wiki - DFRobot

Introduction

The LattePanda Sigma UPS is a UPS expansion board specifically designed for the LattePanda Sigma. It utilizes 4 x 18650 lithium-ion batteries as the power storage solution and supports external power supply via Type-C PD and a 5.5mm DC interface. In the event of a power outage, the four 18650 batteries can directly power the LattePanda Sigma without the need for additional boost or buck conversion steps, thus minimizing energy loss, with a battery life of up to 8 hours[^1].

With the HID-UPS protocol, the LattePanda Sigma UPS can be recognized by the operating system as a battery device, enabling automatic power management features such as entering sleep mode and automatic shutdown, similar to the built-in batteries of laptops. The HID-UPS protocol is implemented in Arduino and is fully open-source. Users can set a charging voltage limit to extend battery life or edit custom algorithms for more precise battery balancing.

[^1]: The data was obtained from testing with 4 x 3.7V 3400mA-h 18650 Li-ion batteries and LattePanda Sigma.

Precautions

• 💡 To ensure the UPS operates normally, please use a reputable brand of 3.7V 18650 lithium-ion battery with a capacity of at least 3000mA·h and a maximum discharge current of over 5A.
• 🔌 Batteries of the same model and similar charge levels should be installed. A significant difference in capacity among the 4 batteries will reduce the actual usable total capacity of the UPS.
• 🔋 The LattePanda Sigma UPS has integrated battery protection, allowing safe use of "flat-top" 18650 batteries, eliminating the need for "button-top" 18650 batteries with integrated protection circuits.
• ⚠ The LattePanda Sigma UPS does not support 3.2V lithium iron phosphate batteries (which are also 18650 size). Installing these incorrect batteries may cause fire or explosion during charging.
• 💤 If the UPS will not be used for an extended period, please remove the batteries to prevent over-discharge and damage.

Technical Specifications

• Power supply interface:
  • USB Type-C PD protocol
    • Voltage requirement: 15V
    • Power requirement: 100W
  • DC Jack 5.5x2.1mm
    • Voltage requirement: 19~24V
    • Power requirement: ≥90W
• Battery type: 3.7V 18650 lithium-ion battery
• Charging current: 2A
• Compatible LattePanda Models: LattePanda Sigma
• Operating temperature: 0~60℃

Hardware Introduction

User Instructions

Preparation

• Hardware
  • 1x LattePanda Sigma UPS
  • 4x 18650 3.7V lithium-ion batteries
  • 1x LattePanda Sigma
  • 1x LattePanda Sigma UPS Power Cable
  • 1x LattePanda Sigma UPS Signal Cable
• Software
  • Arduino IDE
  • HIDPowerDevice Library
  • LPUPS Library

Arduino Library Installation Tutorial

Hardware Installation

0. Turn off the UPS power switch

1. Remove the protective film from the heatsink and attach the heatsink on the MOSFET.

2. Install the 18650 lithium battery into the UPS, pay attention to the positive and negative direction.
   

3. Mounting the UPS to the Sigma Metal Base Plate with Copper Posts
   

4. Installing LattePanda Simga on top of the UPS
   

5. Connecting the power and signal cables
   
   

6. After checking that everything is in place, plug in the power supply and turn on the power switch.
   

After installing the UPS, please use the USB-C or DC 5.5x2.1mm connector on the UPS to power the LattePanda. Powering the LattePanda through its own interface will prevent you from using the UPS feature.

Software Installation

1. Please make sure you have already installed the Arduino IDE, HIDPowerDevice library, and LPUPS library.

2. Launch the Arduino IDE, open the UPS program: "File -> Examples -> DFRobot_LPUPS -> fourBatteriesLPUPS"

3. Select the corresponding development board model: "Tools -> Board -> Arduino Leonardo"

4. Select the corresponding development board port: "Tools -> Port -> COM*" (Select the port marked with Arduino Leonardo)

5. Upload the example program, and after a short wait, you can see that the battery has been recognized in the system. If you need to further set the threshold battery level for automatic power-saving and forced sleep on your LattePanda Sigma, you can adjust it in the Windows Advanced power Settings.

Adjusting Charge Limit

Keeping lithium batteries at a full charge of 4.2V for extended periods can lead to rapid wear due to high self-discharge currents. If high battery capacity is not a priority, you can set a maximum charging voltage in the Arduino program to extend battery life.

1. Launch the Arduino IDE and open “File -> Examples -> DFRobot_LPUPS -> fourBatteriesLPUPS.”
2. Locate the following section of code:

  // maxChargeVoltage = 15600;
  // LPUPS.setMaxChargeVoltage(maxChargeVoltage);

3. Uncomment the code, and modify maxChargeVoltage to your desired value.
   maxChargeVoltage is measured in mV; for example, if you set it to 15600, it means the maximum charging voltage is 15.6V, and the voltage of a single cell is 15.6V÷4=3.9V.

4. Re-upload the Arduino program. Charging will automatically stop when the total voltage of the battery pack reaches 15.6V to extend the battery life.

The allowable range of maxChargeVoltage is 14800 ~ 16800, any setting beyond the range will not take effect.

FAQ

• Q: If both the 5.5x2.1mm DC and USB TypeC power supplies are connected to the UPS, which power source will the system prioritize?
  A: The system will prioritize the power source with the higher voltage. The USB Type-C PD will automatically negotiate to supply 20V, while the voltage through the 5.5x2.1mm DC port will depend on the specifications of the power adapter used.

• Q: Can power generation devices such as solar panels or wind turbines be directly connected to the UPS?
  A: In theory, as long as the input voltage is within the range of 12~24V, the UPS can work, but we do not recommend directly connecting solar panels in this way. An overly unstable power source can cause the battery to frequently switch between charging and discharging, which may severely affect battery life. If you want to connect a solar panel, a power management module with voltage stabilization and energy storage functions, such as SKU:DFR0580, should be connected before input to the UPS.

• Q: What happens if the power adapter provides insufficient power?
  A: Insufficient adapter power will cause slow charging, inability to charge, or even battery depletion despite being connected to a power source. Please pair the UPS with a power adapter of at least 90W. It is recommended to use the 90W power supply included in the LattePanda package.

More Documents

🛒Get LattePanda Sigma UPS from DFRobot Store or DFRobot Distributor.