Essential Tips For The Parallel Mode Of Dual DC Stabilized Power Supply
20 Nov 2025
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Parallel Mode: Expansion Solution for High-Current Output
1. Core Definition & Application Scenarios
In parallel mode, the output terminals of the two power supplies are connected in parallel, making the total output current equal to the sum of the two channels (I_total = I1 + I2). The voltage is controlled by the master channel (U_total = U1 = U2). It is suitable for scenarios requiring high current when a single channel is insufficient.
Typical application scenarios:
- High-Current Load Testing: Test an 8A-rated DC-DC converter (single channel max output 5A) by connecting two power supplies in parallel (5A + 5A = 10A) to meet the test current requirement.
- Battery Charging: Charge a large-capacity 12V lead-acid battery (requires 6A charging current) by connecting two 3A-output channels in parallel to provide 6A current, shortening charging time.
- Industrial Production Line Power Supply: Power multiple small loads (total current 7A) on an assembly line (single channel outputs 4A) by connecting two channels in parallel (4A + 4A = 8A) for stable power supply, avoiding single-channel overload.
2. Switching Operation & Wiring Standards (Key Points)
- Mode Switching: First, adjust the voltage of both channels to the same value (e.g., 12V), turn the current knobs to maximum, turn off the output switch, and press the "MODE" button to switch to "PARALLEL" mode (some power supplies display "并联"). After switching, specify the master channel (usually CH1 by default; some models allow setting via buttons). The master channel controls voltage, while the slave channel (CH2) automatically synchronizes with the master’s voltage and provides additional current.
- Correct Wiring Standards (Must Follow):
- Same-polarity parallel connection: Use thick wires to connect CH1’s "+" terminal to CH2’s "+" terminal, and CH1’s "-" terminal to CH2’s "-" terminal. The wire must match the total current requirement (e.g., 2.5mm² copper wire for 10A total current).
- Load connection: Connect the load’s positive terminal to the junction of the two "+" terminals, and the load’s negative terminal to the junction of the two "-" terminals, ensuring current is shared by both power supplies.
- Current-sharing resistor setup: For power supplies without automatic current-sharing, connect a small-value current-sharing resistor (usually 0.1Ω/5W) in series with each channel’s output to avoid circulation (caused by slight voltage differences between channels, which increases power loss or even damages equipment). Power supplies with automatic current-sharing (e.g., KUAIQU R-SPS series) can omit the resistor, as the internal system automatically adjusts current distribution with ≤5% current-sharing error.
- Forbidden Wrong Wiring: Do not use parallel wiring directly in series mode. Ensure the two channels have identical voltage before parallel connection—otherwise, the higher-voltage power supply will discharge to the lower-voltage one, generating large current and burning equipment.
3. Precautions & Stability Assurance
- Power Supply Specification Matching: Prioritize parallel connection of power supplies of the same model and production batch to ensure consistent voltage adjustment characteristics and internal resistance, avoiding current-sharing imbalance. For different models, test voltage consistency (error ≤ 0.1V) first, and ensure total current ≤ 80% of the sum of the two channels’ rated currents to leave a safety margin.
- Master-Slave Coordination Control: In parallel mode, only adjust the master channel’s voltage (the slave channel synchronizes automatically). Do not adjust the slave channel’s voltage independently, as this will trigger current-sharing protection. If the master channel fails, the slave channel stops output automatically to avoid insufficient load current from single-channel power supply.
- Heat Dissipation & Overload Protection: Parallel connection increases total power and heat generation. Ensure good ventilation (normal fan operation, no obstructions around) and avoid long-term full-load operation (recommended continuous current ≤ 70% of total rated current). Enable overcurrent protection and set the threshold to 1.2x the total rated current to prevent power supply damage from load short circuits.
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