Can You Parallel Two CHEAP DC-DC Chargers For Double Output?

Summary

The video tests whether two budget 25A DC-DC chargers can effectively replace one premium 50A unit. It compares two Adventure Kings chargers connected in parallel with a Victron Orion XS 50A, charging a lithium battery bank from 50% to full.

Test setup and findings

The chargers were tested with matched battery starting conditions and the same input voltage. The presenter monitored output, power and temperature, and set both systems to a 14.5V lithium charging profile.

• Charging time: The Victron averaged about 665W and finished in roughly 1 hour 7 minutes. The two Kings chargers averaged about 586W and took roughly 1 hour 24 minutes.
• Output power: Peak output was approximately 690W for the Victron and 640W combined for the Kings chargers. Although each Kings charger is rated at 25A, its output is limited to around 300W—about 21A at 14.5V. The Victron’s roughly 700W capacity allows it to deliver about 48A at that voltage.
• Heat: Both setups reached broadly similar peak temperatures, around 45–46°C on their hot sides. Producing less power at similar temperatures suggests the paired budget units waste more energy as heat.
• Input-voltage drop: Under heavy load, the AGM input bank’s voltage fell from about 14.2V to 13.3V for around 15 minutes, reducing both setups’ power output. The presenter emphasizes the importance of correctly sized cables and sound connections.

Practical trade-offs

Two budget chargers can cost less and provide redundancy: if one fails, the other can continue charging at 25A. They can also be operated individually to reduce the charging load. However, paralleling them adds wiring, fuses and connections, creating more potential failure points and opportunities for voltage drop. Adding a second charger to wiring designed for only one could cause substantial voltage drop or damage.

The Victron is smaller than the two budget chargers combined and offers app-based monitoring and adjustable output current. It performed better in this test, though it costs more. It does not include a solar controller. The Kings units include MPPT solar control, but the presenter notes that they cannot charge from solar and the vehicle alternator simultaneously. A separate MPPT controller is suggested when combining solar and alternator charging.

The charging-time difference was modest at the tested capacity, but the presenter notes that it can become more significant with larger battery banks. Overall, paralleling two chargers can work, particularly in a new system built with suitable wiring. A single premium unit is simpler, more efficient and easier to monitor.

Review and guide points

The video demonstrates a bench comparison of two 25A chargers against one 50A charger. It explains why rated amps do not necessarily equal charging current at higher battery voltages and covers wiring, fusing, voltage drop, redundancy, output control and solar-charging considerations.

The test uses short cables and a carefully controlled setup, so the presenter cautions that real installations may experience greater voltage drop.

Main speaker and source: Cahn, the channel host, presenting his test and analysis of Adventure Kings 25A DC-DC chargers and the Victron Orion XS 50A.