On this page
A phone that will not charge from a van battery at dusk is the moment when buck converter vs dc to dc converter stops being a parts-bin question and starts being a wiring question. A buck converter is a step-down DC-DC converter, the kind that takes a higher battery voltage and hands a lower voltage to a small load. A DC-DC converter is the wider family, and it includes the isolated converter built for a spare battery. This guide compares the converters from the listings: step-down modules made for USB loads, and an isolated converter made for a dual-battery setup, so the choice comes down to what the load needs.
SolarKitHQ earns a commission when you buy through links on this page, at no extra cost to you. As an Amazon Associate I earn from qualifying purchases. Affiliate disclosure.
The quick answer
A buck converter steps voltage down and nothing else: the modules below take a 12V or 24V battery and give 5V to a USB load. A DC-DC converter is the wider family, and it covers step-down, step-up and isolated conversion, so the Victron Orion-Tr below sits on the DC-DC side as a 12/24V, 5A, 120W isolated converter for dual-battery systems. Pick a buck module when the load is a phone, a Raspberry Pi 4 or another small device that needs 5V. Pick an isolated DC-DC converter when the job is feeding a spare battery at system voltage. The buck converter guide covers the step-down side in more depth.
The gear: 4 converters compared
The 4 converters below are listed by stated output power, then by warranty and protection where the output matches. The Victron Orion-Tr leads on output power and warranty, the Klnuoxj module leads the USB modules on output current, and the PlusRoc and Acridine modules state the same output voltage and current.
| Converter | Input | Output | Protection | Warranty |
|---|---|---|---|---|
| Victron Orion-Tr | 12/24V | 5A, 120W | IP43, isolated | 5 Years |
| Klnuoxj USB-C module | 8V-32V | 5V, 5A, 25W | IP68, overload, over-current, overheat, low voltage | Not stated |
| PlusRoc USB-C converter | 8-32V | 5V, 3A | Overload, over-current, overheat, low voltage | 1 Year |
| Acridine USB converter | 10-32V | 5V, 3A, 15W | Reverse connection, overload, overcurrent, overheat, low voltage, short circuit | Not stated |
The Victron Orion-Tr is the only converter here built for a battery system rather than a USB load. The maker lists it as a 12/24V, 5A, 120W isolated converter with IP43 protection and screw terminals, and states a 5-year warranty. It suits a dual-battery setup where one battery feeds another at system voltage. It does not suit a phone or a Raspberry Pi 4, since the listing states no 5V USB output.
The Klnuoxj module has the highest stated output current among the USB modules: 5V at 5A and 25W through a USB-C port, from an 8V-32V input. The maker lists IP68 protection plus overload, over-current, overheat and low-voltage protection, and names the Raspberry Pi 4 and cell phones as uses. The maker also warns to observe polarity, since a reverse connection may damage the unit. No warranty term is stated.
The PlusRoc converter gives 5V at 3A through a USB-C port, from an 8-32V input, and the maker lists efficiency up to 96%. The maker lists 20 AWG power leads, a sealed enclosure, overload, over-current, overheat and low-voltage protection, and a 1-year warranty. The maker lists it for the Raspberry Pi 4, cell phones and other devices that need 5V at 3A, and lists its weight as 0.09 pounds.
The Acridine converter gives 5V at 3A and 15W through a USB Female port, from a 10-32V input, with a 96% conversion rate and a 13.77-inch USB cable. The maker lists input reverse-connection protection plus overload, overcurrent, overheat, low-voltage and short-circuit protection, and names GPS navigation, car recorders, car radios and car audio among its uses. No warranty term is stated.
How to choose the best buck converter vs dc to dc converter
Match the converter to the battery on one side and the load on the other, then check protection and warranty.
Match the input to the battery
All 4 converters accept 12V and 24V sources: the PlusRoc and Klnuoxj modules state an 8V to 32V range, the Acridine states 10V to 32V, and the Victron is listed for 12/24V systems. Check that the source voltage sits inside the stated range before ordering, and note that the Klnuoxj module warns a reverse connection may damage the unit, so polarity matters at the input. See the step-up vs step-down comparison for how the two directions differ.
Match the output to the load
A phone, a Raspberry Pi 4 or another small device that needs 5V takes a buck module: the Klnuoxj states 5A and 25W, while the PlusRoc and Acridine state 3A, with the Acridine also stating 15W. A spare battery takes the Victron, which states 5A and 120W at system voltage with no 5V USB output. The best 12V USB-C chargers cover the same 5V use in a plug-in form.
Check protection, enclosure and warranty
The Klnuoxj module states IP68 protection, the Victron states IP43 protection, and the PlusRoc states a sealed enclosure; the Acridine states no IP code. The 3 USB modules list overload and overheat protection, and only the Acridine lists reverse-connection protection. The Victron states a 5-year warranty and the PlusRoc states a 1-year warranty, while the Klnuoxj and Acridine state no warranty term. A longer stated warranty and a stated IP code are worth more than a bare claim of toughness.
FAQ: power away from the grid
Is a buck converter the same as a DC to DC converter?
No. A buck converter is one kind of DC-DC converter: it steps voltage down, and the 3 modules here step 12V or 24V down to 5V. The wider DC-DC family also covers other conversions, and the Victron Orion-Tr is listed as a 12/24V, 5A, 120W isolated converter for dual-battery systems.
What size buck converter do I need for a Raspberry Pi 4?
The PlusRoc and Klnuoxj modules name the Raspberry Pi 4 as a use. The PlusRoc states 5V at 3A through a USB-C port, and the Klnuoxj states 5V at 5A and 25W through a USB-C port. Pick the stated current that matches the load, and check the input range against the battery: 8-32V for the PlusRoc and 8V-32V for the Klnuoxj.
Can these converters run in wet conditions?
The Klnuoxj module states IP68 protection, and the Victron states IP43 splash-resistant protection when installed correctly. The PlusRoc states a sealed enclosure, while the Acridine states no IP code, so its listing gives no guidance on wet use.
Which converter has the longest stated warranty?
The Victron Orion-Tr states a 5-year warranty, the longest stated term here. The PlusRoc states a 1-year warranty, and the Klnuoxj and Acridine state no warranty term.
Related solar guides
See every DC to DC charger guide and all controller and inverter guides, plus what battery charger to choose and how to select a solar charge controller.
