Seloky 12V-36V DC Voltage Protection Module Digital Low Voltage Protector Disconnect Switch (Pack of 2)
Quick take
This relay-based low-voltage protection module monitors DC input from 12V to 36V and disconnects output when your battery drops to a preset cutoff, then reconnects after the difference window. It is a practical fit for DIY battery protection in devices like portable power setups, but the current limits are tighter than the headline max, and the setup logic may feel confusing until you calibrate.
Pros and cons
Pros
- Digital cutoff control for low-voltage disconnect, with a configurable reconnect “difference” window.
- Adjustable restart delay after a disconnect, useful for preventing rapid cycling.
- Supports multiple battery chemistries (lead-acid, lithium-ion, and solar panel battery setups) for basic protection use.
- Retains user settings after unexpected power loss.
Cons
- Relay-based switching is limited for higher loads, with guidance to keep real use under 8A (and even lower considerations depending on voltage).
- Setup and calibration can be challenging, and some buyers needed to tune settings to match their system.
- It does not function as a “full power cut-off switch,” so you still need to manage power after the relay opens.
What buyers think
Buyer-review evidence is mixed on reliability and setup effort, but several clear themes show up. Many users report the protection behavior works as intended, including at least a few cases where calibration was straightforward and then the readings matched closely enough for their use. Setup can be confusing at first, with some buyers spending time interpreting the on-screen values and relay logic, especially around when the module allows output and when it blocks it. Reliability appears to be generally positive for some long-term users, but other buyers describe “hit or miss” behavior when purchasing multiple units, including cases where a unit did not turn on.
How it helps protect a DC battery system
The core job of this module is preventing your battery from discharging too far. It does this by monitoring DC voltage and using a relay to switch the output on and off. When the measured voltage hits your cutoff threshold, it stops providing power output. When the voltage rises enough to clear the reconnect window, it enables output again.
Key features that matter for real-world use
Low-voltage cutoff and reconnect “difference” window
You can set the disconnect voltage and the reconnect voltage difference. The default protection value is 12V, with a 2V difference, which means the relay disconnects around the cutoff level and reconnects after the voltage recovers by the set amount. This is important because battery systems often dip under load and bounce back when charging or when the load changes, so the difference window helps reduce unnecessary toggling.
Configurable restart delay
The module supports a delay (0 to 999 seconds) after it disconnects before allowing output again. If your system experiences short interruptions or unstable voltage recovery, this delay can help prevent rapid relay chatter.
Digital display and calibration
A screen shows status and settings during configuration. Some buyers have noted they needed calibration, and in those cases they found it manageable. If your projects depend on precise cutoff points, plan a little extra time to confirm the displayed values against your battery or charger readings.
Battery compatibility and what it does not do
It is meant for basic battery protection with lead-acid, lithium-ion, and solar panel battery setups. The relay acts as a switch, and it does not alter voltage. It also is not intended for battery packs (so if you are working with a series pack or a prebuilt pack, confirm that your voltage range and wiring approach match what the module is designed for).
Specs and limitations you should know before buying
- Input voltage range: DC 12V to 36V.
- Switching approach: relay-based output switching.
- Power consumption: under 1.5W.
- Accuracy: ±0.1V.
- Maximum current before breaker trips: 20A (but see real-use note below).
- Real-world current guidance: due to the miniaturized relay and thin PCB traces, actual use current should not exceed 8A to prevent damage to relay contacts. Guidance also notes a lower tolerance depending on voltage (example guidance mentions up to 10A when voltage is below 12V, and less than 8A when voltage exceeds 12V).
- Dimensions: 57 x 42 x 19 mm.
Setup, operation, and a key wiring caveat
The module is operated through two buttons. Settings are retained after unexpected power loss, which is convenient if your battery system power cycles.
Important caveat: the relay disconnects output, but the module still continues to draw power after it disconnects. That means you should ensure you turn off the power supply to the module when you want it fully idle, otherwise it can keep consuming battery power down to very low levels.
Who it’s best for
- DIY builders who want an adjustable low-voltage disconnect for a 12V to 36V DC project.
- Portable electronics and off-grid power setups where you want a configurable cutoff with a reconnect hysteresis/difference window.
- Projects that need a restart delay to avoid immediate re-energizing after a dip.
Who should avoid it
- High-load applications where you need to switch beyond the relay’s practical current guidance. If your load is near the limit, look for a controller designed for higher continuous switching currents.
- Users who need a true “killswitch” behavior where the controller fully stops drawing power by itself after disconnecting. This unit requires external power-off to fully stop consumption.
- Battery pack users who need protection for a pack configuration. The module’s intended scope is not battery packs, so verify compatibility before buying.
Value and buying verdict
This is a solid choice if you want adjustable low-voltage protection using a digital cutoff and a reconnect window, plus a configurable delay. The biggest tradeoffs are the relay-based switching limits and the fact that configuration can be confusing until you understand the logic, and calibration may be necessary for some systems. If you are building a small portable battery-powered device and you can keep the load current within the practical limits, the pack-of-two format makes it easier to dedicate one module to a second project or spare setup.
Alternatives to consider
If your main priority is higher current handling, you may prefer a different low-voltage disconnect/controller designed for your load rating. If you need a tighter integration with battery management (for example, for a full battery pack), look for a dedicated battery management solution intended for packs rather than a relay switching module. If you only need a simple undervoltage cutoff and you do not care about delay and hysteresis, there are simpler controllers in the same category, but they may offer less control over reconnect behavior.
FAQs
FAQs
How do I set the cutoff and reconnect voltage?
You use the two-button interface to adjust the low-voltage protection value and the reconnect “difference” window. There is also a factory-reset method (power off, hold both buttons, power on) that can help if you are starting over. If your setup requires exact cutoff behavior, calibration may be needed.
Does the module disconnect power completely when the cutoff triggers?
The relay switches output on and off, but the module itself can continue using battery power after it disconnects. You should cut off the power supply to fully stop the module from drawing power.
What battery types is it compatible with?
It is intended for lead-acid, lithium-ion, and solar panel battery setups. It is not intended for battery packs, so confirm your configuration matches the module’s scope.
What is the maximum current I can switch?
While the module lists a high maximum current before a breaker trips, it also includes guidance to keep real-world use under 8A to protect the relay contacts. Guidance also notes that acceptable current may vary depending on the voltage range.
Will it remember my settings?
User settings are retained even after unexpected power loss, so you should not need to reconfigure every time the system cycles.
Specifications
| Product Title | 12V-36V DC Voltage Protection Module Digital Low Voltage Protector Disconnect Switch Cut Off Over Discharge Protection Module Pack of 2 |
|---|---|
| Category | Electronics > Power Accessories > Power Converters |
| Brand | Seloky |
| Manufacturer | Seloky |
| Model Number | SY073 |
| Color | black |
| Input Voltage | 36 Volts (DC) |
| Output Voltage | 36 Volts |
| Plug Type | Type A |
| Item Dimensions | 4.33 x 3.94 x 0.59 inches |
| Warranty Description | NO |
| Unit Count | 2.0 Count |
| Item dimensions L x W x H | 4.33 x 3.94 x 0.59 inches |
Available variants
Style
- 4PCS
- 2PCS
- 8PCS
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