Pay in installments of $5.13 with
,
and
Shipping Estimate
USA
- USA
- CAN
- USA
- CAN
Ships within 48 hours · Estimated delivery Aug 20 - Aug 25
Promo Codes Available:
For Your Every Summer RSVP, with Code: SUMMER15
Description
SSR-40DD DC to DC Solid State Relay - 2 PackSSR 40DD Solid State Relay Key Features Completely Silent Operation: Unlike traditional mechanical relays, this Solid State Relay (SSR) uses internal semiconductors to switch the load. This means zero clicking noises, zero mechanical wear, and zero electrical arcing. Opto Isolated Safety: Features internal optical isolation between the low voltage control circuit and the high voltage load circuit, completely protecting your sensitive microcontrollers
SSR-40DD Solid State Relay
Key Features
- Completely Silent Operation: Unlike traditional mechanical relays, this Solid State Relay (SSR) uses internal semiconductors to switch the load. This means zero clicking noises, zero mechanical wear, and zero electrical arcing.
- Opto-Isolated Safety: Features internal optical isolation between the low-voltage control circuit and the high-voltage load circuit, completely protecting your sensitive microcontrollers or PLCs from high-voltage spikes and feedback.
- High-Speed Switching: Capable of turning on and off infinitely faster than a mechanical switch, making it highly suitable for precise PID temperature control and PWM (Pulse Width Modulation) applications.
- Durable Epoxy Housing: The internal components are heavily potted in a flame-retardant industrial epoxy resin, making the relay highly resistant to severe vibration, moisture, and dust.
- Protective Safety Cover: Includes a clear, flip-up polycarbonate safety shield over the screw terminals to prevent accidental short circuits or dangerous physical contact with live DC wires.
Product Specifications
- Relay Type: DC-to-DC (DC Input controls a DC Load).
- Model Number: SSR-40DD.
- Control Input Voltage: 3V to 32V DC.
- Load Output Voltage: 5V to 200V DC.
- Maximum Load Current: 40 Amps (Requires adequate heatsink).
- On-State Voltage Drop: ≤ 1.5V.
Universal Compatibility & Applications
This heavy-duty DC solid state relay is a staple for custom power control and industrial automation:
- Heated Beds (3D Printing): Frequently used to safely route heavy DC current from a power supply to a 3D printer's heated bed, bypassing the fragile motherboard MOSFETs.
- Solar & Battery Systems: Excellent for custom charge controllers, battery disconnects, or switching heavy DC solar panel arrays.
- DC Motor Control: Used to switch high-torque brushed DC motors in robotics, CNC machines, or industrial actuators.
- High-Power LED Arrays: Perfect for PWM dimming of large 12V or 24V LED lighting banks.
When to Use or Upgrade
- Mechanical Relay Failure: If your standard mechanical relay has welded its contacts shut from high-current arcing, upgrading to an SSR completely eliminates this failure point.
- Relay Stuck "On": When an SSR fails, it almost always fails in the "closed" (always on) position. If your heated bed or motor refuses to shut off even when the control signal is removed, the internal triac has burned out.
- Switching Speeds: If your project requires a switch to toggle multiple times per second (like a PID temperature loop), a mechanical relay will physically break in a few days. An SSR is required.
Installation & Wiring Tips
- Heatsink is MANDATORY (CRITICAL): SSRs generate significant heat. If you are drawing more than 10 Amps continuously, you must mount this relay to an aluminum heatsink. Pushing 40A without a heatsink will literally melt the relay and cause a fire.
- Thermal Paste: Always apply a thin, even layer of thermal compound (PC processor paste) between the metal bottom of the relay and the aluminum heatsink for proper heat transfer.
- Strict DC Polarity: Unlike AC relays, DC relays are strictly polarized. You must carefully observe the Positive (+) and Negative (-) markings on both the Input (control) and Output (load) sides. Wiring the load backward will destroy the relay instantly.
- Load Derating (PRO TIP): For inductive loads (like heavy DC motors with magnetic coils), the starting current spikes massively. It is highly recommended to derate the relay and only run inductive loads at 50% of the maximum rating (i.e., keep continuous motor loads under 20A for a 40A relay).
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.2 ★★★★★
Based on 25 reviews
Sort
Product Reviews
★★★★★ 5
works as advertised!
Size: 1 Count (Pack of 1)
I purchased this kit to renew the headlights on my 2016 Nissan Frontier pick-up. The headlights had become slightly oxidized and dull -- not that bad but it was bothering me and for the price of the kit I figured it was worth the effort to attempt to renew them.
All I can say is -- WOW, what a difference. The end result looked like new -- clean, brilliant and bright.
Read the directions (2 or 3 times) and follow them EXACTLY. Total time for me from opening the kit to being done was about 2 hours and I was taking my time.
This kit is different in that the final step applies a UV resistant coating which really makes the glass super transparent.
Great investment in the time and money. I can't stop admiring my new (old) headlights!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 14, 2026
★★★★★ 5
Incredible Results! The "Z-Line" is Back!
Size: 1 Count (Pack of 1), Size: 1 Count (Pack of 1)
I’ve tried a few "wipe-on" fixes in the past, but the CERAKOTE® Ceramic Headlight Restoration Kit is in a completely different league. If you are tired of hazy, yellowed lenses and weak nighttime visibility, look no further.
📖 Instructions & Ease of Use
The first thing that stood out was the clarity of the instructions. The kit breaks everything down into a simple, step-by-step process. Even if you aren't a "car person," the directions are foolproof. They don't just tell you what to do; they explain why each step matters, which gave me the confidence to get the job done right the first time.
✨ Restoration Effectiveness
As you can see in my Before and After photos, the transformation is night and day. My headlights went from a dull, oxidized yellow to a factory-fresh, crystal-clear finish. It didn't just "clean" them—it completely rejuvenated the plastic.
🔦 The Real Test: Light Output & Beam Pattern
The most impressive part isn't just how the car looks, but how it performs at night. I’ve included a photo of my car parked against a wall in the dark to show the comparison:
Passenger Side (Restored): You can see a sharp, distinct cutoff line and the perfect "Z-line" pattern. The light is focused exactly where it needs to be on the road.
Driver Side (Not Restored yet): The light is completely distorted. There is no cutoff, just a messy blob of light that scatters everywhere, likely blinding oncoming traffic while providing less actual visibility for me.
Final Verdict
This kit doesn't just make your car look better; it’s a genuine safety upgrade. Seeing that crisp Z-line back on the wall proves that the clarity is internal as well as external. Highly recommended!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 15, 2026
★★★★★ 5
My first experience using one of these, it worked VERY well!
Size: 01- 24pcs (Classic Green)
Our tire picked up a large bolt that we could hear clicking when we were driving, and our low pressure warning light lit on our dash. Yep---tire was 7 psi below recommended (32 down to 25), I could not see the leak site and we were far from home so I drove some more then checked again. Just one more psi down over those 20 miles so all the way home (100 miles more) we drove. By that time I was able to find the leaking spot and see the bolt head had ground off or broken off. It was just a very slow leak, a few psi more per day, but I knew it would only get worse.
I decided to order this kit after reading reviews & don't believe the haters. It worked so well for me it is worthy of my time to write of my experience. The tools to me all seem robust & top notch, especially for the price. There are multiple straps inside the nice case to secure them in place. YES---you have to use your own pliers but come on---don't ding the product when that is spelled out clearly in the description!
So---I had the huge benefit of allowing a full day in my own garage to do this. I pulled the wheel since others had said it much easier that way. I then used my pliers to pull the remaining bolt out of the tire and immediately heard the air rush out. "That's a pretty big hole!" I thought. I reamed the hole easily, lubed the plug installation tool, centered one plug strip in the tool and pushed it in all the way except about 1" left outside the tire. I aired up the tire after about 5 minutes of what I thought would be "cure time" but don't know if that's necessary. After my initial inflation to full pressure the tire actually did leak down a bit over a few hours. A few cycles of this and it has stayed sealed completely ever since....not even down a pound! I assume this was the time the vulcanizing compound (already applied to the plugs) took to seal to the tire....maybe if I had driven on it right away (heat generated and varying forces) it would not have leaked out. My initial fear of "huge hole" and assuming I might need to plug twice or use 2 plugs the fear was unfounded.
I will update this post if something goes awry. For now I am one happy customer as well as a happy camper. I'd strongly recommend this kit based on my experience, plus I have the remaining patches & tools if needed again. I hope this helps you with your decision/choice.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on July 27, 2024
★★★★★ 5
Lifesaver Tire Repair Kit Every Car Should Have One
Size: 01- 24pcs (Classic Green)
This 24-piece tire repair kit has already saved me and my family multiple times. My car literally can’t go without it now. It’s compact, well-organized, and the tools are sturdy and professional-grade. Having this kit has saved us from costly trips to the tire shop, time wasted going back and forth, borrowing another car, or risking driving on a flat tire. Seriously, everyone should have one in their car, just buy it and keep it there. Trust me, it’s a game-changer!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 12, 2026
★★★★★ 4
Had no issue and it was very easy to use. It has been a week and no leak.
Size: 01- 24pcs (Classic Green)
Easy to use and its been a week and no leak. The kit is great and easy to use. The hard part was for me to get the screw out of my tire because the head was half gone. Once I got the screw out I followed the instructions and reamed the hole and inserted the plug and trimmed the plug.
If you plan on keeping it in your car you probably should add a screwdriver and/or pliers to get the screw out of the tire and a razor to trim the plug once it is in. You really need a razor to trim the plug I tried with a knife but the had to get a razor.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 5, 2025
recommand products
Ultra Cotton Long Sleeve Tee - Buckle Bunny
30.27
Saint Joseph's University Diploma Frame - Cherry Lacquer - No Embossing - Black on Crimson mat
194.00
University of Tennessee Martin 5 x 7 Photo Frame - Cherry Reverse - w/UT Embossed Seal & UT Martin Name - Single Black Mat
79.95
White Linen Waist Apron
27.00
University of Tennessee Martin 5 x 7 Photo Frame - Mahogany Lacquer - w/UT Embossed Seal & UT Martin Name - Single Navy Mat
79.95