Relay control issues using common DC-Dc converter for inductive load and controller

I had an earlier problem using the PR54-6 ESP32 for bi-directional control of a linear actuator. I was advised to connect a capacitor between the two leads of the inductive load. This addressed the problem and I was able to move forward with my project. Recently, I have re-worked the enclosure and now am experiencing the same problem as before. When I activate the relay using an app over BLE, the actuator begins moving in the desired direction and then locks in the on position for a few seconds before loosing the ble link with my phone. The earlier response suggested avoiding using a common power source for both the inductive load and the controller supply. This is unavoidable. Please advise on how to address this issue. I have tested it out and the problem is only present when I use the same power source for the system. It abates when I use a separate source for the controller.

You’ll need to clean up the power being supplied to the electronics. Those linear actuators are outputting high voltage spikes that are coming into the power supply input of the board. You could try putting a large capacitor across the board’s power supply input(12VDC). Or you could try a 12VDC to 12VDC converter to clean up the power supply input. Something like this one perhaps although I have not personally tried it:

I have tried using the 56mF inductance repression caps I purchased from NCD at the 12VDC inpput to the relay board, and another at the 5V DC input to the ESP32 ble module. Nothing is working! This is the 15th one I have assembled and shipped out. All are working great and have never experienced any issues once I added the suppression capacitor between the two leads of the inductive load.

Just for diagnostic purposes power the relay board from a separate 12VDC power supply source and see if this alleviates the problem. If so then we know it is in induction problem coming into the controller’s power supply. If it does not fix the problem then we need to look elsewhere.

Inductive loads such as motors found in linear actuators can vary significantly. You can get one that never gives any trouble and get a second that causes all kinds of trouble. This is just the nature of electro mechanical devices, they are all unique in their own way much like a finger print. This is especially true for low cost devices from manufacturers that may not be as picky in inspection of the product.

Let me know what you find once you power the board from a separate power supply source.

That alleviates the problem. Unfortunately I cannot operate this way in the actual application. I am also extremely pressed for space in the controller enclosure so adding some dc voltage regulator is not likely an option, especially one that not very reliable and turnkey.

Can you provide a photo of your wiring setup so we can see exactly where the cap is on the linear actuator?

IMG_2516.HEIC (1.5 MB)

The cap is connected directly between the two leads on the 20amp relays.

I assume the red and black wires connected to the relay COM pins are going to the linear actuator. Is that correct? If so then that all seems to be ideally wired.

Have you tried a larger cap? The one you are using is one of the smallest we carry and may not have the capacity you need.

Could I substitute the 24v-12v DC-Dc converter I am currently purchasing from you with a buck converter like the one attached as a solution to my problem? I want a stable voltage with very few adjustments and no display.

Is the Linear actuator being driven from 12V or 24V? If it is being driven by 24V so it would be on the input side of this buck converter then yes I believe that would work. If the linear actuator is being driven by 12VDC and would be on the output side of this buck converter along with the relay board then that of course would not do any good.