Actuator Control With Two SPST Relays...Troubleshooting Help

[DaveWilliamsTX]

I've created a simple motor control board with a couple of SPDT relays and deer-feeder timer/controllers I had laying around. The use-case is to open and close my chicken coop door actuator at the appropriate time.

The circuit works great on a cheap 12v bench-top power supply. I get + or - 12v for 10 seconds out of the motor control lugs on my board when the timers go off. When I connect it to a fully charged (12.26v as measured with my multimeter) car battery, I get no voltage differential between the motor control lugs when the timers go off. I can hear the relays tripping in both cases, but on the battery I get no juice on the control-end. Any ideas?


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I found this thread:
https://www.electro-tech-online.com...verse-polarity-to-a-motor-using-relays.42524/

and implemented a design based on the first couple of posts. I've attached a diagram of my circuit.

Here's the relays I used:
http://www.radioshack.com/product/index.jsp?productId=2062482

Here's the linear actuator:
**broken link removed**

Here's the model of the timer:
**broken link removed**

Thanks for any/all input - Dave

 

[ChrisP58]

I'd double check your wiring. There is no reason that it shouldn't work off of a battery if it works on a bench supply.

On thing in particular to check, is to see if the negative connection is solid from the motor through the relay to the battery. Many bench supplies have their negative terminal tied to earth ground. If you circuit has some connection to ground also, the negative connection might be getting completed by a different path. If so, then it wouldn't work from the battery that lacks an earth ground connection.

 

[DaveWilliamsTX]

So, my drawing shows the NO pins on the relays as being wired high, but I had them wired low. Switching them to be wired as drawn fixed it...still seems weird to me...

Thanks for the reply, though.