Thread: Outputs don't have enough power to push relays

I'm not sure if my question is related or not so i apologize in advance if it doesnt.. but is it possible that either then FB or a relay will weaken its output over time(< 2 years). I have a very strange thing goin on with my lilliput (flickers on/off at start, press touchscreen and the screen turns off). The screen along with my Directed HD Radio is connected to the FB via the FB store relay. I took a multimeter to both sides of the relay. The input (connected to molex for clean 12v) is 12.48 with the engine running and 11.02 is the output. Sounds like quite a drop off doesnt it?

Okay, I just tried on windows. I tried in both MDX using a simple ninja kitty setup and also a setup with a .net app someone posted to the forums a while back with a project name FBDemo. I tried every single output. None of them worked output the right voltage. Also, on output #2, when I plug in a relay its LED light dies until I unplug/replug the fusion brain.

Overall, unless there is really something I'm missing in the software, I think there is something causing ridiculous resistance somewhere. I'm open to any suggestions though.

Any ideas, or am I going to need to send this thing in for repairs?

My guess is your power source does not have enough amps. Voltage readings are only half the equation of total power consumption, you need to figure out how much current (amps) your source can deliver. 12v 100ma won't close a relay, however 12v 1a will. Heck you can even close a relay with 5v if you have 2.5a behind it.

12v x 1a = 12w

or

5v x 2.5a = 12.5w

Anyway, you don't have enough current, for example, a car starter operates from 12v, but it sure as heck is not going to turn over with a 12v drill battery.

Originally Posted by blk02si

My guess is your power source does not have enough amps. Voltage readings are only half the equation of total power consumption, you need to figure out how much current (amps) your source can deliver. 12v 100ma won't close a relay, however 12v 1a will. Heck you can even close a relay with 5v if you have 2.5a behind it.

The relays here actually only draw 70 ma. I tested them with a computer power supply and a multimeter and it worked fine wired directly to the psu through the multimeter and it only drew 70 ma.

Originally Posted by blk02si

Anyway, you don't have enough current, for example, a car starter operates from 12v, but it sure as heck is not going to turn over with a 12v drill battery.

That's what I thought at first too, but then I plugged it into a fully charged 85 AH deep cycle battery. Still nothing. The battery definitely has enough power, it pushes the relay just fine when the relay is wired right to it. The problem is the current is not making it to the outputs on the fusion brain. I've been talking to the fusion brain guys and they're sending me a replacement since it seems like there is definitely something wrong.

That battery should be fine then, looks like your FB is culprit.

A quick Q for you guys, I am reading these threads because I want to buy a FB. What is the difference between the v4 and the other one that mp3car sells in their store?