Solenoid Problem?

[adrenaline503]

I bought a 100 amp 12v solenoid from West Marine the other day to use a switch for my aux fuse box. It is a 4 terminal model if that matters. I understand the mechanics involved, and tested the actuation with a 12v power supply at work. No problem there. I wired a switch directly from the battery to the "switch" terminal on the solenoid. I then grounded the other terminal to the negative side of the battery. When I flip the switch, all my lights dim by at least 50%. Then a few seconds later that "hot electrical" smell starts up. None of the wires seemed to get hot, nor did the solenoid itself. The switch is a Hella light model that I had lying round, the type that runs a relay all the time. Does the switch circuit in a solenoid pull more current than a relay? I had thought not. Maybe I am grounding out somewhere, but I check all my wires and it looks fine. Any ideas?

 

[Travelmore]

What is the model of the solenoid. They can draw quite a few Watts. Also were you testing it with a load (what were you switching on and off)?

 

[adrenaline503]

I believe it is this model:


http://www.westmarine.com/webapp/wc...rue&storeNum=5002&subdeptNum=9&classNum=15802


I tested it both times unloaded.

 

[ExpoMike]

In reality this type of solenoid is known as a "Ford Starter Solenoid". I can be used as a continuious duty solenoid that would have a large current flow that would not be handled by a typical relay.

The drawback to this solenoid is it takes much more current to keep it activated unlike a relay. Most 30amp relays take a couple hundred miliamps to activate the relay. The switch that Hella uses in their kits are designed for this type of relay. The solenoid you have typically will take 5-10 amps to activate and a couple amps to keep it "on". Your poor little Hella switch is not even close to that rating. You'll need a heavy duty switch to run this.

As for wiring, I am assuming you have positive in from the battery and out to the fuse block, running through the larger terminals on the side. The two smaller terminals, typically marked + and GND (but not always), the ground wire is going to body ground and the + one should be connected to your switch, which in turn is connected to a 12 volt power source. I do believe it makes a difference which way these two terminals are wired so if backwards, it could be shorting and causing the lights to dim.

Hope that helps some.

 

[BigJim]

Solenoid

I am curious how you can connect a solenoid as shown in the link up with the polarity wrong. Unless the solenoid has a diode in it it makes no differance how it is connected.

And I disagree with the second post as to the current rating on the pilot duty switch. In any case if the switch is suspect use a piec of wire to energise the solenoid.

And if there was a short of any kind you would hopefully blow any size fuse, burn up some wires and know for certain there was a problem.

Pos and neg to the coil.
Source and switched load.

That solenoid might draw 2 amps if that. I suspect if the load side lights dim there is another problem in that there is not enough current available, period.

 

[THATSALEXUS?]

If that is indeed the solenoid you are using:

• The polarity of the coil contacts does not matter
• The switch you are using may very well be inadequate for a solenoid vs. a relay. A solenoid usually draws up to 5 amps, a relay 150 milliamps. The switch should indicate it's current rating somewhere on it.
• If the solenoid is wired properly, there is no way that it's mere introduction to your electrical system has caused your lights to dim. There is some other current limiting factor.
• If the solenoid didn't get hot, you didn't have it on long enough