Voltage reducer question

[chewychevy67]

Ok I was wanting to add this idle up solenoid from a 56 caddy to my 67 4g carb (it works like a magnet when activated). It bolts right onto the carb perfect. I hooked it up to 12 volts and it works as designed to a tee but just as I figured it got hot when on for 30 seconds or longer. So I borrowed a reducer (pictured) that is for heater fans and such. I tested it on mt heater fan and it works just as its supposed to ( dimmed the bulb on my test light) so I hooked it up to the solenoid and it still gets hot (test light stays bright). What can I do to get the voltage down?

[lutronjim]

Google it several on line. Be careful of amps.
https://www.amazon.com/KNACRO-Synchr...22387351&psc=1

[chewychevy67]

I guess I was hoping someone could tell me why this reducer wouldn't work for my solenoid. I an not sure of the amp draw from it but it can't be crazy high I wouldn't think but who knows. If I have to get some crazt big box to put on the firewall to make this work I may just leave it off but it would be nice.

[Andy4639]

Whenever you reduce voltage you get heat. That is how it works. The more amps the reducer can handle the less heat it builds.
Google voltage reducers and look for the highest amp that is small enough for what you are willing to use.

https://www.amazon.com/Converter-DRO...re-bullets-btf

[chewychevy67]

Yeah I figured that but shouldn't the reducer get hot? When I tested the fan the reducer got hot. When I did this idle up it did not just the solenoid did.

[dmjlambert]

That item in your top picture is a resistor. The heat the resistor makes is power dissipation. The voltage drop it has and heat it dissipates is directly related to how much current (how many amps) the solenoid or fan or whatever other load is drawing.

Are you thinking the 56 Cadillac had a 6 V electric system?

Is the solenoid rated for continuous use at 12V, or is it just to pop open the trunk or some other momentary use?

[demian5]

I have a 12-6v converter in the garage.

[dmjlambert]

Sorry, I mis-read your post. You said it is an idle up solenoid. I think that would imply it is for continuous use. How hot is too hot?

[chewychevy67]

Yes it runs continuously when the air conditioning is on. If left on for 5 minutes you can't hold it in your hand. I did it by accident on 12 volt the first time. I was just thinking if it was a 6 volt that's why it gets hot on 12 volts.

[dmjlambert]

That is possible, but likely it would have been a 12V solenoid on a 1956 car. I think you would have to measure the current it is drawing with an ammeter and calculate how many watts of heat it is dissipating.

I don't know if it is practical to determine if the device can actually get rid of the heat continuously and not burn up or melt. You would need to see the published specifications for it to really know what's going on, and you may have trouble finding that. And if you were to drop the voltage sent to it, it would affect the strength of the push it gives to the throttle.

If it were my engine and truck, I would re-evaluate the situation and probably not use it. There are probably current day and more efficient solenoids you could use that won't put such a hot device that close to your fuel system. Are you having problems with the idle speed or just wanting to make use of the solenoid?

[chewychevy67]

No fuel problems just thought I'd use a correct looking era piece to do the job. It actually pulls the arm in when power is hooked up to it like a magnet. When no power is hooked up a spring inside pushes it out.

[chewychevy67]

If this solenoid is supposed to be a 12 volt any idea why it gets so hot and what I can do to keep the heat down?

[dmjlambert]

My guess is there is a short in the windings, and to keep the heat down you would either replace the solenoid with one that is not shorted, or re-wind it with fresh wire to repair it. If you had the electrical specifications of the device, such as how much current in amps it is supposed to draw or resistance of the windings, then you could measure yours and find if it is out of spec.

Since the electric solenoid part of it only operates a vacuum valve and most of the work to move the throttle is done by a vacuum actuator, I would think it would not require very much electric current and would not get hot unless it is defective. That is just my guess.