Crutschow, I learned how a relay works from my work with the pid controller. The output from the pid to the relay was 5 volts, and that opened the full voltage. What I'm not clear on in your proposed circuit is where I'm getting low voltage (ie 5 volts) to run to the switches and relay in order to signal it to open the full 20 volts at the relay. I hope I'm being clear enough to understand. I'm very novice at this sort of thing. I appreciate the help

 

The battery is 20v. the buck converter steps it down to 12v. There are four, 20 watt leds.

where I'm getting low voltage (ie 5 volts) to run to the switches and relay in order to signal it to open the full 20 volts at the relay.

Relays come in many different operating voltages, not just 5V.
So you would be switching the battery voltage to control the relay, but 20V is an odd battery voltage.
What kind of battery is it?

You could use a simple LM317 regulator to drop the 20V to the 12V coil relays I referenced.

 

It's a 20v lithium ion rechargeable battery made by DeWalt for power tools.

 

There are four, 20 watt leds.

Check your LEDs to see if they're 20W equivalents or 20W actual.

A 60W equivalent LED bulb for a 120VAC light fixture actually dissipates more like 10W. It gives the same number of lumens as a 60W incandescent bulb, but isn't actually a 60W bulb.

 

The leds are 12v flood lights for landscaping. I have used a buck converter with these and the dewalt battery to make portable jobsite lighting. I have used the same set up for trailer lighting with a simple on/off switch.

 

A picture of the LED showing the brand and markings might help.

 

Dennis, these are 20 watt lights. My experience shows they will be close to that if not spot on.

 

Mr Chips, I don't have them yet. 12v 20 watt flood lights. they are basically a board with a bunch of 2835's on it backed by a heatsink/housing with a glass cover.

 

Crutschow, I think I begin to understand what you are saying. Could you draw or describe the circuit including the lm317 to drop voltage for the 12v relay?

 

You don't need a regulator to drop the voltage to the relay coil a resistor will do as in this schematic:

 

12V DC/AC 20W LED floodlight would be 20W consumed power, i.e. just under 2A @ 12V.
That translates to about 1.2A @ 20V.

 

Definitely a bit more complicated than your original suggestion. I'm looking for switches that I could use to do it that way. In this more complicated version with the relay I would need help to know where to hook what wire on the relay, as well as calculating the resistor value.

 

12 volt relay coil is generally no more then 150ma so those .6 amp switches you listed would be fine.
One you select the relay it's a simple calculation to determine the resistor value.

 

Look specifically for 12 volt automotive switches. They will handle the current easily.

 

Using a buck regulator with an enable input gives you the best of both worlds. The switches need only carry the negligible leakage current of the enable input. No relay needed, minuscule draw when off.

 

12 volt relay coil is generally no more then 150ma so those .6 amp switches you listed would be fine.
One you select the relay it's a simple calculation to determine the resistor value.

Would this way be better than the way you suggested first?

 

I think so unless you can find some heavy duty switches. Which might be more costly then using the relay.

 

Definitely a bit more complicated than your original suggestion. I'm looking for switches that I could use to do it that way. In this more complicated version with the relay I would need help to know where to hook what wire on the relay, as well as calculating the resistor value.

The connections are shown in post #30.
For a typical 12V auto coil current of 200mA, the resistor value would be about 40Ω, 3W.

 

I ask because I found switches rated at .25amps at 125vdc. They are also rated at 5amps at 30vdc. I'm assuming they would be rated a bit higher amps at 20vdc than they were at 30vdc. Does this sound right?

 

I ask because I found switches rated at .25amps at 125vdc. They are also rated at 5amps at 30vdc. I'm assuming they would be rated a bit higher amps at 20vdc than they were at 30vdc. Does this sound right?

Yes.