Power windows
 

I have the Nu Relics power window kit in my car and I have a question. The power wire coming of the harness is about 8 gauge because it uses modern (2002/2017 Silverado) window motors. I have no where to hook a wire that gauge so I hooked it directly to be battery which in turn means they have power all the time. I am ok with this if this is the way it has to be but does anyone know a better way?

Install the power wire to a relay that is energized by the ignition switch.

I have an add a circuit kit from painless but the wires coming out are like 16 gauge

Which is why he said "... to a relay that is energized by ..." HTH.

It is a relay,,..does it not matter the gauge after the relay.

Yes it matters. The relay needs to meet or exceed the current draw of whatever it is to feed. Wire size is a good indicator but actual amperage would be better to know.

That's how a power window knows when to stop going up or down.

Make sure you get a continuous duty relay if you go that route.

Run wire from battery to relay, then from relay to the window motors. Run the trigger wire from the ignition switch to the relay. The trigger wire can be any size as it doesn't carry much current a 14 or 16 gauge wire would be fine. Whenever the key is on you will have power to the window motors, so anytime you're driving the relay will be energized that is why you need a continuous duty relay. The relay will come with proper wiring instructions.