A couple of years back, I took my bed room reading lamp off-grid, using some car LEDs.
http://ecorenovator.org/forum/lighti...mps-house.html
It's still being used nightly and it works okay. But I've noticed the light is a bit on the blue side (colder?).
It's not the warm light that we get from our 120Vac LEDs used around the house.
The diameter of the wire wasn't considered. I used a small size wire, since the run was only about 12 feet.
The power loss of the wire that short is so low, it wouldn't be noticeable.
Actually, the 100 ft run from the little PV panel on the tracker is about 2 ohms!
Here's a pic of the panel used for the reading lamp. (with charge controller and small SUV battery).
But, so far both of my old car 12V PV charged batteries are working fine using a small wire gauge.