Adding Power to Utility Trailer

I did the same although my trailer came with the interior lights already installed. The interior lights were hooked to the running lights under the assumption that you would need the lighting at night. I, however, removed the little brake battery and mounted a battery tray on the tongue. I put a terminal strip on the inside of the tongue, under the battery tray, so it would be protected and made all connections at that point. I ran a new 12v power wire inside the trailer to power 12v outlets and the lighting. I've added a 30 amp breaker at the battery positive terminal since these photos were taken.