[PaulD]

please do not confuse watts DC with watts AC. The easiest way to figure out exactly what you are drawing (current) is to use an ammeter inline with power cord coming off the battery. You can temporarily wire the ammeter in as the fuse to see what the draw is. Wire size is probably ok (would actually have to see what the current draw, length and wire gauge is) but most of the voltage drop in these cases is due to poor wiring connections.