I've been playing around with circuitikz, and am really loving it so far. The only problem is that I really don't know how to adapt it when there a symbol that I want is not present.
For example, I would like to draw the following circuit:

The specific problem that I am having is that I don't know how to terminate both ends with a +5V and -5V symbol. This is the best that I could come up with:
\documentclass{article}
\usepackage[american voltages,siunitx]{circuitikz}
\begin{document}
\begin{circuitikz}
\draw (0,0) to [battery,l=\SI{-5}{V}] (0,0)
to [empty led,l=LED1] (0,3)
to [R=\SI{510}{\ohm}] (0,5)
to [battery,l=\SI{5}{V}] (0,5);
\end{circuitikz}
\end{document}
Another related question:
How do I flip the LED direction in the code above without starting from the top (0,5) and going to (0,0)? I tried something like [empty led,l<=LED1] but that didn't work.
Thank you for any advice or suggestions!

