Some of the interesting things I have found seem to indicate Meade had 3 versions of the LX200. Originally it seems they had a 12V version with a smaller object library. They then increased the recommended voltage and increased the object library. The final version then had a couple of current limiting resistors added to the motors. These are the 2 white objects on the lower left of the image. I read it on the internet, so it must be true .
I have the final version and know I have the resistor pack. It originally ran great till the declination capacitor failed. Currently it has run great with the 18V for the past few months. I intend to keep using 18V. The voltage others might use I would think depends on the internals of the particular scope. I would think if you are unsure, having a good steady12V power, and the capacitor replacement should keep the scope happy. Under 12V might cause some issues.
Just in case you are a lucky owner of the 16", I have read that you must use 18V.