I noticed the other day that one of my locos was reading the low track voltage warning in a certain part of my layout. I found this odd, as the other locos seemed to run fine, and then promptly forgot about it and went on my merry way. I was playing around last night and noticed the same thing. With this particular loco, the track voltage is reading, at best, about 11.5 -11.7 volts when the loco is sitting still. When running it over the section of track where I get the warning, voltage drops down to the low 10 range.
I then checked all my other locos. Most read 13.6-13.8 volts when sitting still and drop into the 12's when hitting the poor section of track (I think I just need to add another power drop - but that's another subject). I did have two locos that started in the 12's and dropped to the 11's, and then the one mentioned about that was even lower.
If the track is the same, why would different locos read different voltages? Could this simply be a matter of dirty wheels? A power pickup wire come undone?
I am planning on pulling this loco apart anyway due to it's running a little rough (Bluebox Athearn - possibly a cracked gear), so is there something that I should be looking for?