driving, 80mph, roughly 4k rpm. Battery, brake, and whatever the one is on the right that looks like a radiator come on
look down at my turbo timer which is showing voltage, im reading 13.8-14.0
when the voltage drops from 14, the lights go out.

this happened about 4 times on the way to the track

drove home at 65mph a little over 3k rpm steady the whole way no lights, battery voltage never went over 13.7

i had the alternator and battery tested and they tested fine (test was done at idle and 2k rpm per the machine)

what does these lights coming on mean? is 14.0 voltage safe?
what range of voltage is safe?

thanks a lot