"Robert M. Gary" wrote:

I guess my question is; do all planes generate about 13.6v with
accessories on? I also teach in a large variety of planes, but none
have a volt reader in the panel.

According to AC 43.13-1A -- "The voltage drop in the main power wires from the
generation source or the battery to the bus should not exceed 2 percent of the
regulated voltage, when the generator is carrying rated current or the battery
is being charged at the 5-minute rate. The following tabulation shows the
maximum acceptable voltage drop in the load circuits between the bus and the
utilization equipment."

The table indicates that 1/2 volt is acceptable for a steady load and 1 volt for
an intermittent load. This passage is intended to be used to determine whether
wiring is properly sized.

According to that, you should be seeing at least 13.72 volts at the bus, but as
little as 12.72 is acceptable at an appliance that produces a temporary load.

George Patterson
The desire for safety stands against every great and noble enterprise.