Low power module supply voltage


i bought last week a 3DR power module and try it yesterday.
the power module only powered the apm2.6 (arduplane 3.1) . Sevos are powered by ESC
after a no problem flight, i download via mavlink the log of the flight and when i read the CURR:VCC value i have the surprise to see only a average value at 4.6 V with min value arround 4.4V

I excepted 5.3V and i think 4.6V it’s very low value (and dangerous value) .

question : does CURR:VCC is the good log return value ?

This evening i will do a direct voltage mesure with a multimeter to know exactly the 3dr output voltage value

ps : i’m french, sorry for my poor english

I did some another measurment.
in the output of the power module i have 5.1V : it’s ok
between the + and the -, in the input port (where my recepter is connect) i have 4.6 V
why do i loose 0.5V ==> I don’t understand where is the problem.

can you help me?

Do you have jumper J1 installed on the APM?

thanks for your answer
no i don’t have the jumper j1

yesterday i’ve cut the 2 +5V wires and the 2 - wires.
i’ve connected there wires to the + and the - of a servo connector and i have plug this connector to an input free place. i have now 5.1V to the CURR:vcc log record.

is 0.5V a normal shutdown in the zener diode ?