Testing My Diode

I made this little simple connection. One 7V battery connected with a 4V battery, but with a diode connected on the positive that directs the flow to the bigger battery. I will leave this for a long time, and I should get a read of the higher battery, above of 7.38V and a read of the lower battery, under 4.03V. If this is truth, I succeeded in using a diode.