Dear friends, I bought an hyperion 720duo3 charger. After setting up I tried to charge the 2s lipo battery, all setting were good. when the lipo starts charging, in port #1 appears the message: input voltage error, the voltage is about 26V and the power supplier goes to 9V instead of 13.8.

In port #2 the charging process is normal, so the problem is only in port #1.

Anyone can help me in solving it?

If I remember correctly only port one reports that, use a multimeter and confirm the power supply voltage

You can also wire it up to a 12v car battery and try it and that will let you know if it's your power supply giving you trouble or not.