[Al Skierkiewicz]

Hadi,
The power supplies built into the PD should work even with heavy battery draw. Remembering that any series resistance will drop voltage as the load current increases, teams should check for loose hardware on the battery terminals, PD terminals, loose crimps on the Anderson plugs and damaged contacts on connectors. It is quite common for teams that use the supplied alligator clips on the battery chargers to scratch the contact surface of the Anderson connectors and raise the contact series resistance. It is highly recommended (read that as do it) to change the clips to an Anderson connector. There is always the possibility that the battery is defective as well. Checking with a voltmeter will point you to the problem I think.