Nirvana has several major issues with the power. We were forced to made the mods ourselves as Flysky did nothing to fix this so far.
Main problems that we aimed to solve:
a) external module from Nirvana settings menu can't be switched off fully, power to ext module remains 3V.
b) main circuit has no DC-DC booster so if battery drops 3.4V (underload 3.2) it becomes unstable and dies and also batteries are used not depleted fully. It is not efficient.
c) ext module stepup is powered from the same point as main circuit so that is why crossfire and other modules can't run on high power - ext module makes the power drop to ❤.3v for main circuit so it dies if batteries are not full or crossfire is on full power.
d) polarity protection circuit uses crapy transistors, that make voltage drop ~200mV. That could be saved by using mosfets.
Detailed instructions how to fix these problemas are attached as PDF on RCgroups Nirvana forum. These mods requires:
a) Splicing 2 FETS for ext module, to cut power properly when module is not uses
b) Replacing two polarity transistors to FETS, to reduce voltage drop by 200mA, shortening 2 uneeded transistors
c) cuting main circuit powering line that comes from transistor switch that powers radio, and inserting there DC DC stepup
d) rerouting ext module input to the input of installed new stepup
e) rerouting battery level voltage divider resistor to the same stepup input.
Then we got the radio that can be used properly and safe:
a) properly shuts on/off ext module
b) uses batteries to full depletion, and runs on stable 5V from stepup
c) can handle ext module (Crossfire, Lora 1W) with higher power demand.
Detailed instructions are on this RCgroups page:




https://www.rcgroups.com/forums/showpost.php?p=43209073&postcount=2996