***NO LONGER WORKING AFTER SU15***
Looks like Asobo has changed something (broke something?) which prevents this workaround to function as intended. FSW has now instead wrote a workaround into the L35A which allows to call the GPU anywhere which keeps the battery at 100%. Currently this workaround is only available through FSW Discord, at least until the next version of the L35A is released. This means that this mod is now irrelevant and obsolete. Will discontinue support on it until it becomes relevant again.
This is a PowerShell script that will modify the flight_model.cfg, specifically the line "interactive_point.1" to disable the standard MSFS GPU. This means that you will no longer be able to call the GPU from the ATC ground services menu, nor use the GSX GPU, and can only use the custom GPU that you turn on from the tablet EFB in the cockpit. This will allow you to turn on the GPU anywhere you park, regardless of whether the current parking spot has a GPU available or not. There is included a script to revert to the original, which will again allow you to call the GPU from ground services and GSX, but this will restrict the GPU to only be enabled when there is an available GPU at the current parking spot. According to the developer, this is a restriction from Asobo whenever using the default GPU services.
The readme file contains all instructions, as well as the script code.