"Is it possible to change the battery charge setting on a G500s running Linux Mint 18.3?" If you want to switch the charger circuit circuit setting from "Cautious" to "Commando" and
it's stored in the hardware, your BIOS screen might help. If it's a built-in-to-Windows function, you lose it when you boot Mint. I don't have a G500 to play with.
There's a few tricks here http://batteryuniversity.com/learn/arti ... al_hydride
If you can spare half a day without your computer, pretend it's a new battery you have fitted and the hardware needs to determine new 'empty' and 'full' marks. The manual for your computer really should have a section for this, if not...
Reset 'Empty' Mark: Reboot into a BIOS screen and run the machine on battery power until it switches itself off through lack of power supply.
Reset 'Full' Mark: With the machine kept switched off, connect the charger cable and let the battery charge to maximum.
I would allow at least 8 hours for it to do the job, your computer manual might suggest 12 or 16 hours, or there might be a colour-change lamp to indicate 'full'.
With 'idiot' charger hardware, there will be no change at all. You will have to remember that 59% means 'full' and 5% means 'empty'. With a 'smart' charger and a bit of good luck, Mint will boot and show 100% for full and 1% for 'shutdown'.