I purchased an Acer V15 Nitro VN7-592G last week. It is the 16gb RAM model with the full HD display. I previously owned a Sony Vaio F series laptop, and had to sell it off due to a similar slightly similar issue where the CPU would throttle itself to 770 mHz on battery regardless of remaining batter level.
So far, I am grateful of the fact that my V15's i7-6700HQ can run at its turbo frequency, and doesn't lock its clock speed to 770 mHz on battery power provided the charge is greater than 40%, unless I switch to power saving mode.
However, only yesterday I observed that the computer would get extremely slow once the battery level drops below 40% due to the CPU throttling itself to 790 mHz according to RealTemp, and Windows Task Manager. I turned battery saver off, and changed the power mode to high performance where all CPU parameters were set to 100%. This had no effect, and the CPU just locked itself to 790 mHz unless I plugged in the laptop, and ran it again on battery power once I was at more than 40% charge.
I find this highly inconvenient since the primary reason why I sold my dated (and over-priced) Sony Vaio to purchase my first Acer machine was due to the Sony's poor performance on battery life, their (Sony's) lousy customer service, and the fact I needed a powerful machine with consistent performance whether being run off battery, or AC power since I plan on using the laptop away from the convenience of an AC outlet to edit, and convert high definition AVCHD videos that use up a lot of CPU bandwidth.
If you own a V15 series, please do report your findings on this issue, and please do let me know if there is a way I can disable this form of CPU throttling either through a firmware update, or by digging through the BIOS settings becuase it really defeats the purpose of spending more than $1,000 CAD on a flagship machine.
FInally, if this issue if not fixable, are there any reputable laptop 19 volt portable power banks available that can top up my battery?