There's really no need to - you have 2 choices:
1. Run GSam and set the low alarm to 40%.
2. Keep running the battery down to 15% and buy stock in a battery company. Lithium batteries last longest if kept between 40% and 80%. Running one down to 15% constantly will kill it quickly. (Not to the point that it needs to be recharged, to the point that it needs to be replaced.)
Lithium batteries are light. Lithium batteries can be made very thin. Lithium batteries can not last long when discharged deeply. If you want a battery that can regularly be discharged to 0%, you need a gel cell. One to run a phone would weigh a few pounds, and be a bit larger than a cellphone.
10-23-2018 12:49 PM