I am a new guy in the area of electric flight. I have read that it is a good idea to draw down a battery to 70% to 80% of it labeled capacity - mAh. Am I on the right track to maintain a battery in good condition? Is there a charger/measurement tool available to measure the current level of a battery?
Thanks for the information.
Depending on how you mean this it could be a old rule left from the old NiCd days. Those batteries had a memory effect. If you did not discharge them all the way they would develop a memory and over time would hold less and less charge. So it was common to run them down before charging them.
If you are talking Lipo batteries then running them down more than 80% will likely damage them. Actually best practice says you never get them below 3V per cell, resting voltage. If they get below 2.5 they start to take damage and the difference in charge level between 2.5 and 3 ain't much.
To measure the load your motor is putting on your battery you use a wattmeter. This is the one Iuse:
If you want to measure the charge level of a battery you use a battery checker:
For more info, read here:
EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT