if I were to fly for 10 minutes and run my battery down to say 70% and I need to fly the next day can I charge the battery from that point or do I need to run the battery down more?
I always top my batteries off. I have read somewhere, if you take off with less than 100% and something goes wrong in-flight -- you are on your own. Battery temperature/outdoor temperature, cycle count, etc all affect endurance and actual run-time and the percentages become questionable depending on extremes like hot or cold. -- YMMV!
If you want to run the batteries down more before charging, start the motors and let them run until they time-out a few times and let the cooling fans run. I only recommend hovering a drone IF outdoors -- this would be best if trying to drain the battery. You'll find out quickly that starting the motors over and over isn't fun and something you probably should not be doing more than a few times anyway.
Second question if I store my Evo in it's hard case with its extra batteries and the batteries discharge at the Six-Day point will they cause any problems,like heat?
Simple answer - no.
If the battery is "heating" during storage/discharge related to storage -- I would be worried. Otherwise a warm battery during use and charging should be the only "heat" you should encounter.
edit to include battery temp, with a drain from EVO being on in a 68 degree room. I don't think I have actually grabbed this battery and thought anything about "heat".
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