so remember i said i was getting ~3-5 min with my 1500mah batteries on my quad, depending on if i had the gitup w/ waterproof case on top? well, i had my low battery alarm set at 3.7v. if i landed when it was going off, the resting voltage would come back up to about 3.80-3.85v, and that's where i was stopping it. but then i read a little more about lipo batteries, and how low you can safely discharge them. i set my battery alarm to go off at 3.5v instead. practically DOUBLED my flight time to about 10 minutes (not doing anything crazy, just learning to fly), and resting voltage bounces back to about 3.7v once i land. granted, this wholly unscientific test involved me going to an open field and just practicing flying back and forth, fighting the near-constant wind in one direction. i crashed a few times of course, and lost one of my battery alarms in the process (glad i bought two!), and only got one flight on each of the three batteries, but i seemed to get a good 10 minutes out of each battery. even the one that had been giving me a lot less flight time before the alarm went off.
my theory is that before, i was only taking off a surface charge during each flight instead of an ACTUAL deep charge, so now that i'm giving the batteries some actual exercise, they're working better. not surprisingly, they take longer to recharge too. of course i'm using a cheap little "imaxRC B3" balance charger that came w/ my quad kit, and it charges each cell at around 700ma - i'm ok with that though - sure, it's slow, but slow charges are apparently good for the batteries. and it consistently gets each cell to 4.18-4.20v, so i'm ok with that. If I get more batteries, I'll probably invest in a better charger, but for now this is fine.
so maybe now i don't need to buy a
3000 mah battery for extended practice time. i AM still planning on rebuilding my quad to open up the cavity inside the frame to allow me to put the battery inside the cage of the frame for better protection and lower center of gravity. this will also allow me to have better access to the USB port on the flight controller. i may even mount the FC (in its hard plastic case) vertically in the front compartment to act as a dividing wall between the camera/VTX and receiver, and what will become the battery bay in the rest of the frame. also planning on mounting the power distribution board between the bottom two layers of the frame, which will provide more protection for some of the wiring, and also make room for batteries. i plan on taking photos along the way so you can get a better idea of what i'm talking about.
while i'm at it, i may upgrade my receiver to the R9D, which can send telemetry back to my transmitter. maybe it'll eliminate the need for a low battery alarm. i can program my transmitter for all sorts of things, and if it sends back voltage, then i can set an alarm (which not only beeps, but also vibrates the transmitter!) so that even if i'm flying FPV and it's out of my range of hearing, i'll still know when it's time to land.
Hmm...
$8 for 2 more battery alarms or
$16 for a new receiver with telemetry? they're cheaper from china, but the price difference is surprisingly small (only about $1 less), so it's worth it for shipping that will get here this weekend instead of this summer. maybe i'll buy both.
![Stick out tongue :p :p](https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f61b.png)
and this time i'll attach the low battery alarm to the quad with zip-ties instead of velcro.
i guess the next thing for me to learn is librepilot, so i can download my existing settings from the CC3D before i mount it in a different direction. I like the way it flies now in the different rate modes, and don't want to lose that when i move the FC.
oh one more thing - i tried letting the quad hang down pointed straight at the ground instead of horizontal when i turned it on - it didn't care - beeps were normal, and it flew normal. so apparently mine's also set like yours,
@TechTronic9000 in that it already knows what level is, and doesn't calibrate every time you power it up. so that's handy.