/diy/ - Do It Yourself

>>1234518
The first readings in the previous picture are with a fully charged battery, the idle battery voltage (with just the quad's electronics powered and no BLDCs running) is 12.5 volts which goes down to 11.7 volts with a 48 Amp current draw at full throttle. The motors are rated at 12 Amps each full current draw and I'm assuming there are 15-20% losses in the ESCs. The spec lines up almost perfectly with the results here.

The second set of readings are with a battery discharged to about half capacity, the battery sits at 12.05 volts while idle and goes down to 11.2 volts at max current draw. The problem happens when I go above 60-70% throttle at this voltage level. The motors speed up as I take the throttle up until I get to 11.2-11.3 volts on the battery, then the motor "Resets" and "Bounces" back to a lower speed until the voltage pops back up to the 11.5 volts level, it then tries to speed up again until it gets to the same 11.2 volt level again and the cycle repeats.

From this experiment I concluded that the ESCs I'm using might have some sort of minimum voltage cutoff built into them, so I set up another experiment to test that out. I took the propeller off of the motor and ran it from my bench power supply, I hooked the ESC with an Ammeter in series and measured the current flowing into the ESC at different voltages (randomly selected). The results are in pic related

With no load attached to the motors, the Motors / ESCs operated right down to 10.2 volts which is actually below what's considered safe for a LiPo, below this voltage, the motors powered up once in a jerk and then slowly shut down. I experienced no such cutoff / jerking in this test that I experienced in the previous test and the ESC's battery cutoff seems to be well below the 11.2-11.3 volts that I get down to in the previous test.