q
lvl.1
Austria
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hi,
I haven't completed my F550 yet and therefore I have not practical experience on this model yet (or any other hobby class multicopter). Im only posting here because I have years of experience driving RC cars with lipos of all sizes and there is no other answer yet.
I was wondering about the voltage settings myself just an hour ago when I first installed the naza software on my PC.
I'm using a 4S lipo. nominal voltage: the usual 14.8V
idle voltage on the pack as it came out of the bag: 15.3V
there are as many theories about minimum cell voltage as there are people on earth.
usual values are between 2.9 and 3.3V
I'm going for 3.3V because this applies to the whole pack and there is always one cell that falls behind a little bit. if the pack is treated as all cell were equal, the weakest cell gets stressed a lot and looses even more performance.
so, 4 times 3.3 equals 13.2V
that's my stage 2 value.
for stage 1 I guessed 3.5V per cell leading us to 14V.
I have no values for the load loss yet.
But I think these values are a good start.
I do recommend that you use a single cell voltage monitor.
they are cheap and make a lot of noise when they go off.
configure them at 3.3V so you have some reserve.
they are small and connect to the balancer plug of the battery.
if one cell drops below the preset voltage a loud alarm goes off. if you hear it: land! now!
this doesn't interfere with the naza's low voltage protection and you can use it as a second layer of protection in case the model is too far away for the alarm to be heard.
if it's in your budget, get some telemetry equipment to monitor the voltage in realtime from the ground.
ideally something that records the voltage over time and enables you to visualize the data. this makes it easy to see when your battery is about to give up.
a third layer of protection is your transmitter if it offers a countdown. I've discovered this on my Spekrum DX9. For each model, a run time can be set. while the throttle is above zero it counts down to zero, beeping at the last minute. the countdown stops if the throttle is in the 'off' zone and the TX assumes the motors are off and no (significant) power is used from the battery.
I hope this helps you a little. |
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