Thread: Telemetry?
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Old 01-07-2017, 06:09 PM   #38 (permalink)
Thunder Fighter
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Join Date: Jul 2007
Location: Melb, Oz
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Thinking further on the filtered voltage method, there are other issues on top of what have already been described.

The voltage reading is dependant on load, even if integrated over time to average the load (and therefore voltage). So in a hard flight the average load (amps) will be higher and therefore give a larger voltage sag, even when averaged. So the alarm will be reached earlier than a very soft flight or low headspeed flight as the voltage drop under the lighter load will be much less so the result is more inconsistant than the capacity method.

So while the filter method can remove the spikes from a flight, it does not take into account light load versus high load conditions. For example if we set the alarm at a filtered 3.55v per cell, under a high load flight we might get a resting voltage of 3.75v saying there is a 0.2v voltage drop (1.2v on a 6s pack) from the load. With the same alarm set and a low headspeed flight which averages 1/2 of the amps we might get a 0.1v drop per cell under load (0.6v on a 6s pack) so leading to a resting voltage 3.65v per cell, which leaves a very different amount of capacity remaining.

With the capacity method it doesn't matter how I fly, or what headspeed I use so long as I start with a full pack, my resting voltage and capacity remaining in the pack is very consistent at the end of the flight. And it still doesn't stop me using specific voltage alarms to catch a bad cell or other issues.

//Dennis.
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