In this log (122) the hover current is right around what would be expected with that kit of parts at that weight.
Itās basically phantom 2 spec motors, so I would have expected to see a little longer on a 5000 3s, even at 1.4kg it should get at least 10 minutes. Assuming his current meter is accurate, then for some reason its drawing a lot more power than it should, the only possibilities I can see for that is the landing feet are blocking the propeller downdraft or the propellers are too big and are overloading the motors.
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Sounds right. Flexi props, big air obstructers and and the prop ātraining guardsā could add up. The initial battery sag is kind of high.
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Thanks for all the input guys!
I have tested the current sensor against a Tektronix A622 current probe.
the values are not very accurate from the Fc sensor.
When armed Fc will show 0.0A but the current clamp shows 2.1A.
I have tried to calibrate it as close as possible but it seems like it has a non linear curve and its hard to really know without a teather or other device to hold the copter.
Motors and frame are an old Acstec Pelican with Cube Orange to replace the old FC.
I will try and acquire some additional props and test without guards and feet. ( for indoors these are kind of critical but would be a good exercise to understand the battery issues.
I will also try and get a tattu or GNB battery ( I do agree that the gold bat 40C rating is optimistic.)
Thanks!
The current sensors are inaccurate at low current levels so they are difficult to calibrate without something like a high current charger.
Interesting I will try and put this on the bench with my load tester.
Iām surprised by the non-linearity. I will try and graph it here.
The easiest and most popular way to calibrate the current sensor is to use logged mah vs re-charged mah and re-factor the Amp/volt value ratiometrically. Itās simple and plenty good enough for all needs. Itās all I ever use and I have a decent bench supply and meters. Waste of time to use them IMO.
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@dkemxr So the Current sensor is calibrate as per those instructions. Its close but clearly the sensor is not accurate at low currents as the arm spin is shown as 0.0A
I removed the āLanding Feetā and current was reduced by ~%25!
I will try without the prop guards and see if there is further improvement ( but they will go back on for indoor flights)
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Yes, thatās right. But itās good enough for the typical purpose of measuring current. You can try to monkey around with the amp offset but in the end itās not really significant.