Estimate flight time given RX battery size and servos
12-09-2011, 09:27 AM
#51
RE: Estimate flight time given RX battery size and servos
And a back to the original question.
Q: How do I find out how many flights I can safely fly with my pack?
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A: The answer is different for just about every application. Factors like how you fly, what servo's you have, what the temperature is and what the type pack and it's relative overall condition is will all impact the number of flights you can safely fly with a full charge. A battery cycler can establish what the capacity of the pack is, and your ESV checks will reveal when it’s no longer safe to fly. To determine the amount of energy required to fly your plane just fully charge the pack and fly two or three of your routine flights (while checking between flights with an ESV to stay safe) and record the amount of time flown. You can then return the pack directly to the cycler and record the capacity remaining. Subtract that from the normal capacity of the pack to get the amount of capacity your flights used. Next, just divide the amount of capacity used by the number of minutes flown and you have the average amount of capacity consumed per minute of operation.
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Q: Ok, now that I know how long I can fly my pack, why keep checking with my loaded ESV?
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A: The value of doing a loaded ESV test before every flight becomes even more apparent when the number of safe flights count begins to materially change. Lets say my 'Divit Digger .90' is getting to the safe minimum loaded voltage after 3 flights when just a few months previously it averaged 5 flights. The big question now becomes ‘What's changed.. and why?'. Time to re-charge and cycle the battery to see if the pack is aging and needs replacement or if the charger's the culprit. If the pack and charger check out ok, what on board the aircraft is pulling all that juice? Most often I find a servo problem, either stalling at full transit (throttle setup needs re-adjusting, fairly common) or a condition developed with servo gears or control system linkages. Point is, because you had a data point to start with you were able to detect a material operational change and head off a problem before it swallowed an airplane.
*
Q: How do I find out how many flights I can safely fly with my pack?
*
A: The answer is different for just about every application. Factors like how you fly, what servo's you have, what the temperature is and what the type pack and it's relative overall condition is will all impact the number of flights you can safely fly with a full charge. A battery cycler can establish what the capacity of the pack is, and your ESV checks will reveal when it’s no longer safe to fly. To determine the amount of energy required to fly your plane just fully charge the pack and fly two or three of your routine flights (while checking between flights with an ESV to stay safe) and record the amount of time flown. You can then return the pack directly to the cycler and record the capacity remaining. Subtract that from the normal capacity of the pack to get the amount of capacity your flights used. Next, just divide the amount of capacity used by the number of minutes flown and you have the average amount of capacity consumed per minute of operation.
*
Q: Ok, now that I know how long I can fly my pack, why keep checking with my loaded ESV?
*
A: The value of doing a loaded ESV test before every flight becomes even more apparent when the number of safe flights count begins to materially change. Lets say my 'Divit Digger .90' is getting to the safe minimum loaded voltage after 3 flights when just a few months previously it averaged 5 flights. The big question now becomes ‘What's changed.. and why?'. Time to re-charge and cycle the battery to see if the pack is aging and needs replacement or if the charger's the culprit. If the pack and charger check out ok, what on board the aircraft is pulling all that juice? Most often I find a servo problem, either stalling at full transit (throttle setup needs re-adjusting, fairly common) or a condition developed with servo gears or control system linkages. Point is, because you had a data point to start with you were able to detect a material operational change and head off a problem before it swallowed an airplane.
*
12-09-2011, 02:31 PM
#52
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RE: Estimate flight time given RX battery size and servos
Nice point raptureboy.
mranga - Let us estimate your flying time based on your servo and battery data.
Total Average Servo Amp = 2 x 0.25 + 3 x 0.10 = 0.80 A
time = 1.0 Ah * 80% / 0.8 A = 1 hour or 60 minutes
Fully charge your battery and fully dicharge it with watt meter connected, make sure you got 1000mAh if not update my calculation.
After your first flight on a fully charge battery, discharge your battery remaining capacity with wattmeter connected and subtract that to fully charge capacity and you'll get mAh per flight. Divided by the first flying time in hours, you'll get actual average current for your plane.
If you fly 10 minutes per flight, you should get 6-flights per cycle.
mranga - Let us estimate your flying time based on your servo and battery data.
Total Average Servo Amp = 2 x 0.25 + 3 x 0.10 = 0.80 A
time = 1.0 Ah * 80% / 0.8 A = 1 hour or 60 minutes
Fully charge your battery and fully dicharge it with watt meter connected, make sure you got 1000mAh if not update my calculation.
After your first flight on a fully charge battery, discharge your battery remaining capacity with wattmeter connected and subtract that to fully charge capacity and you'll get mAh per flight. Divided by the first flying time in hours, you'll get actual average current for your plane.
If you fly 10 minutes per flight, you should get 6-flights per cycle.
