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Run time

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Old 09-22-2016, 06:14 PM
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JGalt
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Default Run time

Hi, I am an old fuel R/Cer getting back into the hobby with an electric glider. The R/C glider ESC & battery powers the motor and radio receiver/servos. The instructions say full power should provide about 6 or so minutes of motor time but my question is will there still be some battery power to land the plane? If so, how will I determine how much flight time I still have?
Many thanks in advance for advice and assistance.
By the way, I tried to post this to R/C gliders but nothing happened. On the left side looks like a chain icon so perhaps that link doesn't work.
Thanks!
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Old 09-22-2016, 06:21 PM
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JGalt
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I just found Ed Anderson's book and the answer. The motor slows or stops but there is still enough power to land.
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Old 09-23-2016, 04:08 PM
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Quorneng
 
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JGalt
Yes, its all down to the motor's Electronic Speed Controller (ESC). It not only controls the motor speed according to the throttle signal sent by the transmitter but with a completely separate circuit it provides a regulated constant voltage (5V) to power the receiver and the servos.

The ESC senses the battery input voltage and at a predetermined level, the Low Voltage Cutoff (LVC) which depends on the type and number of cells in the battery, the power will be cut to the motor but the 5V supply remains. There will several minutes of power left in the battery to land the plane but remember the plane will be gliding!
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Old 09-25-2016, 06:22 AM
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da Rock
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Originally Posted by JGalt View Post
I just found Ed Anderson's book and the answer. The motor slows or stops but there is still enough power to land.
Back when a couple of us glow fuel guys decided to do some electric and see what it's all about, we took that advice. All of us ruined batteries.

An awful lot of ESCs have a voltage setting to protect the batteries they use for that low voltage warning behavior. The problem with it is modelers who rely on it get sloppy and find their model way out over the corn one day when the motor quits. So they pull the throttle to zero to reset. And wind up giving it throttle to come on home. And home isn't real close. And that night they notice they've got another puffed up battery. One that holds less charge now. And shows up with an unbalanced or bad cell.

We quit doing that a couple of years ago and haven't puffed a battery since. You need to get a wattmeter that also checks capacity and work out a safe and sensible time limit for each model.

It looks like you haven't come back since the 22nd.
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Old 09-26-2016, 05:41 PM
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JGalt
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Thanks all for the good advice. Getting back to the hobby after 30 years is a real cultrue shock! I appreciate your help.
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