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What voltage on Tx is too low to fly safely?

Old 08-29-2011, 08:57 AM
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flymeaway
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Default What voltage on Tx is too low to fly safely?

I'm flying the Spectrum DX-7 with stock Tx pack (1,500 NiMh If I recall correctly). I generally stop flying when the indicator is just above half, or about 9.4 - 9.6 volts. I ask this question for a couple of reasons, one I simply don't know the answer, and two it always seems that I wish I could squeak just one more flight out for the day but choose not to based on the Tx falling below 9.8.

What voltage is too low to fly?

Thanks.
Old 08-29-2011, 09:58 AM
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Dangaras
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Default RE: What voltage on Tx is too low to fly safely?

The DX7 has a low battery beep. Ileft mine on overnight once and she was beeping away at a voltage close to 9.0 but Idont remember.

I got fedup of the performance and switched to a Turnigy 3 cell, 1800mAh, 5C LiFe pack and it will last a month of 20 -30 flights every week.. Fits perfectly.

It will sit at 10.4V fully charged, 10V after a few hours and stay there for 1 or 2 weeks, then drop to 9.9/9.8V for another week. Usually I charge the pack on my battery charger after it is at 9.8v for that last week.

http://www.hobbyking.com/hobbyking/s...4_TX_Pack.html
Old 08-29-2011, 12:08 PM
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Default RE: What voltage on Tx is too low to fly safely?


ORIGINAL: flymeaway

I'm flying the Spectrum DX-7 with stock Tx pack (1,500 NiMh If I recall correctly). I generally stop flying when the indicator is just above half, or about 9.4 - 9.6 volts. I ask this question for a couple of reasons, one I simply don't know the answer, and two it always seems that I wish I could squeak just one more flight out for the day but choose not to based on the Tx falling below 9.8.

What voltage is too low to fly?

Thanks.
About the only way you can know how much capacity is left in the battery is to put it on a cycler after you've had the transmitter on for awhile. That will tell you how much capacity is left in the battery. Transmitter meters and displays are for the most part worthless at telling you how much capacity is left in the battery. I would guess most people only use their transmitter batteries down to about half capacity based on meters. I see it all the time at the field when they stop flying when the display starts to fall a bit from what they consider normal.
Old 08-29-2011, 12:21 PM
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mmn
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Default RE: What voltage on Tx is too low to fly safely?


ORIGINAL: flymeaway

I'm flying the Spectrum DX-7 with stock Tx pack (1,500 NiMh If I recall correctly). I generally stop flying when the indicator is just above half, or about 9.4 - 9.6 volts. I ask this question for a couple of reasons, one I simply don't know the answer, and two it always seems that I wish I could squeak just one more flight out for the day but choose not to based on the Tx falling below 9.8.

What voltage is too low to fly?

Thanks.
From page 106 of the DX7 manual:

"Do not fly below 9.0V on the transmitter. . ."

Regards
Michael
Old 08-29-2011, 02:22 PM
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GBR2
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Default RE: What voltage on Tx is too low to fly safely?

I think where you are stopping is perfectly fine. Remember, the nominal voltage of an 8 cell Tx pack is 9.6 volts. So once you get below this you are certainly on the downward slope. I wouldn't let the voltage get to or below 9v, once there the voltage usually drops like a rock. Also by allowing the voltage to get so low, you run the risk of causing damage to the CPU and a trip back to Horizon for repair.
Old 08-29-2011, 02:34 PM
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Default RE: What voltage on Tx is too low to fly safely?


ORIGINAL: mmn


ORIGINAL: flymeaway

I'm flying the Spectrum DX-7 with stock Tx pack (1,500 NiMh If I recall correctly). I generally stop flying when the indicator is just above half, or about 9.4 - 9.6 volts. I ask this question for a couple of reasons, one I simply don't know the answer, and two it always seems that I wish I could squeak just one more flight out for the day but choose not to based on the Tx falling below 9.8.

What voltage is too low to fly?

Thanks.
From page 106 of the DX7 manual:

''Do not fly below 9.0V on the transmitter. . .''

Regards
Michael
you can't read the manual, thats cheating!
I stop and recharge at 9.5 volts. but I'm very conservative. 9.0 volts is the warning beep on my 10X.
Old 08-29-2011, 04:15 PM
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mmn
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Default RE: What voltage on Tx is too low to fly safely?

ORIGINAL: Brian Dorff
you can't read the manual, thats cheating!
Funny!

[soapbox on]

I come from a [long] background in training and support. Often I would get questions from subordinates about things that were in the manual. I would tell them "when you've read the manual and either the answer isn't in there or you don't understand it, come back to me, but not until..."

We don't take the time to RTFM. We'd rather rely on those who do. Well, as we all know, everybody has opinions and some actually know what they're talking about. How do you know the difference?

I was so sure the OP's question was answered in there, I had to go see. Took about 30 secs to find it.

[soapbox off]

Let the flames begin...

Regards
Michael
Old 08-30-2011, 06:52 AM
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flymeaway
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Default RE: What voltage on Tx is too low to fly safely?


ORIGINAL: mmn

ORIGINAL: Brian Dorff
you can't read the manual, thats cheating!
Funny!

[soapbox on]

I come from a [long] background in training and support. Often I would get questions from subordinates about things that were in the manual. I would tell them ''when you've read the manual and either the answer isn't in there or you don't understand it, come back to me, but not until...''

We don't take the time to RTFM. We'd rather rely on those who do. Well, as we all know, everybody has opinions and some actually know what they're talking about. How do you know the difference?

I was so sure the OP's question was answered in there, I had to go see. Took about 30 secs to find it.

[soapbox off]

Let the flames begin...

Regards
Michael

Here's your FLAMES!!!!

Just kidding.

Funny thing about manuals, I looked in the TOC, looked through the chapters where I thought this info should be... nothing. Maybe I'm an idiot, maybe I'm lazy but I didn't find it. The other side of that coin is that I can usually count on not only specific information to come back on a chat site regarding my question, but many times can net other decent information to think on, such as the information in posts 2 & 3.

Thanks for finding that in the manual though, I appreciate your time.
Old 08-30-2011, 11:03 AM
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Rodney
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Default RE: What voltage on Tx is too low to fly safely?

It is not hard to find out for yourself in a manner that guarantees accuracy. Just fully charge your transmitter then note the time and turn on the transmitter. Let it run until the low voltage alarm goes off. At that time turn on a known working receiver and see if the transmitter still operates the system (it will). and note the time and voltage. Now you know how many hours you can safely run your transmitter and have reliable operation. Chances are it will be quite a bit longer than you thought it would be. Now you have actual known data and do not have to take any ones word for it. Now, as your battery ages, the time will decrease but the voltage at the point you should recharge will not, just now monitor the voltage and you will know when to stop flying until you recharge.
Old 08-30-2011, 12:34 PM
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mmn
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Default RE: What voltage on Tx is too low to fly safely?


ORIGINAL: Rodney

It is not hard to find out for yourself in a manner that guarantees accuracy. Just fully charge your transmitter then note the time and turn on the transmitter. Let it run until the low voltage alarm goes off. At that time turn on a known working receiver and see if the transmitter still operates the system (it will). and note the time and voltage. Now you know how many hours you can safely run your transmitter and have reliable operation. Chances are it will be quite a bit longer than you thought it would be. Now you have actual known data and do not have to take any ones word for it. Now, as your battery ages, the time will decrease but the voltage at the point you should recharge will not, just now monitor the voltage and you will know when to stop flying until you recharge.
You might get a visual on the little bar that way, but you can't rely on the time because the transmitter is sitting there idle. It won't use as much current as it does when you're turning it off and on, changing planes, and moving the sticks.

There's a little vertical bar on the horizontal voltage bar. Don't recall what voltage that is, but I stop if I get anywhere near that. Figure it's there for a reason. Just not sure what.

Regards
Michael
Old 08-31-2011, 06:10 AM
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Rodney
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Default RE: What voltage on Tx is too low to fly safely?


ORIGINAL: mmn


ORIGINAL: Rodney

It is not hard to find out for yourself in a manner that guarantees accuracy. Just fully charge your transmitter then note the time and turn on the transmitter. Let it run until the low voltage alarm goes off. At that time turn on a known working receiver and see if the transmitter still operates the system (it will). and note the time and voltage. Now you know how many hours you can safely run your transmitter and have reliable operation. Chances are it will be quite a bit longer than you thought it would be. Now you have actual known data and do not have to take any ones word for it. Now, as your battery ages, the time will decrease but the voltage at the point you should recharge will not, just now monitor the voltage and you will know when to stop flying until you recharge.
You might get a visual on the little bar that way, but you can't rely on the time because the transmitter is sitting there idle. It won't use as much current as it does when you're turning it off and on, changing planes, and moving the sticks.

VERY WRONG, transmitter current is a constant regardless of what you are doing with the sticks. The current drain stays constant under all conditions.

There's a little vertical bar on the horizontal voltage bar. Don't recall what voltage that is, but I stop if I get anywhere near that. Figure it's there for a reason. Just not sure what.

Regards
Michael

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