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Old Yesterday, 08:28 PM
bryansifsof44's Avatar
United States, AK, Anchorage
Joined Oct 2011
4,546 Posts
I use a switch the same way Liberty does... I get off the throttle for 3-4 seconds so voltage recovers. It doesn't recover fully, but recovers about 95% of the resting voltage in that time, so it's close. Problem with setting up a alarm to land to is their is such a difference in sag voltage between different quality, older and new batteries. If you set the alarm for your weaker batts, your good batts run the risk of getting over discharged. If you set for your stronger batts, you prematurely land your weaker batts. This is why I use the method above.
However I set a alarm for 3.2 per cell so it will let me know if I am having a problem. Saved me before when I mistakingly put in a discharged battery and another time when I dropped a cell in a 12s setup. I was able to nurse it around for a landing. Another good reason to run a 12s setup when you can... 6, 8 and maybe 10s would of hit cutoff if you have it setup.
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Old Yesterday, 09:18 PM
3D? I only got two thumbs!
United States, MA
Joined Jul 2012
1,137 Posts
I set up mine the same was as bryansifsof44 after reading his description a while back. Very nice, just poke the button with the throttle down and get the voltage. I use the timer as the main control (speaks the time left at 1 minute intervals), if I've been being extra aggressive I poke the voltage readout button before the timer goes off just to check. If I think I've been less aggressive than usual I poke the button when the timer goes off to see if I can squeak in another minute or so. Or if there's someone trying to land and needing a couple go arounds when my timer goes off I check the voltage to see how urgently I need to land and/or conserve the juice.
As you guys say it's mostly judgement, with a little data added to improve or confirm the result.
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Old Today, 12:41 AM
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United States, MA, Lowell
Joined May 2004
827 Posts
Quote:
Originally Posted by bryansifsof44 View Post
I discharge to 3.75 per cell resting voltage and always put about the same mAh back into the pack. No matter how fast I discharge the pack.

That's what I was hoping. So im definitely getting that efuel gauge.
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Old Today, 12:56 AM
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United States, MA, Lowell
Joined May 2004
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I was the OP of this little sub-thread. I never liked the idea of using voltage to determine when the battery's empty. I feel like for the last few minutes of the flight the alarm would be going off every time I hit WOT. And the 14SG can't speak the telemetry data and I'm not going to look down at the TX to check the voltage.

The thread below is for an efuel gauge they would count the mah used. It would only alarm when the last mah is exhausted.

http://www.rcgroups.com/forums/showthread.php?t=1919818
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Old Today, 01:22 AM
bryansifsof44's Avatar
United States, AK, Anchorage
Joined Oct 2011
4,546 Posts
Power Systems for Extreme Flight Fanatics!

Neil, that is exactly the reason I don't use a alarm and do as I describe in my post above. Would I rather have a mAh counter? Heck ya, but this works great and never have a issue. I posted a number of times in the DX8/DX9 threads that a capacity sensor (mAh counter) would be a helpful addition to my specky. Others have them, but haven't got my request yet and I'm not going to switch radios just to get the counter.
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Old Today, 06:16 AM
Byron C
3DeltaFly's Avatar
United States, TN, Knoxville
Joined Apr 2011
713 Posts
Combined mAH and voltage telemetry

mAH telemetry is something I couldn't do without, now that I've gotten a good taste of the technology and have been using it for a full season (60" planes and up).

I'm using both mAH and voltage telem combined to keep tabs on the drive packs. Here's my standard 3D plane telem setup:

1) Drive system *initialization* low voltage alarm, sounds if one tries to fly a less than fully charged pack.
2) mAH alarm for 75% spent capacity.
3) mAH nagging repeating alarm for 80% spent capacity.
4) Low voltage alarm for a serious voltage sag event should any pack's voltage sag below a user specified level.

My current TX is the Jeti Duplex DS-16, and there is virtually no limit to what the alarms can sound like; voice, musical, or even Morse code. Anything that can be recorded in an MP3 format. Not to mention that the TX is factory supplied with an array of various voice alarms too.

* The initialization drive pack voltage test functions via a logical switch; full down ELV + idle up (side paddle control) set to off. Before each flight I'll check that all control surfaces are working and going in the correct directions. The full down ELV + idle up set to off has worked out really well for my logical switch.
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Last edited by 3DeltaFly; Today at 06:30 AM.
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