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Old Sep 08, 2014, 07:20 AM
NTX Helidillos
tonkajeep34's Avatar
USA, TX, McKinney
Joined Sep 2009
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if you stopped at 3.8 you only took the battery to 50%. You still have more juice left just don't take the packs down past 80%. 8 min for half way is pretty good!
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Old Sep 08, 2014, 03:21 PM
Rchelistuff
Romania, AR, Arad
Joined Nov 2012
558 Posts
Hi Tonkajeep
3.8v/cell is the lowest you should go without risking a damage to the li-pos.
I went one time all the way down (forgot it connected to my VTX) and the li-po had ~3.5 or so and all swallowed and off balanced on one cell...
I guess maybe down to 3.70 after landing since the cells will go back maybe 0.5v after unplugging( no more current draining).
My 2 cent
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Old Sep 08, 2014, 03:26 PM
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Quote:
Originally Posted by tonkajeep34 View Post
if you stopped at 3.8 you only took the battery to 50%. You still have more juice left just don't take the packs down past 80%. 8 min for half way is pretty good!
No, you are 100% wrong on that, your advice is risking his batteries.

3.8v (multiplied by 3 = 11.4v) puts him at 20% remaining. That's exactly where he should stop.

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Old Sep 08, 2014, 03:29 PM
Rchelistuff
Romania, AR, Arad
Joined Nov 2012
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Originally Posted by mysql101 View Post
No, you are 100% wrong. on that, your advice is risking his batteries.

3.8v (multiplied by 3 = 11.4v) puts him at 20% remaining. That's exactly where he should stop.

Tx for confirming what I already knew and said just before
Yeap...3.8 (ideally) or 3.7 under load is the lowest one should go...below the batts will heat up, swollen and eventually puff
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Old Sep 08, 2014, 03:32 PM
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I don't think 3.7 is a hard and fast rule for under load: On my 250, it eats barely .2v at hover, on my hex it can eat many times that.

My understanding is where the battery sits at idle after you land is important, so I adjust my cutoff voltage based on how much the copter skews the number while hovering.
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Old Sep 08, 2014, 03:41 PM
Team WarpSquad
United States, PA, Doylestown
Joined Jan 2014
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Quote:
Originally Posted by mysql101 View Post
I don't think 3.7 is a hard and fast rule for under load: On my 250, it eats barely .2v at hover, on my hex it can eat many times that.

My understanding is where the battery sits at idle after you land is important, so I adjust my cutoff voltage based on how much the copter skews the number while hovering.
Exactly and I have found that it depends on what battery, brand, capacity, C rating you use. Example:
WQ200 with Rhino 1050mAh, 40C battery: Hover Voltage of 3.3V per cell recovers to 3.7V per cell and is an 80% discharge by the amount put back in when charging.
Same quad but a NanoTech 1000mAh, 45-90C battery: Hover Voltage of 3.3V per cell is way Over Discharged. For this battery a hover Voltage of 3.4V per cell is about 80% discharged. and a Hover Voltage of 3.5V per cell is Half Discharged.

So you must learn what Voltage during hover is less than 80% discharged then be sure the land before that point.
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Old Sep 08, 2014, 03:49 PM
NTX Helidillos
tonkajeep34's Avatar
USA, TX, McKinney
Joined Sep 2009
1,525 Posts
Yeah i think we're all on a different page here. 3.8v per cell is storage voltage. If that's what the pack is at after the flight he still has a lot of runtime left. But like waltr said it will depend on his packs.

You can run lipos down to 3.3v per cell without issue. But you then have to calculate the MAH put back in. So if you have 4000mAH packs you don't ever want to put back in more than 3200mah (and that will degrade over the life of the pack)

If you watch a pack under load it's very hard to tell when to stop as not all packs are the same and lipos have a very flat discharge curve. So you may not get a warning or see a voltage drop when you're under 80%. The best thing to do then is use voltage per cell and consumption to determine how long you can run the battery. Or, just set your alarm to 3.4 or 3.5 and you should not ever have to worry. For instance most LVA's are set at 3.3-5v per cell.
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Old Sep 08, 2014, 07:12 PM
'FPV'er...not a "LOS'er
Vantasstic's Avatar
Las Vegas, NV
Joined Sep 2003
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Ah common guys. Most the batteries we use aren't expensive anyway. So use and abuse your pack and just buy some new ones for $30 when the old ones just can't hang any more. Of course, if you're using $$$ batteries (like Thunder Power) then you are risking more $$$ by abusing the batteries.
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Old Sep 08, 2014, 09:55 PM
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Joined Jul 2014
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Maidened her today. All went well. Using a cc3d board, sunnysky 2212 980kv motors and Lumenier 4s 3300mah bats. Got a solid ten minutes(lots of hovering) out of her. AUW with a mobius is 1400g. No fpv gear......yet
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Old Sep 09, 2014, 09:12 AM
Learning to crash
Tom T's Avatar
United States, IN, Indianapolis
Joined May 2014
306 Posts
So I'm sitting here thinking (oh lordy) of trying some 10" props on my Flip. Currently running the HQ9045's, SS2212-13-980 motors, 4s 4200 Lumenier packs, and Lumeniers 30A simonk ESC's. Can I run 10" props and gain any flight times? Or would the amp draw be too much? The most I've seen on the OSD is a 50 amp draw on a punch out. I really just fly smooth circuits with an occasional punch out, and no tree racing with it. I'm already getting 12 minutes of just smooth flying and even more just hovering around. Would I see an advantage or not? Prop recommendations?
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Old Sep 09, 2014, 05:31 PM
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Kauai
Joined Jan 2011
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I've been using the Eagletree Vector to figure out what's most efficient by changing blades,hover,check amp draw and repeat.Also changing battery packs from 3s to 6s,interesting stuff( not on a Flip).At hover 6s had the lowest hover amp draw,but highest peak amps7/55.At 4s hover was at 12 amps.Changing prop sizes changes it all again.The Vector makes it easy.
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Old Sep 13, 2014, 12:39 PM
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Any of you guys ever have any experience with Buddyrc.com. I've bought a ton of stuff from them in the past year and have never needed any customer service until now. I ordered 4 sunnysky motors and one of them was machined poorly and the prop adapter would not fit. To save time for my build I just ordered a fifth motor to move things along.

Fifth motor was fine but I'm trying to get a response out of these people concerning the bad motor. Multiple emails and calls to a answering machine but no one has replied to anything. I'm not happy and will buy nothing from them again . Too bad because i liked the Glacier bats. Guess its Lumeniers from here on out>
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Old Sep 13, 2014, 12:58 PM
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I've heard more than a few people say the same thing about BuddyRc .Ive not needed to talk with them on any issue but looks like their service isn't quite there.Most stuff BuddyRc carries is now available from other venders with service!
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Old Sep 13, 2014, 12:58 PM
Too Many Thread Subscriptions
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Joined Jul 2012
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man, BuddyRC is great, ive spoke to Gary multiple time and he helps out. maybe you've reached them during a busy time.. good luck
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Old Sep 13, 2014, 06:34 PM
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Originally Posted by TheFernMan View Post
man, BuddyRC is great, ive spoke to Gary multiple time and he helps out. maybe you've reached them during a busy time.. good luck
Well I'll keep trying, but If he does not contact me soon I'm going to start spreading the word around the web some more
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