S800 Noob with EMBARASSING Flight times WTF!

R

R6Media

Member
Seriously, these flight times are abysmal.

Here's my airframe:
Standard s800 kit with WKM and Z15 for Nex7 and fixed landing gear (no retracts).
iOSD MarkII, anti-vibration kit, 5.4gHz video downlink. pretty simple setup, nothing special and weighty

I've got 3 pairs of batterys running parallel.

2-6s Zippy compact 5800mAh (3.4 lbs for the pair)
2-6s Zippy 5800 mAh (3.6 lbs pair)
2-6S Zippy 5000 mAh (3.6 lbs pair)

these were my options considering everything else I was looking at was out of stock and back ordered which seemed really strange to me. Who's buying all the LIPO up YO!!!!

anyway. after these times, I'm wondering if there was a reason noone was buying these.

I got 4:15 seconds out of my dual zippy compacts before my voltage readout said 22.2 (under load) and enjoyed a nice 12 inch hover auto death drop to the soft grass below. Seriously???
My second pair was even worse. The regular Zippy 5800's gave me only 3:33 before hitting 22.2 (under load)...
Oddly the 5000mAH pair, 1600total mAh less, gave me my best time of 4:35.

WOW!
Also strange to me is how much battery is actually left. 44% on both standard Zippys and 52% left on the compact Zippys. and my resting voltage immediately goes back to over 23. at idle.

I must be missing something. Am I just too heavy even though its a pretty standard rig or do these batteries just suck this badly???? The flights were super casual in no wind conditions. basic hovering and gentle forward flight. outside temps in the mid 70's
Obviously the Zen is sharing the load but come on!

Any thoughts before I throw money at more expensive LIPO that will probably just give me the same results?

Other than that.... this thing flies awesome.... so fun! and I don't think 10 minute flight times are unreasonable to ask with a full load for but what do I have to do to get there?

These were her maiden flights. Makes me wonder if there is some kind of "break in" and things will get significantly better. Heres hoping.

Thanks.



-Tim
 
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D

Dewster

Member
Whew! All of the advances in technology mean nothing without a good and steady power supply. My Y6 crashed when my old lipos gave up on me. At first I thought the crash was due to DJI's 2nd level voltage protection. I tested my lipos on a test quad without the voltage monitor on and got the same drop of death. Old, worn out lipos. :(

Heres the vid of my Y6 drop of death/dismemberment:

http://youtu.be/DaCp1USGAGM

Lessons learned:

label and track the flight times of your batteries, especially if you run them in parallel

lipos have reduced flight time with age - treat them right to maximize the use of your batteries

keep your flight batteries separate from powering your video transmitter and possibly a hungry camera gimbal

keep the weight of your craft low - adding more batteries will not necessarily increase flight times - there's a threshold

use 3-5 dollar lipo alarm and trust it

Your lipos will drop in voltage under load - the more weight and systems you have running off of it, the more the volts will drop when your craft is in the air. Your lipos will recover when the load is taken off of the battery (after your craft lands). This is factored in DJI voltage protection. You have to make sure you use the right voltage numbers when doing so. These numbers will change with the weight/configuration of your craft.

I think running more than 2 lipos in parallel (at your stated weight) is just too much. The lipos just can't supply the demand. I think you have a good balance between weight and power consumption when you are able to safely use 80 percent of your battery. 44% tells me that your craft is too heavy.

Play it safe. These crafts are expensive and weigh too much to be falling out of the sky.
 

TAPPEDOUT

TAPPEDOUT

Member
Probably better results with GenAce packs. Use larger connectors and check solder joints. Progressive RC's ESR Meter is nice for checking internal resistance of pack and individual cells. It's good to use to monitor health of pack.
 

Benjamin Kenobi

Benjamin Kenobi

Easy? You call that easy?
I just think its your voltage protection kicking in too early. Lower it as 22.2v seems a little high to me (under load). I have mine at 21V. Remember, the voltage protection is for emergencies only. Use a timer and a good charger to measure your lipos. If you have a current sensor on your OSD even better!

New lipos do need breaking in. The first ten flights take it slow.
 

F

fj_montilla

Member
I'm using the Max Amps 10900 mah for my S800 (similar setup as yours). They're expensive but juicy. I do 10 min flights at a time. These can go for 15 min, but why chance it?
I had something similar happen with a smaller hex I have using naza. I was getting flashing red lights from my LED within seconds of take off. My solution; turn off power monitoring in your assistant software.
Do a test flight with your radio's chronometer turned on. Keep the hex close to the ground and land as soon as you see the strange wobbles that lead to a dead battery. Watch your time stamp. Say you flew 10 min, subtract a minutes and these 9 min could be your safe flight time.
 


R

R6Media

Member
Hey guys thanks for all the thoughts.

Dewster: Actually the Lipos are all brand new, these were they're first flights. As far as external voltage alarms I have them ($5 from hobbyking) but I can't hear them over the ship. I am happy to take other suggestions as far as those go as I believe they are crucial.

TAPPEDOUT: I've got EC5's on them but you make me wonder.... Not that this is the case since i think my connections are ok but IF the solder joints were cold, how would that affect my power output?

Benjamin Kenobi: Yeah I know that the drop at 22.2 was from my voltage protection. You're probably right, I might be being a little conservative. Thanks for the mention about break-in I did forget about that actually. As far as it being for emergencies, the way this thing drops looks like it will create a whole other emergency! ha. its pretty fast. Nothing like my unloaded 550 that does has a nice gradual descent rate with no response to increased throttle.

fj_montilla: yeah i get the flashing red on my Naza all the time on my 550 but i disregard it since i track the timing I've been able to safely get on those 3S's. Thanks for the maxamps tip.

ProPilotWannaBe: Hey Tim, yeah those weren't available when i was battery shopping but helpful to know what you're using too. Not that it would have mattered but i couldn't bring myself to spend $1200 on thunder power like Charlie talked about. They may love them but I've seen plenty of mixed reviews... just like anythin else.

So I pose simply 2 more questions:
How would the solder joints affect the output?
What are you guys setting your voltage protection at if you're using it at all?

-Tim
 

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ProPilotWannaBe

Member
I have my first level voltage set to 22.2V loaded. As for the second level protection, and because of the scare Dewster gave me a couple of weeks ago, I set it way out of the way like at 20V.
But I have to BlueCell voltage alarms from Amazon that are set to 3.5V for one, and 3.4V for the other. I can hear those things over the S800 prop noise at 100 yards out and I start wrapping up what I'm shooting when the first one kicks in, and start heading home. If the second one kicks in, I drop what I'm doing and book it home. The last time I measured what I put back in under this scenario I was putting back in around 80% which is a good measure for me.
I also monitor my timer and the loaded voltage iOSD overlay so that I have a feel for how much time I have left to decide if I have enough time for my next shot(s) planned.
 

Droider

Droider

Drone Enthusiast
Flying muliple packs in parallel is not the best idea. I fly two packs always but would never link more. The reason your machine has short flight times is because you cannot get the energy out of the packs pure and simple.

Check you voltage drop from start up to hover. I ideally it should only be about .5 to .7 of a volt.. bet yours is up much higher than that. The smaller the pack the higher the C rating needs to be to deliver the amps a S800 needs. Go buy yourself a couple of 6000mha 5c rated minimum like the Gensace and your problem will go away.

As for cold joints and multiple connections these add resistance into the system slowing the flow of energy, just like crimping your garden hose you can all the pressure in the world but the flow is nothing, relece the crimp (the resistance and away you go with a squirt to be proud off...

Battery alarms are a no brainer get them now and save your self a whole load of grief... trust me from one who has been there!

Dave
 

Benjamin Kenobi

Benjamin Kenobi

Easy? You call that easy?
Ah, as these were your lipos first flights then expect half the time. They need a gentle flight at least the first couple if times. I use 2xGensAce 5000mah and get a comfortable 10mins.

I think this is just a teething problem and it'll all settle down after you've cycled the lipos a few times. The altitude loss you noticed is the voltage protection. It moves the throttle mid point up to 90% so you can just about gain altitude at full throttle.

Lower your voltage protection values (think 3.4v per cell times 6) and run your lipos in with gentle short flights (half the expected time).

Cool?
 

OneStopRC

OneStopRC

Dirty Little Hucker
Just a thought, and I could not see this anywhere, so if I missed it, I apologize in advance..... Maybe your "C" rating is too low? and what are you connecting the two packs with? I have seen people on eBay making parallel connectors using 14 and 16 awg wire, if yours is the same, your loosing a lot of heat right at that point. Make your own with 10 awg or 8 awg if you can get the connectors to handle them.
 


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