Aeronavics / Droidworx Sky Jib X4 Ti QR Flight Times

[Area21]

Just joined form to get help - please see my joining post Adrian Appleyard so you have a rounded view of who I am. Question is about flight times and really getting bogged down and hope someone out there can help.
Sky Jib X4 Ti QR. Fitted with Canon 5D Mk 2. DJI Z15 Gimbal. Flying weight 10,6kg. T Motors MN3515-15 Kv 400. 8 x Props 16 x 5.4. 2 lipos Gens Ace 10000. 25/50c 22.2 v S6. DJI A2 controller. Futaba 14sg. and Futaba T8J for Gimbal. A2 assistant voltage set to 22v 1st warning and 21v 2nd warning. With a pair of fully charged batteries 25.2 v that have been charged 12 times (so I am informed) . I am getting 4 mins flight time hovering before the 22v 1st warning activates. Weather temp 12 deg C. Re-charge batteries and it looks like I am only using 20% of the battery capacity! This is clearly not right and I need to know whether it's the A2 voltage set up that's wrong, or the lipo batteries, or size of propellers or any thing else ?
Appreciate any help and advice.
Adrian.

 

[gael]

I only use the voltage on the Iosd. With U5, zenmuse gh4 and 2 x 10000, I have 10-12 mn. Go to ground at 21,7.

 

[Area21]

I only use the voltage on the Iosd. With U5, zenmuse gh4 and 2 x 10000, I have 10-12 mn. Go to ground at 21,7.

Is this the telemetry voltage back from the A2 as seen on the ground station monitor or are you using some other form of telemetry ?

I was considering turning off the low voltage actions and leaving the warning lights only active. Then fly with a full set of batteries for 4 mins. Land and check battery voltage and cell voltage after 30 seconds. If the power remaining is healthy I would fly (hover) again for 1 min and repeat the tests. Whilst noting the ground station voltage. I suspect I am being a little over cautious due to the cost of the outfit.
Appreciate your help.
Adrian.

 

[Hexacrafter]

Apple....
You need to look at the mah used..... not the voltage or voltage under load....
The voltage will drop immediately under load, and slowly drop & hit a plateau...and at the end drop suddenly...
The key is to figure out what flight time corresponds with 75% use in Mah. And what Voltage under load corresponds with this...
What Charger are you using? Are you sure you are fully charging... putting back the full mah?
When you charge the batteries, how many mah are you putting back in?
Each 10,000 mah battery would take 7,500 mah on recharge if you are landing with 25% in reserve....
My bet is that your not fully charging your batteries or are using only 4000 mah....

 

[Area21]

Apple....
You need to look at the mah used..... not the voltage or voltage under load....
The voltage will drop immediately under load, and slowly drop & hit a plateau...and at the end drop suddenly...
The key is to figure out what flight time corresponds with 75% use in Mah. And what Voltage under load corresponds with this...
What Charger are you using? Are you sure you are fully charging... putting back the full mah?
When you charge the batteries, how many mah are you putting back in?
Each 10,000 mah battery would take 7,500 mah on recharge if you are landing with 25% in reserve....
My bet is that your not fully charging your batteries or are using only 4000 mah....

Answer: I am using a Power Lab 6 100watt charger powered by a EFuel 1200watt 50amp power amp. I charge the batteries in pairs set to Auto balanced charge. When starting a recent charge after a 4 min flight time the battery power indicated the batteries were at 80%. Cells were reading 3.9 to 4.01. When it had reached 100% it had put back in the batteries 2269 mAh. All cells were at 4.2 volts. This to me confirmed I had after 4 mins flight time only used 20% of the batteries available power with A2 voltage 1st warning coming in at 22 v. So by applying the 80/20 rule (yours is 75/25) I should be able to get a total flight time of about 12 mins. But just dare not try this all in one go with all the voltage safety systems turned off. I had a wookong M red light situation with my F550 a while ago and it simply descended quite fast and experienced a very lucky landing. Just don't want to try this with 10,6kg skyjib x4.

I am away now for a week, so when I get back I will carryout some tests taking your advice. Test will be: Turn off physical warning voltage system but leave warning lights active. On a fully charged pair of batteries to hover the drone for 4 mins. Land remove batteries and place on charge and note the power percentage remaining but not to charge batteries. Refit batteries and fly again for 1 or 2 mins. Land and run the same battery tests. Repeat until the battery percentage with the charger shows 20% remaining. If I also take voltage readings from the ground station I should have a far better idea as to whats happening. I may even fit a pair of noisy lipo low voltage triggers and see what they read. Never had this complex problem before with any of my helicopters or drones and thought and still think it may be effected by the type of props, running top and bottom props at same speed and quality of lipo batteries. I also prefer the Wookong M low voltage system as this gives both unloaded and loaded voltages where as the A2 is only unloaded.
If you or anyone can offer any further help and advice it will be really appreciated.

 

[Carapau]

Adrian, with the iOSD all it takes is a momentary drop in voltage to trigger the alarms. The momentary drop could be caused by a very short blip in the motors as the A2 is trying to hold height etc or to start a climb etc. The advice on looking at you MAH used is sound. You shouldn't have a massive voltage drop though with that set up but keep an eye on it as a large voltage drop can be the sign of high internal resistance of the batteries- a sign that they are aging and need replacing.

 

[Area21]

Adrian, with the iOSD all it takes is a momentary drop in voltage to trigger the alarms. The momentary drop could be caused by a very short blip in the motors as the A2 is trying to hold height etc or to start a climb etc. The advice on looking at you MAH used is sound. You shouldn't have a massive voltage drop though with that set up but keep an eye on it as a large voltage drop can be the sign of high internal resistance of the batteries- a sign that they are aging and need replacing.

Many thanks for your advice. Hope to carryout further tests this week so will report back on my findings which I hope will help others.

 

[Area21]

Just completed 2 half days of testing in winds gusting 20 mph in the Uk. Not ideal but flyable with a heavyweight craft.
Tests were with one pair of 10amp 22.2 volt Gens which are suspect to degrading and two pairs of 8amp 22.2 volt Tattu batteries almost new I borrowed.
Set A2 voltage actions to ' warn only' with 1st action set at 21 volts and 2nd action set at 20 volts. Note the A2 tries and sets these to 22 and 21 volts respectively which was partially influencing my previous 4 mins flight times.
Instead of auto calibrating the battery voltage I set this manually after taking voltage readings from each battery.
Flight tests with the 8amp Tattu batteries gave me 10 mins until I hit 21 volts and 1st warning. Landing and resting batteries for 5 mins these were set to charge and its showed they had been depleted by 74% leaving 26%. These were the same with both pairs of batteries. So well in the 80 / 20 rule. Then recharged these to 100% and ran the same tests again. All with same results.
Sames tests with the suspect pair of Gens and got the same times of 10 mins but the batteries showed 80% depleted. These would not recharge higher than 94%. Ran this test twice with same results.
Conclusions:
With the 8amp Tattu batteries I was pleased with the 10 mins flight times with my 10,6kg Skyjib X4 Ti-QR and I estimated I would have 1 or 2 additional minutes before the 2nd warning of 20 volts would have triggered. (these are loaded voltages)
With the suspected 10amp pair of Gens batteries their performance was less than the 8amp Tattu batteries although they are 0.3kg heavier each, but the extra 2amps per battery this was not shown as extra flight minutes.
Recommendations. Buy 3 new pairs of 10amp 22.2 volt Tattu batteries. Leave A2 voltage setting as 21v and 20v as is. Don't set the seconds warning to auto land as is. Terminate the 10amp Gens batteries from further flying.
Good outcome I believe.

Secondary question:
The gens have XT60 connectors and thinking of moving to XT90 or EC5 - advice anyone ?