How far can battery discharge and hover pass 0% charge

[SuperPete]

This is just a test, it's not something that should be done every flight, it's for emergency situation only when you coming home and just not quite making it, so you know how much more you have in it.
Enjoy

 

[Former Member]

OP, just curious if you know what your battery voltages were after it got down to zero?

Definitely dont try this at home or when flying

 

[SuperPete]

If you watch the video there are screen recording of it, you can see it. Sorry can't remember now.
From many years of RC experience and years of using LiPo battery back in the day, lowest lipo can take before no return point is around 2.4-2.6V, so I think DJI programmed some safety feature here not to even come close to that point.
Back in the RC days I was flying ALIGN helicopters, we had to program speed controller ESC to lowest discharge rate and lowest setting there was 2.4V/per cell, I was always had my at 2.6, hundreds of charges on the lipo packs, never issue.

 

[Former Member]

Looks like the last screen shot you showed was 3.2 volts per cell at zero % battery.

I too came from electric helis, owned every Trex heli ever built, plus all type of cars trucks and boats. I have never known anyone to allow their batteries to drop below 3.0 volts per cell, even under load, but I guess you knew what you were doing.

Did you have it set that low because you were doing 3d? Almost every ESC made has their soft low voltage cutoff set at 3.3 volts per cell and the hard cut off set at 3 volts per cell. With many electric models that rely on the main battery pack to supply power to the servos, the servos will start to lose power when the LVC threshold is near, so that all power can be diverted to the main thrust motors. I guess you were using a pack just for use on the servos, receiver and gyro? You must have alot of practice doing autorotations, letting your flight pack get that low. Unfortunately, quadcopters dont autorotate very well. Motors stop when voltage stops, then you are flying a rock.

 

[SuperPete]

I hear you.
I had trex 600E, 500, 450 and baby 250.
Good old days.

I set battery low because I wanted to get most of the lying, once alarm go off at your 12 min of flight you know you have arox 20% left, with coming back home and landing down to 10% batt. at that point I was about 3 volt /cell.
2.6 was ESC shut down, I knew last few min I wasn't not doing hard core 3D it was more like coming back and landing, cool down process. that's why I did that.
Also if you had goof BEC it will do good job volt regulating and keep power nice a steady.

Anyway, good old days

 

[Kilrah]

Do not take that as anything more than curiosity, it is highly variable based on how good the current calibration state of the charge meter of a particular battery is, and can go the other way too.

 

[Former Member]

I hear you.
I had trex 600E, 500, 450 and baby 250.
Good old days.

I set battery low because I wanted to get most of the lying, once alarm go off at your 12 min of flight you know you have arox 20% left, with coming back home and landing down to 10% batt. at that point I was about 3 volt /cell.
2.6 was ESC shut down, I knew last few min I wasn't not doing hard core 3D it was more like coming back and landing, cool down process. that's why I did that.
Also if you had goof BEC it will do good job volt regulating and keep power nice a steady.

Anyway, good old days

Do you still have any TRex's left? I think I had sold everything 2 years ago but I might still have a 450 sitting around somewhere that has been crashed probably 20 times and repaired as many times. I cut my teeth one practiced heli 3d on a Trex 450 and on a Raptor.

 

[WithTheBirds]

Do not take that as anything more than curiosity, it is highly variable based on how good the current calibration state of the charge meter of a particular battery is, and can go the other way too.

I wouldn't worry too much about the "calibration state" as you put it. The battery GAS Gauging, in particular the time remaining to empty is very accurate, even accounting for cell condition as they age.

Deliberately trying to fly at these low SOC is probably one of the best ways to prematurely age the packs though.

 

[SuperPete]

I wouldn't worry too much about the "calibration state" as you put it. The battery GAS Gauging, in particular the time remaining to empty is very accurate, even accounting for cell condition as they age.

Deliberately trying to fly at these low SOC is probably one of the best ways to prematurely age the packs though.

Like I mentioned above, this is for emergency situation only, just something I had to know for myself and share it with you guys.

Doing so every flight will prematurely age the battery, once here and there will not do any harm.

 

[SuperPete]

Do you still have any TRex's left? I think I had sold everything 2 years ago but I might still have a 450 sitting around somewhere that has been crashed probably 20 times and repaired as many times. I cut my teeth one practiced heli 3d on a Trex 450 and on a Raptor.

I do not, sold them all about 5 years back.
Had to take a brake, you know how it is between crashing and repairing, it got to me at some point I had to check out from it.
My body still got 600E sitting on his shelf, every time i am at his house, we all talk how we did it back then.

 

[Former Member]

I do not, sold them all about 5 years back.
Had to take a brake, you know how it is between crashing and repairing, it got to me at some point I had to check out from it.
My body still got 600E sitting on his shelf, every time i am at his house, we all talk how we did it back then.

I know how you feel. Sometimes if it takes more time to repair it then to fly it it's just not worth the effort. That goes double for flying 3-D. Sometimes for a 5 minute flight it takes 3 or 4 hours to repair

 

[WithTheBirds]

I know how you feel. Sometimes if it takes more time to repair it then to fly it it's just not worth the effort. That goes double for flying 3-D. Sometimes for a 5 minute flight it takes 3 or 4 hours to repair

You can tally the number of mishaps by counting your bent main shafts and tail booms.

 

[mnis]

Unfortunately, such a test is absolute nonsense. Because nobody can derive a flight reliability from it!

My modest tests have shown that the intelligent M1x batteries with 3 single cells switch OFF immediately as soon as the following happens:
- The total voltage of the battery pack drops permanently below 9.9 volts (only a few seconds are sufficient).
- The voltage of one cell of the package drops below 3.30 volts.

Granted, I've done most of the battery testing without an aircraft, but also a few hovering at very low altitudes. It may be that the determination of the remaining energy during the flight, under high current load, somewhat different from my findings.

But even my M1P crashed during a endurance test, from very low altitude, once at 6 percent remaining energy. And here in the forum there are always crash reports at significantly more than 0 percent of remaining energy.

This suggests that the display of the remaining capacity, especially in the lower range (30 to 0 percent) no longer provides sufficient reliability.

For me, the final conclusion is that only between 100 and 30 percent of displayed energy is reliable flying possible. A safe landing should take place at 30 to 25 percent, and be completed at 25 to 20 percent.

So the low-energy warnings of our aircraft are always serious!

 

[Former Member]

Unfortunately, such a test is absolute nonsense. Because nobody can derive a flight reliability from it!

My modest tests have shown that the intelligent M1x batteries with 3 single cells switch OFF immediately as soon as the following happens:
- The total voltage of the battery pack drops permanently below 9.9 volts (only a few seconds are sufficient).
- The voltage of one cell of the package drops below 3.30 volts.

Granted, I've done most of the battery testing without an aircraft, but also a few hovering at very low altitudes. It may be that the determination of the remaining energy during the flight, under high current load, somewhat different from my findings.

But even my M1P crashed during a endurance test, from very low altitude, once at 6 percent remaining energy. And here in the forum there are always crash reports at significantly more than 0 percent of remaining energy.

This suggests that the display of the remaining capacity, especially in the lower range (30 to 0 percent) no longer provides sufficient reliability.

For me, the final conclusion is that only between 100 and 30 percent of displayed energy is reliable flying possible. A safe landing should take place at 30 to 25 percent, and be completed at 25 to 20 percent.

So the low-energy warnings of our aircraft are always serious!

I agree with most of what you said. One thing for a pilot to keep in mind is to try and start each flight at 100% charge. If starting a flight with the battery charged to less than 100%, the battery might not discharge in a linear manner, and the flight time might be alot shorter than expected.

 

[Former Member]

You can tally the number of mishaps by counting your bent main shafts and tail booms.

Not to mention chipped or splintered pairs of $150 per pair CF blades.

 

[WithTheBirds]

Not to mention chipped or splintered pairs of $150 per pair CF blades.

That’s how we know the difference between real carbon fibre blades and the FAUX pretend CF rubbish.

 

[Jackcutrone]

You can tally the number of mishaps by counting your bent main shafts and tail booms.

I have started saving them and also costing out each crash. I have a 600E Pro DFC that I got last spring. Had 84 flights before first crash, a record. At 100 flights I had another. The repairs on that are north of $300 and getting close to what I paid for the bird. Repairs seem to be taking forever because I missed some damaged parts when doing post crash assessment.