80 to 90% battery level takeoff is triggering outrage

And we go round and round in circles yet again.

As I said I have seen this happen with my own eyes, with a battery not fully charged in auto discharge, critical voltage warning after 1 minute of flying.
 
As I said I have seen this happen with my own eyes, with a battery not fully charged in auto discharge
Circles are no fun.

Please tell us some more about this. How did you prove it was in auto discharge at the time?
 
Auto discharge set to 10 day, it was about 14, took off at 65%.

1 minute later critical power warning.

I landed very quickly from 100m or so.

Charged battery and flew fine next day.
 
Hi,
I am often in the field with batteries charging on two car chargers, and lots of great photographic opportunities happening. I will, on occasion, fly before my battery has fully charged and I have not had issues.

This could be (in theory) risky. How much you give a hoot about theory is up to you, personally I wouldn't risk it but I swing massively to the side of caution!

My understanding is the last bit of the charging is about levelling the cells. stopping the charging early means this is the bit that isn't happening. So (in a theoretical extreme example to emphasis the point) a battery that shows 80% charge could have 3 cells at 90% and one cell at 50%. The more often you stop the charging process before its completely finished the more of a risk this could become.

Due to that, it's my belief that taking off with a batt that has been charged from 30% to 80% is more risky than re-taking off with a batt that has just been discharged from 100% to 80%
 
Auto discharge set to 10 day, it was about 14, took off at 65%.
So, you think it took more than 4 days to auto discharge? That's odd. How could you tell it was still auto discharging at that point?
 
My understanding is the last bit of the charging is about levelling the cells. stopping the charging early means this is the bit that isn't happening. So (in a theoretical extreme example to emphasis the point) a battery that shows 80% charge could have 3 cells at 90% and one cell at 50%. The more often you stop the charging process before its completely finished the more of a risk this could become.
Couldn't you prove or disprove this theory by looking at the battery cells in the DJI GO app?
 
My understanding is that if you fly a battery from 100% to 60% or whatever, you're safe to use it again[provided you monitor voltage - ALWAYS ALWAYS ALWAYS monitor voltage] provided you use it again WITHIN 24 hours.

Another reason they drop when not fully charged [in my opinion] is due to cold weather and/or someone jamming the throttle to full up which sucks power down below 3.3volts, which causes the battery to auto-shutdown. Full throttle isn't a problem with 4volts, but when you're at 3.7v already, that full throttle could be the kiss of death.

DISCLAIMER: these are my opinions and theories, not necessarily facts.
Auto discharge set to 10 day, it was about 14, took off at 65%.

1 minute later critical power warning.

I landed very quickly from 100m or so.

Charged battery and flew fine next day.

Glad you didn't travel far away Btw I never once trust that auto discharge function on my batteries I always discharge my batteries the night before flight next day.
 
My understanding is that if you fly a battery from 100% to 60% or whatever, you're safe to use it again[provided you monitor voltage - ALWAYS ALWAYS ALWAYS monitor voltage] provided you use it again WITHIN 24 hours.

Another reason they drop when not fully charged [in my opinion] is due to cold weather and/or someone jamming the throttle to full up which sucks power down below 3.3volts, which causes the battery to auto-shutdown. Full throttle isn't a problem with 4volts, but when you're at 3.7v already, that full throttle could be the kiss of death.

DISCLAIMER: these are my opinions and theories, not necessarily facts.

Noob here. Can you tell me what the voltage should be and at what point should I be concerned and bring it back?
 
I treat these batteries like they dumb, the operating characteristics of LIPO chemistry are well understood. Charge as close to when you fly as prctical. Dont run down below 20% state of charge. Allow to cool before charging and store in a cool place between 40 and 60% charged (leave them sitting on the shelf fully charged causes them to loose capacity and reduces the service life of the pack). Keep an eye on the balance of the cells in the pack, voltage variances between cells are a warning sign suggesting that one cell may collapse under load. The problem with taking off on a partly charged pack is that the cells may be out of balance leading to unexpected failure under load. Charging rebalances the cells. Personally i am comfortable to fly a partly charged pack within an hour of last use if the cell balance looks good (i continue to monitor in flight). I will take it easy though, avoid going far away or over water or anywhere a hasty landing would mean a total loss.
 
In dumb batts the charger balances the cells constantly all the way to full. From my exp pushing a 50% chgd batt hard by flying hard will create enough of a voltage drop to under power a receiver. In fixed wing immediatly flying easy will allow the batt volts to return so the rx will initialize and come bak online. Hence u dont fall from the sky due to gliding w fixed wing. Quads on the other hand dont glide. Batt voltage is dependant on the load its being ask of. If the load is too great the volts will drop below the needed requirement. Hence a shut down. Which for quads is a bad thing. Thots??
 
If the load is too great the volts will drop below the needed requirement. Hence a shut down.
It seems this is what DJI believes is happening since they made changes in the latest firmware to throttle the power when needed.
 
There are two very simple ways to avoid this problem:

  1. Update to the latest firmware. It's not 100% certain it is fixed but DJI indicated they made changes to address it.
  2. Do not fly on partially charged batteries that have been sitting for a long period (e.g. > one day).

Note: It is OK to fly on partially charged batteries if you use them right away. On set, we take off, shoot and land multiple times on one battery. Not a problem.
 
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In dumb batts the charger balances the cells constantly all the way to full. From my exp pushing a 50% chgd batt hard by flying hard will create enough of a voltage drop to under power a receiver. In fixed wing immediatly flying easy will allow the batt volts to return so the rx will initialize and come bak online. Hence u dont fall from the sky due to gliding w fixed wing. Quads on the other hand dont glide. Batt voltage is dependant on the load its being ask of. If the load is too great the volts will drop below the needed requirement. Hence a shut down. Which for quads is a bad thing. Thots??
Your assumption is not correct. If this is true, no one would be able to fly at 50% charge ever. Secondly a good battery is capable of delivering rated current at up to low charges safely without creating voltage drops. Additional Voltage drops will occur if there are poor connections or ESC is unable to limit the currents. Good battery will have its internal resistance within the specified limits.
 
I think I've read every battery thread and every drop from the sky thread of the past four months. What's interesting is that it seems to be the P3s that are dropping, as opposed to the P2s. Why would that be? Because the batteries are the same technology in both crafts.

It seems to me to be related to the auto-discharge. Many P3 owners change their auto-discharge to something low (like 3 days) in the belief that it's best for the health of the battery not to let it sit around for a week at full charge. But P2 owners can't do that. They're stuck waiting 10 days for the auto discharge to kick in.

Meanwhile the P3 owners are grabbing their batteries after 4-6 days and checking the charge. The charge seems adequate, so they fly and their craft falls from the sky.

And another P3 guy, who had cleverly charged his battery all the way up before he flew, even though it was already charged pretty high, flies fine. In fact, he flies, he lands, he flies another battery. Lands, and then flies again using the first battery when it has only 50% charge. And what happens? Nothing. And he does this all the time and he tells everybody in the thread that he does it all the time and nothing ever happens and so he concludes there's nothing wrong with flying with a partial charge and all of us complaining that we shouldn't fly with a partial charge are crazy and stupid and wrong.

The common denominator is the auto-discharge. If your battery begins auto-discharge, and you don't recharge it, it has a good chance of shutting down in mid flight.

Why? I don't know. Nobody seems to know. But if you read through these threads you see it happening.

Hey, I don't even have a P3, so what do I care? But if I did have one, I'd keep the auto-discharge at 10 days, and I would be sure to top off the charge before I flew. I also would not be concerned about re-using a battery with a seemingly adequate charge on the same day without having charged it.
 
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And we go round and round in circles yet again.

As I said I have seen this happen with my own eyes, with a battery not fully charged in auto discharge, critical voltage warning after 1 minute of flying.

That's more of a software issue than this battery issue at hand ;) I've done quite opposite and never had an issue!!

The other hand I flew recently in 18 degree weather. I landed around 32% battery. 10 minutes later I fired it back up and took off to get one last quick shot. Critical battery error and auto landed beyond my control. We COULD blame the battery but.. really?
 
There are two very simple ways to avoid this problem:

  1. Update to the latest firmware. It's not 100% certain it is fixed but DJI indicated they made changes to address it.
  2. Do not fly on partially charged batteries that have been sitting for a long period (e.g. > one day).

Note: It is OK to fly on partially charged batteries if you use them right away. On set, we take off, shoot and land multiple times on one battery. Not a problem.

Your number 2 'advice' is NOT 100% correct!!
Nor is your "note" correct, either.
 
In dumb batts the charger balances the cells constantly all the way to full. From my exp pushing a 50% chgd batt hard by flying hard will create enough of a voltage drop to under power a receiver. In fixed wing immediatly flying easy will allow the batt volts to return so the rx will initialize and come bak online. Hence u dont fall from the sky due to gliding w fixed wing. Quads on the other hand dont glide. Batt voltage is dependant on the load its being ask of. If the load is too great the volts will drop below the needed requirement. Hence a shut down. Which for quads is a bad thing. Thots??
The flight controller and receiver typically run on 5 v. As long as the total voltage of the pack is above 5v the voltage regulator will supply enough voltage to the FC and receiver.
 
The common denominator is the auto-discharge. If your battery begins auto-discharge, and you don't recharge it, it has a good chance of shutting down in mid flight.
If all of this is true, then I'm assuming we'll see the same rate of failure even for those running firmware 1.6. Only time will tell now I suppose.
 

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