80 to 90% battery level takeoff is triggering outrage

[msinger]

what voltage readings should you use when deciding to return or RTH?

Check out this post.

 

[GadgetGuy]

Right. This issue has not resurfaced since then.

DJI's solution, rather than disabling the shutoff at below 3.0V while in flight, was to cripple power output at launch to prevent reaching 3.0V. The battery still shuts off when any one cell reaches 3.0V even in flight. This battery protection "feature" totalled another P3P of mine when merely 20 feet away and 30 feet in the air, during landing when fighting a windy conditions with 7% remaining. I would much rather damage a $100 P3 battery than total the $800 aircraft. I only needed 10 more seconds of battery to safely complete my landing. The "Smart" battery could easily have safely landed my P3P, had DJI simply disabled voltage triggered battery shutoff when airborne, instead of throttling takeoff power, to solve the crashes caused by launching at full power at 70°F or below with a stored battery that has entered the discharge state.

 

[John Locke]

DJI replaced my P3P under warranty with a cannibalized P3A ..... Flight records clearly show a voltage drop on one cell to 3.0V just before shutoff in midair from 215 feet. It was in a discharge state, even though the battery remaining percentage reported 87% at takeoff.

Glad you got a replacement bird, although not new.
Your story is interesting. I've never heard anyone on 1.4 firmware have the issue of sudden midnight power loss, only 1.5 I've heard this issue. Your story matches other 1.5 firmware stories about shutting down when a cell reaches 3.0V. Even DJI told me at CES this only occurs on 1.5, and that claim was echoed at both of their booths, coming from two different technical guys familiar with firmware issues. Very interesting, seems clear that 1.4 is flawed. I think the leds are also flawed in the battery level reporting, showing four LEDs as fully charged during the time when battery discharge is occurring, that's just wrong. I have a friend still running 1.4. I'll let him know your story.
Yes, it's critical to top off batteries before flight with P3.

As for P4 I think they got way more conservative on the battery calculations. If you compare the percentages versus voltages between similar flights of P3 and P4 you'll see a big difference, a larger margin of safety in the P4. I think that's why we DON'T get the claimed 28 min flight time. I think they got conservative with the P4 battery monitor algorithm, after they measured 28min flight times using the old algorithm. Marketing never updated the resulting flight times....just a guess.

 

[GadgetGuy]

Glad you got a replacement bird, although not new.
Your story is interesting. I've never heard anyone on 1.4 firmware have the issue of sudden midnight power loss, only 1.5 I've heard this issue. Your story matches other 1.5 firmware stories about shutting down when a cell reaches 3.0V. Even DJI told me at CES this only occurs on 1.5, and that claim was echoed at both of their booths, coming from two different technical guys familiar with firmware issues. Very interesting, seems clear that 1.4 is flawed. I think the leds are also flawed in the battery level reporting, showing four LEDs as fully charged during the time when battery discharge is occurring, that's just wrong. I have a friend still running 1.4. I'll let him know your story.
Yes, it's critical to top off batteries before flight with P3.

As for P4 I think they got way more conservative on the battery calculations. If you compare the percentages versus voltages between similar flights of P3 and P4 you'll see a big difference, a larger margin of safety in the P4. I think that's why we DON'T get the claimed 28 min flight time. I think they got conservative with the P4 battery monitor algorithm, after they measured 28min flight times using the old algorithm. Marketing never updated the resulting flight times....just a guess.

But for the throttling of power output at launch after 1.6, the battery shut off in flight would still be happening. It's just wrong to shut off any battery in flight, to protect the battery, even if a battery cell drops below 3.0V. Let the $100 battery be damaged, and allow whatever remaining power exists to safely land the $800 aircraft! If the aircraft crashes, it destroys the battery anyway. Dumb programmers! This problem has existed since 1.1.9. Something in 1.5 may have exacerbated it, but it wasn't caused by 1.5. It is caused by shutting a working battery off in midflight, which it still does, whenever any cell drops below 3.0V. That's as true of the P4 as the P3!

I agree with you about the P4 more conservative battery calculations. Refusing to top off a stored P4 battery until it drops to 95% is also wrong! The smart batteries are causing problems because they are stupidly programmed for an aircraft that needs battery power to stay in the air.

 

[John Locke]

It's just wrong to shut off any battery in flight, to protect the battery, even if a battery cell drops below 3.0V. Let the $100 battery be damaged, and allow whatever remaining power exists to safely land the $800 aircraft!

Yeah, I've said the same from the beginning of these events. Fortunately I have avoided such events by topping off before I fly.

I believe the shut down at 3.0V is intended to prevent damaging batteries when someone accidentally puts the drone away in the bag and forgets to turn off the drone. I bet that happens all the time, given the thrill of flying and the excitement of the craft returning with no damage, they simply absentmindedly forget it. This is a good safety feature to keep from ruining a good $130 battery. HOWEVER..... it is absolutely dumb to not include of a requirement in the battery firmware that requires the drone to "NOT BE FLYING!" before turning it off. I'm perplex, after all the really cool software features that are in this drone, years ahead of the competition, that they missed this in their logical thinking for battery protection. It makes no sense at all.

Are you sure 1.6 will still do this while flying? Have you experienced this firsthand? If yes, can you provide details?

 

[Imabiggles]

What's your objection? Please start taking off at 50% charge. Nothing bad will happen if you can ensure that your battery had 50% charge remaining and also start planning to take it down when remaining charge is about 25-30%. Don't base your planning on the charge shown on the controller. That's the secret.

On the serious note: to make everything work perfectly, the built in instrumentation should be accurate which is NOT. So what's the alternative with you: Safety first.

in fairness re: battery monitoring. When LIPOs are measured solely by voltage, its inherently inaccurate. If you had precise measurement of internal resistance, voltage and amperage draw, as well a functional capacity - then you're in business. The way DJI does it is just like the billions of cell phone battery gauges. Nothing wrong with the technique IF you know the limitations.

 

[N017RW]

Disagree somewhat.
Voltage under load is the only way to prevent damage during discharge. It's the basis of LiPo LV alarms that have been in use for a decade +. The other stuff is wizz-bangy distracting info which will not help you in any way while flying.

 

[flyNfrank]

Are you sure 1.6 will still do this while flying? Have you experienced this firsthand? If yes, can you provide details?

Yeah what he said?

I was under the impression that v1.5.3 was the main version that caused the issues to start with. It was the suppose to have been what was referred to at the time as "patched" at v1.5.7. This patched version included battery firmware update as well.

And basically what the patched version consisted of was removing the automatic shut down at 3.0v's per each battery cell.
Reduced overall performance once the outside air temp drops below roughly 70 degrees(power reduced, flight pitch & speed reduced, r/c stick control manipulated).

 

[GadgetGuy]

Yeah, I've said the same from the beginning of these events. Fortunately I have avoided such events by topping off before I fly.

I believe the shut down at 3.0V is intended to prevent damaging batteries when someone accidentally puts the drone away in the bag and forgets to turn off the drone. I bet that happens all the time, given the thrill of flying and the excitement of the craft returning with no damage, they simply absentmindedly forget it. This is a good safety feature to keep from ruining a good $130 battery. HOWEVER..... it is absolutely dumb to not include of a requirement in the battery firmware that requires the drone to "NOT BE FLYING!" before turning it off. I'm perplex, after all the really cool software features that are in this drone, years ahead of the competition, that they missed this in their logical thinking for battery protection. It makes no sense at all.

Are you sure 1.6 will still do this while flying? Have you experienced this firsthand? If yes, can you provide details?

When you say "do this" I am assuming you mean shut off the battery in midflight when any cell voltage drops below 3.0V. It still does. They haven't changed that. What they have changed is allowing full throttle takeoff when the battery is below 70°F, which led to the voltage triggered shutoff, on an improperly balanced discharging battery. The inherent problem of EVER shutting off a battery in flight, by first checking the "NOT BE FLYING" status has NOT been fixed! DJI??? What are you thinking?

 

[skyeboysteve]

Regarding topping off batteries before flight; I thought I read somewhere, that a battery that's sat around for a 24 hours after last charge, needs to be discharged below 85% before being charged... does anyone know if there's validity to that?

 

[WetDog]

Regarding topping off batteries before flight; I thought I read somewhere, that a battery that's sat around for a 24 hours after last charge, needs to be discharged below 85% before being charged... does anyone know if there's validity to that?

Never heard of that one. But this is the Internet where men are men, woman are men and children are FBI agents.

I top mine off all of the time and leave one on the charger for 'emergencies'. Have no idea if this causes some increased wear on the battery but I bought the thing to take pictures with, not as a collector's item. Batteries are 'consumables'.

 

[GadgetGuy]

Never heard of that one. But this is the Internet where men are men, woman are men and children are FBI agents.

I top mine off all of the time and leave one on the charger for 'emergencies'. Have no idea if this causes some increased wear on the battery but I bought the thing to take pictures with, not as a collector's item. Batteries are 'consumables'.

Amen! All this concern about prolonging the battery life for years on multiple batteries I won't be using a year from now, as the P5 won't be using them! Use 'em up as fast as you can, and buy more if you need them! By then they will be less than half the price!

 

[skyeboysteve]

Well, I wasn't so much concerned about over-all battery life, but wondering if I could skip that step of discharging before recharging--it's rather annoying. I thought I read it on DJI's official forum in late December; but can't find it now.

 

[GadgetGuy]

Regarding topping off batteries before flight; I thought I read somewhere, that a battery that's sat around for a 24 hours after last charge, needs to be discharged below 85% before being charged... does anyone know if there's validity to that?

Total B.S.! I top all of mine off every time before flight to 100% whether I charged them yesterday or last week. Never had a battery failure, although I have had two shut off in mid air due to a stupid smart battery that doesn't check for "in the air" status before shutting off when any cell drops below 3.0V!

What is true is that a P4 battery CANNOT be topped off, ever, unless it first drops to 96%! It has to be manually run down to 96% to top it off to 100%! Can you say DUMB? How can you follow DJI's own edict to always start with a fully charged battery, if DJI's so called "smart" P4 battery won't let you top off a P4 battery, like you can a P3 battery?

 

[GadgetGuy]

Well, I wasn't so much concerned about over-all battery life, but wondering if I could skip that step of discharging before recharging--it's rather annoying. I thought I read it on DJI's official forum in late December; but can't find it now.

All you have to do is turn the P3 battery on while it's hooked up to the charger! It will start topping off immediately.

On the P4, you have to go through the annoying process you refer to, to drop the charge level to 96%, and then you still have to turn the battery on to get it to start charging, to top it off to 100%. DUMB!

 

[AWESOME AUSSIE FLYOVERS]

what is the right voltage to fly at had 3 batteries critical it was cold weather about 80% battery power

 

[GadgetGuy]

what is the right voltage to fly at had 3 batteries critical it was cold weather about 80% battery power

The key is to never let any cell under load (cold exacerbates the problem) drop below 3.0V. As soon as that happens, the battery will shut off, even if in flight! Unbalanced cells will do this, regardless of the displayed remaining battery percentage, because it assumes equally balanced cells.