Battery Discharge/Charge question?

[jakeaheli]

Hey all,

I did my first total discharge cycle after about 44 flights. Just found out that you have to do it every 20 cycles or so.

Flew till about 8% then left the AC idle till it died out completely. Waited for battery to cool then charged her up full. Took about 1.5 hours.

I have 2 questions, looking at the picture:

1) Is it normal for the first 2 cells to have a lower voltage than the other 2?

2) I have set to one day discharge if I don't fly. Does the battery have to be out of the drone for this to happen?

Thanks for any help
Jake

 

[Meta4]

Just found out that you have to do it every 20 cycles or so.

You don't have to do that at all.
If it was important, DJI would tell you in the manual (but they don't)

Flew till about 8% then left the AC idle till it died out completely.

Flying to 8% or leaving a Phantom idling (with props on) are both unsafe practices.

Forget about discharging every 20 cycles.
It's a myth.

 

[tcope]

This used to be recommended by DJI but I think they have since removed it from the manual. Also, the procedure was to fly to 20 or 30% and then over until down to 8%. Not 0%. If a lipo is actually taken down to 0% there is a _very_ good chance it will no longer hold a charge. 0% on the app is not 0% on the battery. It's DJI's critical shut down percentage (probably closer to 3% on the actual battery).

 

[DanMan32]

0% on a P3 is about 3.4v per cell which is reasonably safe for short periods. I tried seeing when the AC would shut off, it went below 3.00v and still did not shut down. I was suprised and don't recommend doing this.
What was the average cell voltage when it shut off for you.
I wouldn't worry about a 0.01v variance.

 

[WilliamM]

Hey all,

I did my first total discharge cycle after about 44 flights. Just found out that you have to do it every 20 cycles or so.

Flew till about 8% then left the AC idle till it died out completely. Waited for battery to cool then charged her up full. Took about 1.5 hours.

I have 2 questions, looking at the picture:

1) Is it normal for the first 2 cells to have a lower voltage than the other 2?

2) I have set to one day discharge if I don't fly. Does the battery have to be out of the drone for this to happen?

Thanks for any help
Jake

Like the others have said, this is no longer recommend by DJI. And even back when it was, it was only to 8%, not zero. Also don't charged your batteries to full just the hell of it, and have the auto discharged come on in 24 hours to discharge them. If you don't plan on flying anytime soon, just charge to around 50%, then charge to full on the day of flight.

 

[jakeaheli]

Thank-you for all the replies.

I had no clue that this practise was not required anymore. From all the videos and posts that i've been researching folks have recommended discharging to about 8% or less or until the AC doesn't turn on. If its not needed then I won't worry about it anymore. One more less thing to do.

DanMan32 - My first cell voltage before shut off was 2.99V, the second was about 3.01V while the other two were a bit higher than 3.1V something. At this point i was panicking. I read somewhere that it would shut off as soon as the AC reaches 3.00V... To my relief it did a couple of secs later. I definitely won't be doing this again if this is NOT required.

How many flights have you guys done without any issues on the P3 without having to discharge cycle the battery?

One more question - Does the auto-discharge feature ONLY work when the battery is inserted into the drone?

Regards,
Jake

 

[solentlife]

a) Do not deep discharge any lipo ... its bad news.
b) Do not idle a P3 on the ground ... its an accident waiting to happen and second you can overheat the camera / gimbal as there is no real cooling effect there from flight.
c) If you fly and battery comes down around the 30% mark ... then you are at good level to store the battery - you do not need 50% ... that's the upper storage voltage level.
d) One day auto discharge is good. And it is best to not leave battery in the model. It will auto discharge but note that if you touch the on / off button to check level ... the auto timer will reset and wait till next day to restart discharge. Leave battery alone ...

Nigel

 

[jakeaheli]

a) Do not deep discharge any lipo ... its bad news.
b) Do not idle a P3 on the ground ... its an accident waiting to happen and second you can overheat the camera / gimbal as there is no real cooling effect there from flight.
c) If you fly and battery comes down around the 30% mark ... then you are at good level to store the battery - you do not need 50% ... that's the upper storage voltage level.
d) One day auto discharge is good. And it is best to not leave battery in the model. It will auto discharge but note that if you touch the on / off button to check level ... the auto timer will reset and wait till next day to restart discharge. Leave battery alone ...

Nigel

Hi Nigel,

Thanks for the info and for clearing the auto-discharge part up for me. I won't discharge my battery to those levels every again. I also usually also fly to up about the 18-20% mark before i land.

Would this be a good level to store the battery as well? I usually fly about 1-2 times a week weather permitting.

Jake

 

[solentlife]

This is table of voltage vs capacity and storage etc.

The standard LiPo charges to 4.2V per cell but DJI uses a High Voltage version which charges to max 4.35V per cell. For the first approx. 10% of power use - this makes a difference but once discharge gets down below that 90% level - the LiPo behaves same as a standard.

Recc'd storage level of LiPo's is at 3.7V to 3.85V per cell .... which basically the DJI stated 15.4V nominal is about right. The DJI is a 4 cell battery.

Your 18 - 20% is smack on the 3.7x V and is fine ... but I would not advise storing lower than 15% .... as you see from the table above.

Note : my posts are based on my use of lipo's for many years and over 50 models all ready to fly. Others may have their 'systems' and not necessarily agree with mine.

The main thing to be aware of : LiPo's are nothing like NiMh / NiCd's etc. that we treated to hellish life ! Deep discharge and topping up was common on those - but not to be done with LiPo's ....

Nigel

 

[DanMan32]

I don't believe that table is accurate with regards to DJI display %. When battery level reaches 0% on display, cell voltage is around 3.4v. It does seem accurate in general LiPo industry practice though.

My P3 did not shut off where cells went below 2.9xV. This occurred with two batteries I tested with though the 2nd I didn't let it go as low as the first.

DJI percentages are conservative on the 0% and 'storage %" so I wouldn't worry so much.

 

[Quamera]

Thank-you for all the replies.

I had no clue that this practise was not required anymore. From all the videos and posts that i've been researching folks have recommended discharging to about 8% or less or until the AC doesn't turn on. If its not needed then I won't worry about it anymore. One more less thing to do.

DanMan32 - My first cell voltage before shut off was 2.99V, the second was about 3.01V while the other two were a bit higher than 3.1V something. At this point i was panicking. I read somewhere that it would shut off as soon as the AC reaches 3.00V... To my relief it did a couple of secs later. I definitely won't be doing this again if this is NOT required.

How many flights have you guys done without any issues on the P3 without having to discharge cycle the battery?

One more question - Does the auto-discharge feature ONLY work when the battery is inserted into the drone?

Regards,
Jake

Since you have asked twice and no one has answered the question directly I will say that the auto discharge is a function of the battery, it doesn't matter whether it is in the AC or not. Of course the best course of action is not to use the auto discharge at all, just charge to 50% in the first place or if the battery is already fully charged do a short flight or use the flight simulator to partly discharge it.

 

[jakeaheli]

Since you have asked twice and no one has answered the question directly I will say that the auto discharge is a function of the battery, it doesn't matter whether it is in the AC or not. Of course the best course of action is not to use the auto discharge at all, just charge to 50% in the first place or if the battery is already fully charged do a short flight or use the flight simulator to partly discharge it.

Thankyou Quamera for clearing this one up. Good to know that the battery can do this on its own without having to be inside the AC. I know what to do from next time onwards - will let it auto-discharge for now.
I just purchased one of these devices - TELESIN Adaptom3 SE Discharger for DJI Phantom 3 Battery-5.69 Online Shopping| GearBest.com

Think they will come handy next time i charge up and can't fly the next day or two.

Once again thankyou all for the input

 

[solentlife]

The dischargeer is a good tool but slow.

The real advantage of it ... instead of just wasting the discharged energy as heat - you can actually plug your Controller or tablet / phone into the USB socket of it to charge that up.

As to answering the 'in or out' ... that was answered actually by myself and others .... but most likely missed because we were answering most of your questions.

To "DanMan32" - in fact the LiPo whether HV or standard format behaves near identical once the initial top 10% is used ... storage voltage, empty values etc. are all same. The difference is only in being able to push to a slightly higher voltage.

Nigel

 

[jakeaheli]

The dischargeer is a good tool but slow.

The real advantage of it ... instead of just wasting the discharged energy as heat - you can actually plug your Controller or tablet / phone into the USB socket of it to charge that up.

As to answering the 'in or out' ... that was answered actually by myself and others .... but most likely missed because we were answering most of your questions.

To "DanMan32" - in fact the LiPo whether HV or standard format behaves near identical once the initial top 10% is used ... storage voltage, empty values etc. are all same. The difference is only in being able to push to a slightly higher voltage.

Nigel

I do plan on using the excess power to charge up my mobile phone or my mp3 player. There's always some device that needs to be boosted That would be a good investment for me since we are entering the winter season here.

I've decided to leave the battery out - i think its a good idea due to the battery potentially heating up on discharging.

Thanks again

Cheers

 

[DanMan32]

To "DanMan32" - in fact the LiPo whether HV or standard format behaves near identical once the initial top 10% is used ... storage voltage, empty values etc. are all same. The difference is only in being able to push to a slightly higher voltage.

Nigel

You missed my point. This is a site catering to DJI products. DJI's scale of charge % to voltage is different than generally accepted voltage to cell remaining capacity. DJI leaves a conservative margin on what they register as 0%. That's why using the charge to near zero doesn't cause any harm. The battery still has quite a bit of remaining charge left. It even begins landing at 10% and won't start motors if on the ground with 10% or less. Problem is, you can go "sub-zero", even to potentially damaging low levels if you continue leaving it on.
Toyota did the same thing with their Prius that had a NiMH pack. 0 and 100 charge level on the screen was actually 10 and 80% or don't close to that and system would resist going near those levels.

 

[solentlife]

Dan ... no you missed the point.

The table is posted so people have a better idea of what condition they leave their battery's in and what DJI decides is another matter and seems to only worry you. The fact of the matter is .... 30 - 40% is the prime storage level and the 50% that often gets quoted is right on the max point.

Anyone who repeatedly pushes their battery to 10% will soon realize their error when they have to buy a new battery.

Nigel

 

[Alan Russel]

Well I got my battery down to 10% then recharged fully and capacity went from 4010 mah to 4218 mah...it all helps for more flight time.

 

[solentlife]

Well I got my battery down to 10% then recharged fully and capacity went from 4010 mah to 4218 mah...it all helps for more flight time.

The DJI system cannot report exactly what is a battery capacity ... that's a fallacy. In fact only full on testing can do that by analysing run time vs voltage vs amps etc.

The DJI system only calculates a 'probable' figure by using voltage detected. If you had noted previous charged voltage per cell against what you now say is 'rejuvenated' capacity - you would have seen a small voltage jump. It does not in any way mean suddenly your battery is better.

There is also the false belief that deep discharge resets the battery 'counter' ... sorry not true.

DJI do not allow you enough access to the cells themselves to determine true states. They only report via the charge control board.

Nigel

 

[Alan Russel]

OK...thanks for that info.

 

[DanMan32]

Battery intelligence could also be calculating voltage/current/time and gathering capacity from that.