How do the batteries discharge themselves?

I think DJI is really smart to use smart batteries. And I mean it is a good thing for users.

Lipo management is complicated when you first get into using them. And most Phantom users are new to model aviation.

I have hundreds of Lipos from tiny 1s 70's to 6s 6000's. And I have 4 testers 2 discharge balancers and about a dozen smart chargers. Well over a thousand dollars worth of chargers, power supplies, and testers. Over the years I have seen 2 lipo fires. and a few other electrical melt downs in my and others models. I have puffed dozens of Lipos and retired lots of them. Some brands are very good and some very bad. You have to break Lipos in gently and be very particular about how they are used, charged, balanced and stored.

There is so much to learn with just the P3, flying safe and all that. DJI just made it simple, as you progress in this hobby your next step may be a more professional MR you build yourself, then you will become part of the wonderful and expensive world of Lipo management yourself. The DJI KISS method is very good move on their part.

I do know there are some very experienced users here, I am not writing for them but for those new to the hobby.
 
I don't have the answer to those questions. However, I can tell you randomly pressing the battery button to check the charge level for no apparent reason is not a normal use case.

I would disagree due to the amount of times I have read people doing such an action on Facebook groups and forums.
 
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I'm also wondering how the balancing is done? They battery itself must do it seems as there are only 2 pins on the charger, but looking in the battery connection on the packs there look like more pins? Confusing system! I suppose it uses a load on each cell to balance, the same load it discharges to storage voltage with?
All the cell points are available out for charge balancer to work. We need two end terminals and two intermediate points to reach each cell.
 
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what balance charger though? the phantom charger only has two pins?
The pins are balance pins, that the P3P uses for telemetry to the RC and to record battery cells into the log that is kept in the P3P.

It is also conceivable that DJI will make a balancing charger at some point but I doubt it this would be redundant. You could make a tester that read each cel voltage but why bother since the telemetry does this in the app.

All and all it is the easiest to use Lipo system I have ever seen. Completely automated made for novices. And it works great.
 
what balance charger though? the phantom charger only has two pins?
Phantom charger is just a power supply, rest all is done internally. I don't have the details of the circuitry inside the battery though I know connecting points are available to balance the charge.
 
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Also, I have read that there is / was a bug where if you checked the pack voltage (pressed the button) the time to discharge counter would actually be reset?
It may not be a bug, but it seems to me to behave like a bug.

If I turned the battery on, resetting the auto-discharge is a brilliant plan. But why would the auto-discharge timer reset itself just because you wanted to check the charge? It doesn't make sense to me.

I agree that this behavior doesn't seem right. So I just did a chat with DJI support and asked if the battery is really supposed to reset the self-discharge timer when you check it's charge level. They knew exactly what I was talking about and said that it WAS a bug, and it has been fixed in the battery firmware that came with 1.6.004. They said that with the latest firmware, checking the battery charge status will NOT reset the timer, but turning the battery on WILL reset the timer. I guess it's time to test this.
 
Let's make few calculations to determine what do we need to discharge batteries:

Total battery capacity: 4480 mAH
Battery is discharged to 60%
So the discharged energy: 4480*0.40= 1792 mAH
Time to discharge: 48 hrs
So discharge rate: 1792/48=37.3 mA
Voltage of battery: 15.2 Volts
Discharge power: 15.2*37.3=0.566 W
Resistance to dissipate=15.2/37.3=407 Ohms

Thus one can use 4 series connected 100 ohms, 1/4 Watts resistors to dissipate the charge in 48 hrs

Your math shows .566W dissipating. Wouldn't that require 1 watt resistors in series? Seems 1/4W would overheat.
 
I agree that this behavior doesn't seem right. So I just did a chat with DJI support and asked if the battery is really supposed to reset the self-discharge timer when you check it's charge level. They knew exactly what I was talking about and said that it WAS a bug, and it has been fixed in the battery firmware that came with 1.6.004. They said that with the latest firmware, checking the battery charge status will NOT reset the timer, but turning the battery on WILL reset the timer. I guess it's time to test this.
Glory be, DJI does think logically. The bug is fixed! Now if they would only start COMMUNICATING ! Geeze. Why are we finding this out on PhantomPilots? They have our email addresses. Can't they send us firmware update summaries? Or is this asking too much?
 
Phantom charger is just a power supply, rest all is done internally. I don't have the details of the circuitry inside the battery though I know connecting points are available to balance the charge.
Those "connecting points" are not accessible without tearing up the internal insulation used for the wiring to each of the cells. It's very tight in there. If you destroyed a battery you can likely trace the wires to the boards to figure out where those points are. But since balancing takes place internally through the integrated smarts onboard, I'm not sure why anyone would want access to those balance points.
 
Does the power light on the battery illuminate while performing the auto-discharge? I have yet to see my P3 batteries auto-discharge even though I have them set to do so in 3 days. I have waited longer than 72 hours before checking the battery status.

It takes about two days to discharge a full battery down to its storage level. The batteries get a little warm during this process, but they never get hot.
 
Does the power light on the battery illuminate while performing the auto-discharge? ...
I don't know but that's a great idea - some sort of indication that it's in an auto-discharge state. Anything. How about a slowly blinking lamp? Give us a clue.
 
I couldn't agree more. I think a good percentage of people would be curious about the state of their batteries and if the discharge process was working. Checking the charge should not reset the discharge cycle. The only thing I can think of is that the circuitry cannot differentiate between checking and actual use. I doubt that, and I'm probably just giving DJI an alibi.
I was under the impression that if a battery was discharging itself the only way to stop it was to place the battery back on charge ,but I could be wrong


Sent from my iPad using PhantomPilots mobile app
 
I have my battery to auto discharge after 3 days but so far no change on the voltage. I fully charged the battery to update my drone but I can't fly because of the weather. So far the battery hasn't discharge at all.
 
We really need to test this. I guess the best way would be to set two batteries' discharge timer to 1 day. Tap the button to check the charge on one of them every day. After 3 days, they should both have discharged to storage voltage. If the tapped one doesn't discharge, we know DJI was blowing smoke. If both have discharged, it's working perfectly. If neither has discharged, we have a problem.

I'll try this and see what happens.
 
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Are FCC compliant Phantom 3 Pro batteries the exact same as CE compliant P3P batteries?
 
Your math shows .566W dissipating. Wouldn't that require 1 watt resistors in series? Seems 1/4W would overheat.
I proposed 4 resistors, each 1/4 watt, thus totaling to 1 Watt against the total dissipation of 0.566 W
 
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I just either fly the Lipos down to 45-70% or charge until 50% on the day I fly. It is easy to do and best for the Lipos. Much better than having them sit fully charged for a few days.

This is the same I do with all my Lipos. Though I have auto discharge on my smart chargers, I rarely use them. On my other models I know how long to fly to land with about 50% power by timing the flight. It is very accurate. And I always use a Lipo tester at the end and beginning of each flight to check the balance and charge state.

On the P3P it is so easy with telemetry available in the GO app. I never fly a Lipo lower than 30% unless it is an emergency, like a dog chasing the model or a bit of really bad wind delaying the landing.

Most of my Lipos last 500 or more cycles, some up to 1000 cycles. Take care of your Lipos and they will take care of you...
 

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