Rapid Drain of Batteries

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I purchased a used Phantom 2 Vision Plus recently and it included 2 batteries. There was a Phantom Knowledge DVD that came with it which I followed to perform all updates. When I attempted first flight I encountered a problem. The drone will take off but the battery drain starts falling about 1% every 10 seconds. By the time it reaches about 80% it drops even more rapid and with less the 5 minutes total flight time it reports critical level and flashes the lights in warning, so I land. Both batteries exhibit the same problem. Prior to flight, the software reports the following
Battery 1
Design Capacity 5200 mAh
Full Capacity 5200 mAh
Current Capacity 5163 mAh
Percent of Charge 99
Percent of Life 98
Discharge Times 8
Temp 23.3
Cell 1 Voltage 4128
Cell 2 Voltage 4154
Cell 3 Voltage 4146

Battery 2
Design Capacity 5200 mAh
Full Capacity 5000 mAh
Current Capacity 4971 mAh
Percent of Charge 98
Percent of Life 99
Discharge Times 3
Temp 23.3
Cell 1 Voltage 4165
Cell 2 Voltage 4033
Cell 3 Voltage 4147

I have drained the batteries to the 8% level then recharged as suggested for every 20 cycles. Still had the issue.
I considered purchasing new batteries, but I wondered can the software report the battery condition as favorable as this and the battery still be bad?
Or is there a problem with the drone? If so is there a way to correct the problem?
 

N017RW

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I purchased a used Phantom 2 Vision Plus recently and it included 2 batteries. There was a Phantom Knowledge DVD that came with it which I followed to perform all updates. When I attempted first flight I encountered a problem. The drone will take off but the battery drain starts falling about 1% every 10 seconds. By the time it reaches about 80% it drops even more rapid and with less the 5 minutes total flight time it reports critical level and flashes the lights in warning, so I land. Both batteries exhibit the same problem. Prior to flight, the software reports the following
Battery 1
Design Capacity 5200 mAh
Full Capacity 5200 mAh
Current Capacity 5163 mAh
Percent of Charge 99
Percent of Life 98
Discharge Times 8
Temp 23.3
Cell 1 Voltage 4128
Cell 2 Voltage 4154
Cell 3 Voltage 4146

Battery 2
Design Capacity 5200 mAh
Full Capacity 5000 mAh
Current Capacity 4971 mAh
Percent of Charge 98
Percent of Life 99
Discharge Times 3
Temp 23.3
Cell 1 Voltage 4165
Cell 2 Voltage 4033
Cell 3 Voltage 4147

I have drained the batteries to the 8% level then recharged as suggested for every 20 cycles. Still had the issue.
I considered purchasing new batteries, but I wondered can the software report the battery condition as favorable as this and the battery still be bad?
Or is there a problem with the drone? If so is there a way to correct the problem?
Without knowing how the batts. were stored, based on your explanation, they are most likely compromised by improper storage.

This means the internal resistance has increased and while they will seemingly test Good (by a crude calculation) they will not deliver the [calculated] capacity. This increased resistance consumes power and creates heat resulting in the effects you described.

So it sounds like your P2 is fine and acting normally.

BTW:The proper long term storage levels are ~40 - 60% charge level. In later products DJI added self-discharging features to help prevent damage from improper long term storage.
 
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Thanks for your input. I have read online accounts of a guy who had a similar issue even with a new battery. So I hope to find someone local who has a P2 so I can either try my batteries in their drone, or their battery in my drone before I shell out for new batteries.
 

N017RW

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Understood.

However notwithstanding what you may have heard from 'a guy'... your batteries are damaged.
 
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Thanks for your input. I have read online accounts of a guy who had a similar issue even with a new battery. So I hope to find someone local who has a P2 so I can either try my batteries in their drone, or their battery in my drone before I shell out for new batteries.

putting your location may help with finding someone

and yes the cells are out of line, the last number should be around + or _ 6 or so of the highest value cell
 
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OK this issue is solved. I ordered a aftermarket battery. No more problems! . A friend explained LiPo batteries to me like this "Even if you have a battery with a 5200 mAh capacity, a portion of that capacity can be unusable. Sort of like having a gallon jug that is partially full of a hardened sludge. Although you can fill the jug up, only the portion that is not sludge is what you get to use." So the answer is YES a battery can show good, but not be.
 
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Both of your batteries had a bad cell. If you look at batt 1Cell 1, Voltage 4128 there is a drop of 18 from the next lower Cell 3 Voltage 4146.
Battery 2 there is a difference of 114 from Cell 2 to Cell 3. Keep un eye on the cells that will tell you alot about the battery. I usually store my batts at 45% and have never had a problem. Some of my batteries have more than 100 discharges and still working fine. Your cells shoud be within 10 of each other or a little higher in some cases.
If you will notice the new batteries will be very close in the mAs. The worst thin you can do is store your battery at 100% for more than 3 days unless it's a self discharge battery and I don't think the P-2 V+ had that feature.
 
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Both of your batteries had a bad cell. If you look at batt 1Cell 1, Voltage 4128 there is a drop of 18 from the next lower Cell 3 Voltage 4146.
Battery 2 there is a difference of 114 from Cell 2 to Cell 3. Keep un eye on the cells that will tell you alot about the battery. I usually store my batts at 45% and have never had a problem. Some of my batteries have more than 100 discharges and still working fine. Your cells shoud be within 10 of each other or a little higher in some cases.
If you will notice the new batteries will be very close in the mAs. The worst thin you can do is store your battery at 100% for more than 3 days unless it's a self discharge battery and I don't think the P-2 V+ had that feature.
This generates a new question. HOW do you get batteries to 45% for storage? How do you identify that it is at that level?
 
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OK this issue is solved. I ordered a aftermarket battery. No more problems! . A friend explained LiPo batteries to me like this "Even if you have a battery with a 5200 mAh capacity, a portion of that capacity can be unusable. Sort of like having a gallon jug that is partially full of a hardened sludge. Although you can fill the jug up, only the portion that is not sludge is what you get to use." So the answer is YES a battery can show good, but not be.

Sorry - but your guy is wrong. That was true of the old NiCd days ... but not of more modern battery tech.

The DJI batterys are LiPo. "N017RW" gave you the reason and I will expand a bit on it :

A battery has to supply WATTS .. volts x amps. It has a designed capacity. That capacity does not change significantly unless physical damage occurs to the internal chemicals or structure of the cells.
What does change is the resistance to providing power as the battery ages. As the resistance increases - the volts drop, to maintain the watts demand to execute the desired motor speed - the amps compensate by increasing. This in turn causes a rise in temperature of the cells - which increases resistance ...

You can now see - the poor battery is fighting a losing battle as it ages. And is why you can basically tell battery state by its ability to perform vs time. As it ages - flight time gets shorter and shorter until you have so short a flight capability - its bin time for the battery. Actually old batterys still have a use ... Bench testing the model ... powering it during updates etc. As long as you are not calling on it to fly - it can still provide the low power needed for such.

Summary :

Internal resistance of cells increases with age / use.
Internal resistance causes voltage drop during power demand - forces amps to increase to maintain required WATTS
Increased amps drains the capacity quicker and gives the impression of reduced capacity.
Battery will usually show signs of increased temperature based on that resistance
Low power demand is still workable with such batterys

Hope that helps.
 
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This generates a new question. HOW do you get batteries to 45% for storage? How do you identify that it is at that level?

Storage level of LiPo batterys ... 3.7 - 3.85V per cell. The P2 has a 3 cell battery > therefore storage level is 11.1V to 11.55V total measured across the main terminals.
 
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This generates a new question. HOW do you get batteries to 45% for storage? How do you identify that it is at that level?
The easiest way is to fly it to 45% useing the app. They have several battery discharge devices that will also do it. Some have a light that will plug in your battery. When only 2 lights remain on your battery that means is 49%. You can't adjust the cells, you can only monitor them with the DJI Phantom 2 Vision Assistant_3.8. The best way to maintain your batteries is not keep them at a high charge for a long time (over 48 hrs.).
 

N017RW

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I simply fly until the batt shows 2-solid, 1-flashing LED.
 
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I simply fly until the batt shows 2-solid, 1-flashing LED.
No, that is not what I said, when the battery has 2 lights it's 49%. If it has 2 lights and a flashing light that means it's over 50%. The top right of the app shows the battery level durning flight.
 
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The problem with the LED lights are the lack of accuracy.

Each light constitutes 25% ... with flashing the intermediate 12.5%. Which sounds fine - but in fact if you think about it - leaves you with quite a margin of error.

As another says - the APP is the one to show battery level. Or as I mentioned earlier ... switch on and put a meter across the contacts and read of the voltage ... 11.1 to 11.6V is OK .. preference at the 11.1V level. (Note 11.1V is the nominal quoted voltage as well ... ).

I thought the P2 had an 'intelligent battery" ?
 

N017RW

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No, that is not what I said, when the battery has 2 lights it's 49%. If it has 2 lights and a flashing light that means it's over 50%. The top right of the app shows the battery level durning flight.
Huh?
What u said?
It’s what I do and have done for about 5 years.
No need to buy devices to waste partial cycling, I just fly!
 
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I'm always amazed at what really is a simple matter seems to get into 'debate' ....

As NO17RW has suggested ........... fly and store !!

Its what I do as well .... yes - I have devices designed to discharge my DJI packs ... but they rarely get used. Normally - I just fly to about 30 - 35% and that's it. Once rested - the battery bounces back anything up to +5% ....

I bench it as is till next needed. If I don't fly one or two batterys ... being P3P batterys - I let my user set 2 day discharge kick in.
 
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