P3P battery problem

[Waylander]

Hi Guys

Anyone come across the following problem with a P3P intelligent flight battery.

(Background).. I always cycle the three batteries I have, I "burnt" them in (yea I know blah blah"), and fly them home around 25 - 30% and store them at around 40% charged, all three batteries have been charged 15 times, and all three battery readings are more or less identical when viewed in the DJI go app. So that is the back ground info, here is the problem:-

Battery No.2 remains "On" all of the time, by "On" I mean current is available at the battery output terminals regardless of the status of the 4 green LED's.

The LED indicators cycle normally if the "On" button is pressed, ie quick press followed by a longer press will give a status readout just as though the battery has been switched "On" normally, the same holds true when using the power button to switch the battery "Off", the illuminated LED's all cycle down until all they are "Off".

If the power "On" button is pressed and held for a period of time until the test routine triggers all 4 LED's show green ie "Normal", so good so far right ..!

Here is the rub... if the battery without any Green LED's showing, is inserted into the P3P the bird immediately powers up without me pressing the "power On" button.

All the LED's are "Off" but the bird will fly, and the battery status in the DJI Go app appears normal and shows a steady drain as the flight time continues.

So anyone got any opinion as to what the problem is, anyone seen this before...? can the problem be fixed..

Regards
Waylander

 

[Mark The Droner]

I've never heard of that before. This problem may be a first!

 

[yorlik]

The smart batts all have a series FET as an on/off switch directly between the cells and the outside connector. The BMS (Battery Management System) chip controls when this turns on and off, with help from the on/off switch on the outside.

Since yours is perpetually on, it means your FET is always on. What can cause this?

Normally when FETs fail, they fail OPEN - or OFF... So to fail ON is pretty unique and thus not so likely.

That means something ELSE failed or shorted oon the pcb inside, TELLING the FET to turn on... Might be a solder joint loose, a fray piece of foreign material (wire etc) that fell on the pcb, oe another smaller failed component. Since the batt takes some jarring in 15 cycles of life, it is likely something mechanically moved to cause the short somewhere that tells the FET to turn on.

In any case, since you are not explicitly telling it to turn on, and since it continues to get jarred in flight, it seems mighty scary to me to USE IT in that condition since what may have fallen across the pcb can just as easily fall away, and then your batt will be OFF in the middle of a flight.

I would not use it again.

 

[Waylander]

Hi yorlik

Yes that makes sense, I assumed the power button did not switch on the current directly, and it did so through a power semi-conductor of some sort ( a FET as you say ), I am reluctant to open the battery or in fact to continue to use it. even though current is available at the output terminals I did still go through the normal switch on/off procedure,
I'm going to see if DJI will exchange it.

Thanks for your response

Regards
Waylander

 

[Dronason]

Don't open or use it. Either trash it (recycled I mean) or try to get it replaced by DJI as it seems to be a failure of the electronic, not the cells.

 

[Waylander]

Don't open or use it. Either trash it (recycled I mean) or try to get it replaced by DJI as it seems to be a failure of the electronic, not the cells.

Roger on that, I've contacted DJI who are looking into the problem, the battery is only 8 months old with 15 charges..

 

[Dronason]

Wish you get positive answer from them.