Strange Controller Battery Level

[Aliennatn]

I have done two test flights with a new Mavic 2 Zoom and have had some strange battery level readings on the controller.

On the first flight, during the time it took to discharge one Mavic 2 battery to 25% (about 23 minutes), the controller reported its internal battery had dropped from 98% to 23% at the end of the flight. When it was plugged into the supplied charger, I noticed that the controller was now reporting 83% and then quickly charged back to 100%

On the second flight, the controller battery dropped from 100% to 48% during a single Mavic battery discharge (25% left). When I returned to the charger, before plugging it in, I checked the battery level, which was then reported as 87%. After it was.plugged into the supplied charger it quickly charged to 100%

My controller is using the standard side cable to USB-C, and is connected to a Samsung Galaxy S9. The temperature was about 82F and the controller and phone were exposed to direct near noon sunlight at about 49 degrees latitude. I did get a warning from the S9 that charging was paused due to heat on the second flight, but things continued to operate as expected.

Any ideas what is going on here? Did I miss a controller battery calibration or conditioning step somewhere in the manual?

Any tips for helping the controller mobile stay cool?

 

[old man mavic]

two things ,heat and discharge rate the heat is the main factor ,lipos dont like the extremes of heat or cold plus when they are discharging the cell voltage will show lower than it really is,once you let it cool you will find it will recover and this is what you are experiencing try to shade the controller as much as possible from the direct sun not easy i know and make sure you allow the batteries time to cool down before you recharge them you might be able to stop the controller from charging the display in the settings menu this would help

 

[Aliennatn]

two things ,heat and discharge rate the heat is the main factor ,lipos dont like the extremes of heat or cold plus when they are discharging the cell voltage will show lower than it really is,once you let it cool you will find it will recover and this is what you are experiencing try to shade the controller as much as possible from the direct sun not easy i know and make sure you allow the batteries time to cool down before you recharge them you might be able to stop the controller from charging the display in the settings menu this would help

That's what I expected the answer was. I am trying to avoid the hottest part of the day, not just for batteries, but for me too! I guess if its unavoidable maybe I can strap a chilled gel pack on the back of the controller/display and get some level of thermal buffering.

 

[Kilrah]

Discharge the controller completely until it turns off by itself, then charge completely. The "fuel gauge" chip probably lost calibration.
If that doesn't help, battery's faulty.

Above post is opposite of true, lipos perform better when warm, it's the cold they don't like. And one subjected to a low discharge like the controller's one couldn't care less about your warm ambient temps.

 

[old man mavic]

Discharge the controller completely until it turns off by itself, then charge completely. The "fuel gauge" chip probably lost calibration.
If that doesn't help, battery's faulty.

Above post is opposite of true, lipos perform better when warm, it's the cold they don't like. And one subjected to a low discharge like the controller's one couldn't care less about your warm ambient temps.

thats a very strange comment if that was the case why is it that we are told to allow the battery to cool down to room temp before recharging them ,and also the fact that they have protection built in to prevent them charging if they are to hot i have no doubt that very cold temps are not good for batteries because they prevent the chemical reaction that happens during use and just to finish temperature whether hot or cold will have a bearing on performance

 

[Aliennatn]

Discharge the controller completely until it turns off by itself, then charge completely. The "fuel gauge" chip probably lost calibration.
If that doesn't help, battery's faulty.

Above post is opposite of true, lipos perform better when warm, it's the cold they don't like. And one subjected to a low discharge like the controller's one couldn't care less about your warm ambient temps.

Well after several partial discharge/recharge cycles the battery levels are much more consistent. The last flight mission discharged 3 Mavic batteries down to 25% and the controller remained above 50% with a smaller rebound to 65%. The conditions were similar to my first post, however I did a better job of shading the direct sun.

I will try the full discharge and see if the situation improves further, but at this point the performance seems to be acceptable.

 

[Kilrah]

You really need a full cycle to calibrate things properly.

thats a very strange comment if that was the case why is it that we are told to allow the battery to cool down to room temp before recharging them ,and also the fact that they have protection built in to prevent them charging if they are to hot

Charge and discharge are completely different operations with different characterietics.

 

[paulatkin73]

Well after several partial discharge/recharge cycles the battery levels are much more consistent. The last flight mission discharged 3 Mavic batteries down to 25% and the controller remained above 50% with a smaller rebound to 65%. The conditions were similar to my first post, however I did a better job of shading the direct sun.

I will try the full discharge and see if the situation improves further, but at this point the performance seems to be acceptable.

as i just flew another range test - with the 1.8w NLD hack i used up whole battery down to the low battery warning - 3.65v per cell level, i think, smart controller was decently hot in the end, it started with 100% charge - ended up with 87% charge level. so, to use 13% on a single battery sounds OK to me.