I was running very high battery temps today. 5 in total all running at these temperatures. It was 24 degree Celsius outside. Is this normal? Is this safe? As you can see this battery has only been charged 6 times.

yes mine have reached the same, or slightly more at times

Thanks rayrokni!

How long does the P3 take to warm up? If it takes a long time - do an IMU calibration in a room of about 20-24 degrees C.

Phuglie Posted at 2015-9-13 08:19
How long does the P3 take to warm up? If it takes a long time - do an IMU calibration in a room of a ...

Please explain to me what calibrating the IMU has to do with the batteries heating up during operation? I'm all ears.

From my experience with lithium based batteries, both lithium ion and lithium polymer, high battery temperatures are associated with high current charging and use.  Running your Phantom at full speed for more than a minute or two will heat the battery up fast. Heat in a battery is not your friend.

The last firmware update supposedly did something to the motors or so the release notes indicated. Nothing else was posted to indicate whether they scaled back the current draw to get longer battery life, or if because of new motors being used on the Phantom, that the intelligent battery needed to know which motor was being used.

I've purchased LiFePO4 packs for my hexacopter that are rated @ 60C for current draw. The higher the current rating, the cooler the battery will run under load. A similar battery with the same milliamp hour rating but a lower C rating heats up FAST.

gregg1r Posted at 2015-9-13 14:09
Please explain to me what calibrating the IMU has to do with the batteries heating up during opera ...

The IMU is heated to a particular temperature before the craft will allow normal operation and take off. Depending on how the IMU is calibrated, this particular temperature can vary - see http://forum.dji.com/forum.php?m ... 2&fromuid=34826 .

The point I'm making is that the higher the IMU temperature - the higher the battery temperature and the greater drain on the battery to maintain it.

You don't agree???

Phuglie Posted at 2015-9-13 09:22
The IMU is heated to a particular temperature before the craft will allow normal operation and tak ...

No, I don't agree.

The battery is being heated up because it's being taxed to the maximum by the motor current draw. The more demand you place on the motors, the more current they draw, the higher the battery temperature will get.

DJI could have added a higher capacity battery to the Phantom 3, but that would have added weight and cost. The Inspire 1 has two battery options, the TB47 and TB48. If operated under the same conditions, the TB48 battery runs cooler than does the TB47. The difference is capacity, weight and cost.

If you put the Phantom in the freezer for a few hours, then pull it out, install the battery and perform an IMU calibration, the IMU might marginally calibrate faster than calibrating at 100F. The battery is still going to be the same temperature, whether you use a hot or cold IMU calibration.

The battery in the Phantom is being taxed to the maximum by spirited operation. The more throttle you give it, the more current you require. The voltage closely stays the same until close to depletion.

I have some high powered flashlights. One light has the ability to use an extension tube so that instead of using 4 batteries in parallel, that it uses 8 batteries in parallel. If I run the light @ 4000 lumens for 15 minutes only using the 4 battery configuration, the batteries get warm, fast. If performing the same test but using the 8 battery configuration, the battery stay close to room temperature. I'm still using the same voltage, but I've increased the current available.

Yes when i flight I va he the same temperatures on my Phantom 3 pro

gregg1r Posted at 2015-9-13 09:01
No, I don't agree.

The battery is being heated up because it's being taxed to the maximum by the  ...

Yes, the heat is due to the high current draw from the motors.

Marginal difference?  By calibrating the IMU at low temperature, it will warm up and be ready to fly sooner.  Someone in another thread said that is because the IMU heater only has to heat it to the calibrated temperature before it is good to go.  True or not, I don't know.  Anyway, it does work.  I waited for a nice cool morning to do my last IMU cal and it was wonderful.  The temperature outside was 37F at calibration.  The next time I flew, it was warmed up and green before I had the app fully ready to go.  It only took seconds.  Before cold cal, it was taking 3-4 minutes.

ag0n Posted at 2015-9-14 12:45
Yes, the heat is due to the high current draw from the motors.

Marginal difference?  By calibrati ...

what greg is saying is that imu calibration, cold or otherwise is not going to be a major factor in the temp of the battery, and i would have to agree with him. test is very easy. turn on p3 and let it sit on your kitchen counter, after 15 minutes see what the temp is, turn off and put new battery in and take it for a flight of say 15 minutes and then see what the temp reads!!

I was only commenting on the "marginal difference" statement.  There is a major difference in warm up time between calibrating cold and hot.  I agree there that there should really be no difference in battery usage, other than perhaps minor "overworking" of the motors from more corrections than normal.