Total BT 300 black out warning.

[John Gowland]

This has happened to me once before, but it happened in Phuket a few days ago.
The glasses control unit cannot take the heat especially when the humidity is high.

It happened a few months ago at home in Perth when the temperature and humidity was not very high.
This time it was scary. I was keeping the BT control unit cool by wrapping it in a frozen cooler pack for a few minutes (so it didn’t get to cold and become unstable) between battery changes.
Soon after take-off it died without warning, nothing, black screen.

I was flying a Mavic Air so I had no readings what so ever. Also, I took off through a small hole under a jungle canopy. I could hear the bird, so I know it was fairly close but could not guess where it was.

What you do when you experience a BT 300 total blackout.
1 stay cool
2 remove the BT controller from the MA controller
3 connect a prepared phone to the MA controller you don’t have to restart the MA controller.
4 find your bird in the sky from the screen on the phone and bring it home.
Finally clean up the mess you created in your clothing.

Despite its issues I still love the glasses.

But Epson fix the darn heat/humidity issue.

 

[ksmusa]

Wow! That’s awful! I have not experienced this but will be sure to let you know if it happens to me. I have however noticed that the unit can become quite warm when using the DJIGo4 for app for an extended period of time.

 

[bmelody]

Hi John,

Very sorry to hear of your overheating and shutdown issue. We have been chasing a shutdown issue as well. See, Mid-air BT-300 system shut down 'USB CHARGER ERROR' - HELP!. However in our case the shutdown was preceded with a "USB CHARGER ERROR" unit will shut down in 30 seconds. We thing we might know what is going on. My issued started after upgrading to DJI GO 4.2.14 and using an OTG cable with my Spark. Prior to the software upgrade I had to use WiFi to connect to the Spark as there was no OTG support for the Spark. After the upgrade DJI GO now supports OTG for the Spark. Here is the rub. When using a cable the DJI controller now has the ability to charge the BT-300's. Charging the battery is adding additional heat and when added to the heat generated by the uProcessor we have a overheating condition. We have done several experiments and I truly do believe this to be an issue. Please read the thread mentioned above.

~ Bill

 

[Davo_101]

I now have an emergency phone ready to take over in th event of a shut down. Sadly I can't rely on the BTs at the moment. I expect more for the premium price we paid these glasses.

 

[John Gowland]

I agree Davo_101 but when they are working the glasses are just stunning.

 

[John Gowland]

Bill you are probably right. However I really think it is not a cable/software issue when the heat and humidity get serious. They simply have to put a cooling device into it with some software upgrades.
As i have just mentioned elsewhere when the glasses are working they are just heaven.
When I cant avoid people they are always curious and I let them see through the glasses. Every jaw ends up on the floor.

 

[bmelody]

Hi John,

I have proven there is a substantial increase in the temperature of the BT-300 when connected to the controller. Davo_101 and I are using an app that monitors the battery charging current and temperature called Ampere.

During one of my tests the battery temperature was greater than 47 degrees C and at that point the (Ampere) software in the BT's reported "Battery Over Temperature, Charging Discontinued" The battery disconnect due to being over temp is a Android built in safety device in all androids including the BT's.

Here is a simple observation you can make. Fully charge all your devices. After booting up all devices just prior to take off take a look at the BT's 3 LED's. They will be a solid blue in color indicating the BT's battery is fully charged. Fly to 15 to 20 minutes (maybe slightly longer) then take another look at the BT's 3 LED's. I'll bet they are now flashing indicating the BT's battery is being charged. The charge current from your controller is providing 450 mA of charge current. I measured the current using an external DVM as the Ampere app is looking at total device current and I was only interested in the actual charge current. The BT's nominal run current is around 750 mA static. When the Go app is running the current increases to 1000 to 1200 mA depending on the work the processor is doing. Adding to that an additional 450 mA of charge current will increase the heat dissipation by approximately 50%.

There are ways of controlling the charge current in an android device however it requires rooting the device. At this point, I (and others) are not willing to root the BT's. We can only hope Epson will provide a firmware upgrade that will allow some control over the charge current. It may also be possible DJI could limit the controllers output as there are many other android phone users complaining of there phones getting hot when flying.

I hope Epson is reading about people having overheating conditions and in your case a total shutdown. At least Davo_101 and I had a 30 seconds of warning.

I agree the BT's are OUTSTANDING! Lets hope we have a solution soon.

~Bill

 

[John Gowland]

Oh ok bmelody I will take your suggestion on board.
Don't worry Epson are watching these threads very closely, its their business to do so.
I agree we have enough variables to deal with, with out introducing rooting stuff.
I am waiting for a P4P v2 and hope with OcuSync I can have both the glasses and a phone connected at the same time, but suspect this will not be possible on one r/c controller.
At least we know we can rip out the glasses controller and stick in a phone mid flight to get home. I was so relieved when that worked. Bird was somewhere above a jungle canopy and I could not see it to get it down.

 

[bmelody]

Hi John,

I can only imagine the panic that sets in at the moment. But if we let go of the sticks let the bird hover while we change devices all will be good. Easy to say, hopefully I would have the ability to override the panic. One of the first things I learned during pilot training was. The first thing to do in an emergency is nothing, then evaluate the situation, then act. Again easy to say.

Now it is time to plant some 15 shrubs my wife purchased, oh joy. I'd rather be flying!

~Bill

 

[John Gowland]

Well if she goes out to find you and only sees a few planted, one half planted and a trowel on its side and the weather is good, she will know what you are up too.

 

[bmelody]

Amen!

 

[Flycaster]

All you have to do to stop the RC controller from charging the Moverio controller is to cut the +v line on the cable/. Leave the ground for that circuit intact, and also, don't cut the data and data return line...

 

[bmelody]

Hi Flycaster,

I attempted to do that very thing. I even posted the results somewhere on this site. When you totally remove the Vcc as you suggested the Moverio controller will not allow DJI GO 4 app to start. I forget exactly what was going on. I Think the USB port on the Moverio is powered by the OTG cable. One thing I don't remember if I tried would be to have a switch in the Vcc line. Get everything up and running then switch off the Vcc. I did try installing a series resistor in the Vcc line, a 20 ohm or there about to limit the current flowing. Again the results are posted. The problem with the resistor was if the current flowing gets too low (actually the Vcc gets too low ) the Moverio goes into a "USB CHARGER ERROR" and shuts down in 30 seconds. After a bunch of bench testing I came to the conclusion there is too much internal heat as the required current with everything running is ~1400 mA. If memory serves me correctly I think the BT's actually ran cooler when 450 mA was being provided from the DJI controller. I think the battery pack when delivering 1400 mA of current get hot on its own. I even thought of disconnecting the internal battery and using an external source but life got in the way. who knows I may attempt the external supply idea some day.

I love bt BT-300's just do not have 100% trust in them. I think the ideal solution Would be to have BT300's or BT35E connected to a CrystalSky of Nvidia K1 via HDMI. This would eliminate Moverio controller altogether.

Bill

 

[John Gowland]

"All you have to do...."
So Fluycaster and bmelody I have the Mavic 2 zoom and bt 300 glasses in front of me. What do I do?
Pray tell, please?
I flew this morning for an hour and no problem whatsoever. About 25c and
I know it's the combination of still air, high humidity, and high temps because I have flown in high dry temps with a breeze.
The BT 300s, as it is stands, is miles above any other device, no contest and I am bemused why people stick to phones and tablets of any kind. They don't shut down without notice now they just start to lag and you have time enough to get the bird back. Even when they did shut down you could exchange for a phone within a minute to get it back.

 

[bmelody]

Hi John,

Everything I tried really didn't help a lot. There just too many things that develop heat in a tight package with poor cooling. The best improvement I ever made was a small fan mounted under the controller and shield it from the sun.

If memory serves me cutting the red Vcc wire in the OTG did not work. The USB port on the Moverio requires the Vcc voltage to operate. Without the Vcc the Moverio will not receive any data from the DJI controller.

~Bill

 

[John Gowland]

Thanks Bill, much appreciated. We should not complain as much there has been so many improvements over the original software packages which bombed out at low temps and low humidity.
The parallel I suppose would be to take your Mavic and BT glasses to the south pole in high winds and complain, "My glasses won't work with the Mavic 2."