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Mid-air BT-300 system shut down 'USB CHARGER ERROR' - HELP!

Davo_101

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Last night I flew with my Moverio BT-300s, 2 batteries with Mavic Pro (DJI GO 4.2.14) - perfect flights. Wonderful! I love my Moverios.

Switched to Mavic Air. After 5 minutes of flying I get a message 'USB CHARGER ERROR' and a warning 'system shut down in 30 seconds'. Moments later the system shut down - mid-flight! I was VLOS so no problem RTH. Rebooted and tried again, same message and outcome after 2 minutes. I had 65% remaining battery in the BT-300s and the MA remote was at 98%.

Any thoughts?

TA!
 
If it is working with the Mavic pro tx correctly, it may be something wonky with you MA tx. Very strange issue. Have you tried again with the Mavic pro after the error?
 
Davo,

Were you using an OTG cable? If so your controller is charging the Moverio. I noticed the Moverio LED's were flashing on mine after I finally got 4.2.14 loaded and running and connected via an OTG cable. I did not run mine for an extended period of time only one short flight. I wouldn't think the controller is charging at a high rate but I'll bet there is a temperature sensor on the battery that watches the battery temp when charging. I know that when in use the Moverio microprocessor gets quite warm. So I wonder if the high temp of the micro was heating up the battery sensor causing a false over temp of the battery. If this is the case we will have to figure out a work around. I'm thinking we may have to cut the 5 volt wire in the OTG cable to keep the controller from charging the Moverio. We may have to fool the host by putting a load resistor on it after cutting the wire.

Did you by chance feel the case of the Moverio to see how hot it was? I have read several people are complaining about the touch pad getting hot. Also might mount a small fan under the Moverio to help cool it.

You mentioned you flew at night and got 2 flights on your MP. That should have been at least 30 minutes of flight time. I wonder how much sooner the charge error would occur if you were flying during the day with a higher outdoor ambient temperature?

~Bill
 
If it is working with the Mavic pro tx correctly, it may be something wonky with you MA tx. Very strange issue. Have you tried again with the Mavic pro after the error?

Not tried again - after multiple cycles of reboot followed by this error I switched operations to fly the air with my trusty Samsung Note 3. I may get a chance to try again later and will report back on findings. Thanks for your support.

Forgot to mention - I have flown the MA with BT-300s several times previously without problems so unlikely to be an MA TX problem. Can you get confirmation if this error message is generated as the result of battery charging while over temperature?

David
 
Last edited:
Davo,

Were you using an OTG cable? If so your controller is charging the Moverio. I noticed the Moverio LED's were flashing on mine after I finally got 4.2.14 loaded and running and connected via an OTG cable. I did not run mine for an extended period of time only one short flight. I wouldn't think the controller is charging at a high rate but I'll bet there is a temperature sensor on the battery that watches the battery temp when charging. I know that when in use the Moverio microprocessor gets quite warm. So I wonder if the high temp of the micro was heating up the battery sensor causing a false over temp of the battery. If this is the case we will have to figure out a work around. I'm thinking we may have to cut the 5 volt wire in the OTG cable to keep the controller from charging the Moverio. We may have to fool the host by putting a load resistor on it after cutting the wire.

Did you by chance feel the case of the Moverio to see how hot it was? I have read several people are complaining about the touch pad getting hot. Also might mount a small fan under the Moverio to help cool it.

You mentioned you flew at night and got 2 flights on your MP. That should have been at least 30 minutes of flight time. I wonder how much sooner the charge error would occur if you were flying during the day with a higher outdoor ambient temperature?

~Bill

Thanks Bill - yes the Moverio got hot, but not any hotter than usual in normal use as far as I can tell from touch alone. I was using a high quality OTG USB connected to the bottom port on the TX. It was late evening rather than dark of night, but it had been an exceptionally warm day in the UK. I suspect that you are on the right track here. Total flight time with MP was 40 minutes of fun followed by 40 minutes of frustration with the MA. The Epson engineers should be able to tell us if this error is caused by battery overheating and suggest a fix. I purchased the BT-300 for their compatibility and stability with DJI - I am having fun with them when they work, but this does not inspire confidence. Not sure how I would mount/power an external fan, and cutting the cable and adding a load resistor sounds challenging and should not be necessary.

Thanks again - David.
 
Hi David,

I was talking about the fan idea and incorporating it in a new 3D printed mounting bracket with someone earlier. A small 5 volt fan mounted directly under the Moverio to move a little air would help. Blade guards could also be part of the 3D design. Power could be supplied by the controllers USB port. A special cable would be made that provides power for the fan and still pass data for the glasses. But..... I think we are getting ahead of ourselves. Lets see what Epson has to say as there does appear to be a heating issue.

You might want to try flying again without using an OTG cable and watch for the same warning.

I too love the Moverio BT-300's

~Bill
 
Hi David,

I was talking about the fan idea and incorporating it in a new 3D printed mounting bracket with someone earlier. A small 5 volt fan mounted directly under the Moverio to move a little air would help. Blade guards could also be part of the 3D design. Power could be supplied by the controllers USB port. A special cable would be made that provides power for the fan and still pass data for the glasses. But..... I think we are getting ahead of ourselves. Lets see what Epson has to say as there does appear to be a heating issue.

You might want to try flying again without using an OTG cable and watch for the same warning.

I too love the Moverio BT-300's

~Bill

How do I connect the BT-300s to the TX without an OTG? I know I can connect to the A/C hotspot using wifi direct from the BT-300 but I think that would give very short range.
 
WiFi would be the only way. However the problem (we think) is an overheating when the Moverio is on and and connected to the controller via OTG. The test outlined below does not require the drone to in the air. A simple test might be to power everything up in a static condition (rotors not spinning) including an OTG cable and just let it cook. Place a small fan near the drone to prevent overheating. Note the start time and watch for the USB charger error. Should the error occur note the time. Next step; recharge everything using regular chargers. connect the Moverio using WiFi this time and no OTH cable. Note the start time and let it run. In this test condition I doubt you will see the USB CHARGER ERROR. Try to have the ambient temperature about the same as when you first experienced the error.
 
Here is some interesting info on disabling USB charging on the DJI form.

Disable USB charging?

If you can disable the USB charging your USB CHARGING ERROR should go away.

I'll keep looking.
 
rocketman, were you having the same USB charging error?

David, is there an option to connect data only when you connect?
 
@bmelody - Thanks for all your comments. No way do I want to root a 3 month old device to disable charging. If it can be done with software Epson or DJI should release a utility (not rocket science) or at least a notice to consumers warning about this issue. No option for data only when I connect. I won't have a chance to retest until tomorrow.

@rokcetscientist - if you had the same problem what were the circumstances, and please can you please confirm if constant or intermittent? If its hardware it should be under warranty but I'd like to avoid the downtime replacing them if there is an alternative solution.

@EpsonMoverio - any chance you can get some feedback on this topic from your Engineering team?

Thanks!
David.
 
Same error—during mid-flight! I contacted Epson Support and told them this was a dangerous situation.

My case was immediately sent upstairs and I was authorized a new replacement.

This is my third BT-300. First one received from Amazon was not new and was sent back. Its replacement (the second unit) was new but started to automatically power down after the USB Charging Error message. I'm hoping this third unit direct from Epson is the end of the story.
 
I am also not willing to root my glasses either. It does sound like something Epson can correct with new firmware.
 
Same error—during mid-flight! I contacted Epson Support and told them this was a dangerous situation.

My case was immediately sent upstairs and I was authorized a new replacement.

This is my third BT-300. First one received from Amazon was not new and was sent back. Its replacement (the second unit) was new but started to automatically power down after the USB Charging Error message. I'm hoping this third unit direct from Epson is the end of the story.

Thank you - was this with MA or MP?

I don't seem to have a problem with MP, but I need to do some more testing to really confirm. Just retried from a cold boot with MA and it failed after about 12 minutes - BT-300 got hot - was indoors streaming video from the drone at room temp so it's not weather related.
 
So more information - I sideloaded Ampere to see charging rates - quick test on BT-500 MP = 220mA and MA = 330mA - not sure if this difference is related to the residual state of charge in the controllers or something else. Interestingly same test plugged into Note3 showed steady 450mA for both controllers. I don't know enough about batteries and chargers to understand what is going on.
 
I did some experimenting with my BT-300's and found the charging current to be approximately 190mA with my Spark using an external DVM. I did not test with my MP other than to see if it would connect. It did and it was also charging but I didn't measure the current. I tried several things with limited success. I found a video where you cut one of the wires in the cable to eliminate the voltage supplied by the host (controller) so I tried it. Cut the red wire (Vcc, 5VDC) it does stop the charging but also kills the USB communications. Apparently the BT-300 uses a USB chip that requires or senses the +5 VDC coming from the host. Reconnected the red wire and cut the black wire. This killed the charge and allowed the data to continue. I thought this might be a solution but unfortunately after about ~30 seconds I received a "CHARGER ERROR, SHUTTING DOWN IN 30 SECONDS" . It did indeed shut down. Next I tried a 30 ohm resister is series with the 5 VDC. This lowered the charge current to ~22mA which would reduce the heat generated but it also gave me the same charger error but after about minute or so. I did not try a lower value resistor that would increase the charge current as it may only extend the time before the error occurs. I do not want the BT-330 to shut down during flight however I may experiment to see if there is a happy medium. I searched the settings menus looking for some sort of control for USB charging on/off or setting the charge current but did not find any such control. I also searched for an app that could be installed without rooting to no success but I will not give up. DJI could implement and charge current limiter in their software but that is same as installing a series resistor and that is a spooky solution as indicated above. The best solution will have to come from Epson where they give us an option to shut down the charge circuit until the battery reaches a preset level of discharge. Allowing the BT-300's to switch the charger back on at a low battery level would/could prevent a shutdown due to a very low battery.

The fact the charger is charging and at a fairly high rate is more than likely the reason people are complaining about the excessive heat felt on the touch pad when using an OTG cable. EPSON if people are returning units due to overheating here is a possible fix to this situation. Get your software group to give us some control over the USB charging ASAP. It would be a win win for everyone!

Moverio engineering people, please respond here with a comments as sending an email to customer service is a complete JOKE!!!! All I get are standard canned responses. You have a great product, solving these PITA issues will make them even better.

~Bill
 
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Bill - thank you for your feedback and hard work. it's good to know that I am not alone with this issue. I hope we will get some feedback from @EpsonMoverio soon. I love my Moverios but don't trust them anymore.
 
My pleasure David,

I re-ran my experiment using an external power supply this time and discovered that a 30 ohm resistor in series with 5VDC Vcc will indeed reduce the charge current. What threw me for loop yesterday was I expected the LED's on the Moverio's to stop flashing but still communicate. When I lowered the Vcc to a point where the LED's did stop flashing the BT-300's USB port would shut down and disconnect from the controller. My mistake was the LED's will flash whenever the BT-300 detects a voltage above ~ 3.5 VDC on the Vcc line. It is simply telling you there voltage present on the connector. The nominal Vcc coming from my controller with a full charge was 5.14 VDC. At this voltage (full charge) the charge current was ~450 mA. At 450 mA my BT-300's began to heat up. Not hot, but getting warm. After several iterations I finally settled on a 30 ohm resistor and a charge current of 22 mA. With a higher value resistor I could even get the charge current down to 0.0 mA but I wanted to be sure the BT-300's always have enough voltage so as not to connect. I let the system run for almost an hour and the BT-300 remained cool to the touch. I know this is a work-around solution but its the best we can do without rooting. Hopefully Epson will develop a software fix SOON.

This is a simple thing to do. Take which ever cable and cut a 2 inch slit in the outside jacket being careful not to cut into the wires inside. If there is a braided shield try to spread it so you can gain access to the foil shield. Remove the foil shield and discard. There should be 4 wires inside the cable. A red, a black, a white and a green. I would use a volt meter and verify the Vcc is the red wire and the black is the ground. Just make a voltage measurement between the black and red and you should read 5 VDC. This is just to verify whomever made the cable followed standard color code. It is possible they did not. Then simply cut the red wire and insert the resistor. One red wire to one side of the resistor and the other red wire to other side of the resistor. Use heat-shrink to insulate your connections making sure the neither side of the resistor can come in contact with the braided shield.

I can do a picture if you like, just no time tonight.

I have half a notion to make a simple connector with the resistor already installed and offer it for sale. There are lots of android users complaining about their phones getting hot due to charging.
 
I have half a notion to make a simple connector with the resistor already installed and offer it for sale. There are lots of android users complaining about their phones getting hot due to charging.

Brilliant - I would be very happy to be your first customer ...
 
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