I'm a beginner that has been practicing twice a day with my Spark and believe I've progressed beyond novice stage. Over time I found that connecting the RC to my Samsung S5 phone through an OTG cable gave me the best performance. I could easily send my spark out 2500 ft at 250 ft elevation without losing connectivity or strength of image signal. After reading several instances of Spark falling from the sky, particularly after changing the battery, I read a suggestion that I should refresh the latest firmware with each battery installed in the Spark. I did so. Suddenly, there is a great lag while using the OTG cable - significant enough that I'm not able to fly using FPV. I've tried everything I can think of to get rid of the lag with no success, however, when I link the RC and phone using a wireless connection the lag is no longer an issue. But now I'm back to the issue of weak image transmission signal at around 1000ft distance (the reason I went to the OTG cable in the first place). I've checked firmware and everything is current and presumably not changed, but it seems that refreshing the firmware with each battery installed was the genesis of my problem.

Any advice?

Try killing (shut down) all the other apps running in the background on your smartphone.  Also kill the GO4 and restart it.  I've found this to be helpful in reducing video feed issues.

Hi, what do you mean by refresh the latest firmware with each battery installed? i have latest firmware on spark and rc and used the both batteries with no problems?

Hi, what do you mean by refresh the latest firmware with each battery installed? i have latest firmware on spark and rc and used the both batteries with no problems?

realstreetuk Posted at 2017-7-20 09:32
Hi, what do you mean by refresh the latest firmware with each battery installed? i have latest firmware on spark and rc and used the both batteries with no problems?

Saw a long message from a Phuong Do yesterday that included the following: "--> If you bought extra batteries that come separated with your combo, please plug it in, connect to DJI Assistant 2 on PC and refresh the firmware with that battery." I didn't realize the battery included any firmware, but figured it wouldn't hurt anything to follow the suggestion - I was wrong on that count.

Hi Sliderul, firstly, just to verify, you had updated all your firmware including batteries, RC and the drone body, right? Sometimes the firmware version with a +/- mark behind means the upgrading incomplete. You can check the version by this way: power on the drone, RC, app and enter device---upper right icon---general----about. The latest FW of the craft is V 01.00.0400, V 01.00.0100 for RC, please check.
Like Hummingbird.UAV mentioned above, please try to shut down the other app of the device, or switch the phone to the airplane mode, especially, Bluetooth or some other interference may also contribute to the lag of the image transmission.
About the weak image transmission signal, I could also suggest that you can try another place to fly to test if it is the environment should take the responsibility for it.  
Besides, the connection between the Spark RC and the mobile device via OTG cable has not been fully tested, so I would suggest that you use it with caution.

DJI Thor Posted at 2017-7-21 00:05
Hi Sliderul, firstly, just to verify, you had updated all your firmware including batteries, RC and the drone body, right? Sometimes the firmware version with a +/- mark behind means the upgrading incomplete. You can check the version by this way: power on the drone, RC, app and enter device---upper right icon---general----about. The latest FW of the craft is V 01.00.0400, V 01.00.0100 for RC, please check.
Like Hummingbird.UAV mentioned above, please try to shut down the other app of the device, or switch the phone to the airplane mode, especially, Bluetooth or some other interference may also contribute to the lag of the image transmission.
About the weak image transmission signal, I could also suggest that you can try another place to fly to test if it is the environment should take the responsibility for it.  

Thanks for the suggestions. I checked FW and everything is current with no +/- mark. I'm using an old Samsung Galaxy S5 phone that I've dedicated to flying the Spark. I've removed most apps altogether and I shut down wireless and bluetooth before connecting through the OTG cable. Everything was working perfectly before I refreshed (not update) the Spark FW. It seems that the refresh either changed a setting that I can't find or there was some subtle change in the FW that impacted the OTG connection without changing version number.

There is an option to backwards refresh to a version that was stable. This is common with the Phantom pilots who have issues. Some don't bother with them at all when they get a good stable and solid version. I have had my Spark for about 3-4 weeks now and not updated or refreshed anything. On start-up it states latest version etc so good so far. As long as the version is as DJI THOR states above. Just out of interest, have you tried the same with an IOS device if you have one - iPhone or iPad. A lot of peeps report that IOS is more stable than Android.

I appreciate the feedback and understand your suggestion, but it wasn't a version update that seem to cause the problem, I refreshed the version I had (for a dumb reason). I updated my FW almost immediately after receiving the drone, so I don't know that a previous version is more stable - but it certainly won't hurt to give it a try. I don't have any IOS devices to try, but I do have a different phone and will try that as well. I can still enjoy the drone using the wireless connection with the RC, it's just not as good as the OTG connection WAS before I refreshed FW.

If you use the OTG cable can the go 4 app get the satellite data while flying? When I’m flying connected to RC I get a pop up telling me it needs cant retrieve info.

gnuDroneUser Posted at 2017-7-22 19:34
If you use the OTG cable can the go 4 app get the satellite data while flying? When I’m flying connected to RC I get a pop up telling me it needs cant retrieve info.

I use the OTG cable with the spark but i didn't  see any satellite data missing during flight. But i'm not quite sure what you mean with satellite data ?? I do have GPS and the map is updating correctly. Anything else i should look at?

Hi, i have same issue using Spark+RC+OTG+Iphone. After 100-150m its get laggy and lost connection, also with 70m verticaly. One thing i was trying to update RC but i cannot find how. In DJI GO app when im checking everything is fine, but DJI Assistant cannot find RC controller.

Beretheon Posted at 2017-7-24 03:13
Hi, i have same issue using Spark+RC+OTG+Iphone. After 100-150m its get laggy and lost connection, also with 70m verticaly. One thing i was trying to update RC but i cannot find how. In DJI GO app when im checking everything is fine, but DJI Assistant cannot find RC controller.

To the best of my knowledge there is no official FW update available for the RC,  there is a Beta version that others on this forum have been testing/using.

Sliderul Posted at 2017-7-22 13:10
I appreciate the feedback and understand your suggestion, but it wasn't a version update that seem to cause the problem, I refreshed the version I had (for a dumb reason). I updated my FW almost immediately after receiving the drone, so I don't know that a previous version is more stable - but it certainly won't hurt to give it a try. I don't have any IOS devices to try, but I do have a different phone and will try that as well. I can still enjoy the drone using the wireless connection with the RC, it's just not as good as the OTG connection WAS before I refreshed FW.

I do not have an OTG cable yet but when using wifi i never had any problem with the image transmission besides about a 1/4 second delay. when i refreshed the, already updated firmware, the drone worked perfect...until i used the other battery(i refreshed both) the drone was less stable and the image transmission was horrible so i tried to refresh the firmware again on that particular battery. i haven't had the chance to try it yet but hopefully i will this week.

Erwin Beckers Posted at 2017-7-22 23:13
I use the OTG cable with the spark but i didn't  see any satellite data missing during flight. But i'm not quite sure what you mean with satellite data ?? I do have GPS and the map is updating correctly. Anything else i should look at?

When the OTG cable was working without any lag, I had no issue with satellite data (I assume you're referring to the GPS satellites). Before I ran into the lag issue, the OTG connection seemed to be the way to go.

Beretheon Posted at 2017-7-24 03:13
Hi, i have same issue using Spark+RC+OTG+Iphone. After 100-150m its get laggy and lost connection, also with 70m verticaly. One thing i was trying to update RC but i cannot find how. In DJI GO app when im checking everything is fine, but DJI Assistant cannot find RC controller.

I switched to another Samsung phone and the lag disappeared so I was convinced the issue was with the phone; however, later that same day I decided to give the system a more thorough test with the new phone and the lag reappeared. Now I don't know if the issue is the RC, the phone or the Spark.

When you first make your connection between phone and RC, whether OTG or wireless, there is a message in the upper right corner of DJI Go 4 that confirms your FW is current. If not, there is a procedure to update the RC which I saw somewhere on the forum (sorry I can't be more specific).

Sliderul Posted at 2017-7-24 07:51
I switched to another Samsung phone and the lag disappeared so I was convinced the issue was with the phone; however, later that same day I decided to give the system a more thorough test with the new phone and the lag reappeared. Now I don't know if the issue is the RC, the phone or the Spark.

When you first make your connection between phone and RC, whether OTG or wireless, there is a message in the upper right corner of DJI Go 4 that confirms your FW is current. If not, there is a procedure to update the RC which I saw somewhere on the forum (sorry I can't be more specific).

Yes, in DJI GO4 everything is up to date. Today i will try procedure of changing wifi to 2,4Gh as here: http://forum.dji.com/thread-104320-1-1.html
im a European user so i have poorer signal from RC