I've been flying the H520/E90 for a few weeks now and have been surprised by battery and other issues as well.
1st-- was a short 4 minute survey that I set a 1" GSD. It flew at 284' and snapped only 18 photos. I did not program an RTL at the end of the mission but it stopped only 20' from my position still at 284'. I switched to RTL and it stayed put. I was unable to make any manual control. Reducing throttle left it hovering at 284' switching to manual or angle did nothing. I had totally lost input and it just hovered beautifully at 284'.
I backed away and reoriented my antennae a variety of ways and nothing changed. So in final desparation, I turned off the ST16+ controller and that prompted a successful RTL.
That's never happed again. Go figure.
I now plan an RTL at the end of each mission and take over manually if desired.
2nd-- on a 7 minute long narrow survey that had 3 1500' legs and another 500' parallel leg and planned at 284'. I started with a full battery that was down to 92% at lift off. It climbed to 284 and departed to the far end of the area to begin the mission. Leg one was smooth and quick. When it turned to begin the second leg I was startled to see the battery had dropped to 50% after the jerky turn maneuvers then off it went. I wanted to be on the ground between 35 and 40%. I invoked RTL to get it back on the ground. It returned promptly and began the tortuosly slow descent. It got as low as 38% but increased slightly as it descended. On the ground it rose to 54% and as I was ready to power everything down it was back up to 68%. That was about what you would expect with such a short aborted flight. If I had ignored the battery indications it would have successfully completed the mission. I packed up and went home to study.
3rd-- With fresh batteries I flew that exact mission again and watched the battery % carefully and I found that it dropped significantly each time it negotiated direction changes (I missed my 3DR's splined curves) . However, as it flew the long straight legs the battery would creep back up. A each turn, it world drop then slowly increase battery percentage on the next leg. It played betweem 46 and 51% on all four legs. then RTL'd and landed with 53% after an moment's rest.
Then I noticed that a FC firmware upgrade existed (Mid Nov) so I applied that. It got real cold here so I limited my flights to shorter tests of other features trying to learn the nuances of Datapilot while searching for splines, POI, and such. After I got home and warmed up the H520 and myself I thought I'd hover the aircraft and see where the autoland cutoff was as I had heard different stories.
I set it in my back yard where I have a 40 x 60' open area. Standing inside the door I launched to a 10' hover at 50%.
I lowered the hover to about 5' (gear still down) so I could see it better and let her hover. Battery now 46%, the aircraft wander in about a 6 to 10' area. I made slight adjustments to bring it back to its takeoff location, 32%. I watched intently to see when it would land. It hovered and wandered a bit, 17% Yikes, that was fast! I looked back outside and it was gone! (double Yikes) I reduced power and in a moment it descended back into view and I landed it straight down very near its launch point at 12%.
Well... That was unsuspected. I figured I'd have it on the ground with at least 25% but the 32/17/12% happened in less than 20 seconds three or four of those were in panic mode.
It was within two or three feet from its takeoff point. I thought it would just land but apparently after flying a while or being adjusted a few times. It decides to go through the whole RTL climb to the minimum return height (mine is 150') before it starts its slow descent for landing. I don't think the battery would've lasted long enough fot that process. I had left the gear down on purpose since I was close to the ground. I can imagine that it would've lifted the gear during its climb and fallen to the ground "camera 1st" without power. Its still very cold so I havent flown since. I still don't know what the firmware update did for me if I flew a whole mission. I've read the whole manual, corrected one or two errors and made a lot of notes. Its typical for what a person writes when he knows everything and doesn't realize what the new user doesn't know.
New commercial pilots making their first aircraft purchase need better documentation. There are a lot of things not discussed.
I think DataPilot is adequate/excellent for new mapping professionals but its week once you start 3D concepts. High wall measurements and 3D modeling will require additional thought processes and piloting skills, but the smoothness (its quiet too) of the H520 and the excellent images from the E90 (note: I've not processed anything yet.). I can manually fly POI circles better that my 3DR Solo does but I let the Solo do its job and its just fine.
I've yet to find how to get Datapilot to take pictures consistantly while flying manualy. I haven't gotten that far yet. So at this point I think I'll have to create a circular path with enought waypoints to take pics with plenty of overlap.
Sounds like a lot of batteries to me.
It raises the question "50% of what?" without smart batteries, this should be more accurate.
C'mon Yuneec. You've done so much so well. Fix this!