We've all got to start somewhere and make mistakes, just he made it on a more expensive machine than most! Live & learn
Looks like his mistake was to get it into a situation with a critically low battery where the
I2 was needing/trying to land, but was getting confused/stalled by the object avoidance. In that situation, he's probably lost awareness of the exact level of the batteries while trying to work out what was going on with the OA-Radar and his garage. Quite why the
I2 hasn't autolanded itself, I'm not sure, maybe he was unintentionally fighting it with the controls to the point one of his cells went critical and he ended up with power shutdown in the air, maybe it got conflicted with him and with a landing space it didn't think was ok to land in... only he really knows. He mentioned some friends taking their P4 batteries into single %ages - I wouldn't try to take a P4 battery into single figures, and certainly not the
I2!
From my own experience of deliberately flying my
I2 to very low battery levels so I know what happens *before* the brown smelly stuff hits the fan in the field, the
I2 will warn at your low bat warning threshold, you can cancel low Bat RTH and continue flying, It will start shouting again at the critical level, thats why it's set
. Regardless of your set critical level, once it hits 10% battery, it will autoland itself
**. No if's no buts, it'll do it. Unless a cell has a problem and has gone critically low, 10% should still give the
I2 enough juice to land safely. By that time the pilot will be getting plenty of warnings on screen to alert them to the fact things are getting hairy-scarey! I believe from things that are mentioned in the manual (but I haven't tried!) that you can force the
I2 to stay in the air under 10%, but you're going to risk battery cell damage, and the
I2's manual points out the dangers of voltages heading south to 2V etc!
The
Inspire 2 is different to I1 and DJI have made no specific Battery recommendations that I'm aware of yet except for how to store the TB50's. That's 40-65% level, with a full charge-discharge every 3 months. As to starting up the motors to get under 10%, won't work - they shut down at 10% on the ground, and if hovering, it'll land and shutdown. Only way to get the battery under 10% is to leave the
I2 powered on on the ground
** - but you're gonna be waiting some time for those V levels to drop as there isn't a lot of load on them at that point! Yup, I've tried it... and it's not worth the effort
Running-in? Best thing I've found so far is to not thrash the packs for their first few flights to allow them to settle into their new working life, charge fully, fly kindly, and run down to 25-30%. After 4-5 flights, then fly them normally. Day to day use I do from full to around 15%-20%. I watch the voltage after 20-25% is indicated and think about getting home and gear down once under 20% (certainly once the voltage heads and stays around/under 3.5v from memory). My
I2's usually back over the landing pad by 17/18% as I often need the extra hovering time for landing if there're any gusty winds around!
It's worth a quick check of the battery page to see what the individual cells are doing around the low battery warning rth time too - if one or more are dropping against the others then be a bit more cautious. Also pack temperature, the
I2 batts are more exposed and so far haven't seemed to reach much over 30C flying in cold weather (P4 has been up to 50C!), but the voltages will drop suddenly as the pack depletes, and more so if it's cool and liable to cool quickly in cold winds.
Btw, Flying in for first few flights was found out the hard way after a critical voltage drop on it's maiden flight nearly forced the bird down from 200ft, that was after a run downwind, turn into the wind and short flight back upwind, with a full battery. Thankfully the offending cell Voltage recovered enough to clear the enforced landing and It's never reoccurred in the 50+ flights since.
(** update 4Mar2017 - DJI have now changed the Critical Battery Threshold down from 10% to 7% - NickU)
