I was inspecting and cleaning my Spark just about now, as I do at the end of a flying day. I used 6 batteries worth of flying today. And I noticed this on one of my batteries:

I never had a crash, I'm extremly careful while changing batteries, I store my batteries in a foamed hard case, they don't come in contact with any hard part, no idea what happened. No one used my Spark since I last flown it, and the last time I flew I also inspected and cleaned it so the clip was ok. The only thing I did out of the ordinary today was using Sport mode for the first time ever, about 2 minutes worth. But that can't be it, can it? Is the plastic that easy to worn out? All my batteries are the old type, with small clips.
Anyway, I marked the battery as defective, I won't be using it anymore.

Hi. Thank you for sharing this experience and information with us. Just a reminder to always check all of the parts of our Drone for happy and safe flight.

Thank you for sharing. Very good way to inspect the parts of the Spark.

Wow, that's concerning. I'll be extra vigilant in checking everything. Thanks for the warning.

Great info, I have had my Spark 2 months & read all the stories about ‘ the battery just fell out’. I have been checking they are clipped in properly before each flight but this has prompted me to buy a battery clip just to be sure. Thanks.

On DSC -146, are that scratches left of the clip? How is the bay of the spark looking?

S-e-ven Posted at 2018-7-23 04:01
On DSC -146, are that scratches left of the clip? How is the bay of the spark looking?

The bay is fine, no signs of misuse. I'll check the battery again for scratches as soon as I find my magnifying glass.

It honestly looks like a fracture and not ware. It has sharp edges around the damaged / missing area. Had it been worn the edges would not be sharp, they would be rounded from repetitive use. Maybe you dropped it and didn't realize it? Either way although it somewhat effects AC performance, I always fly with a battery strap.  

Try finding this thingy.

there are some parts available which holds the battery in place. I have not tried it yet, but i've read more battery faillures so it might be something worth checking out?

edit: see post above...

The mistery has been unraveled. My wife crashed it into a cement wall from one meter hight and "forgot" to tell me about it, the cheeky minx.
This is the video of the crash. There's no visible damage on the AC, just the battery latch and the propeller tips. I won't use the battery anymore. The AC flies ok (all functions work correctly) with the damaged propellers, but I think I'll replace all of them soon.
You can't see much on the video, I think the battery is ejected when the propellers touch the wall.