It seems I read somewhere you are supposed to run your batteries down completely once in a while.  Is this true?   If this is needed do you just leave it on until it's fully drained? I have a Spark and a Phanom 3 4K Thanks

I don't know the science behind this. With lithium ion batteries its good to get a full charge cycle once a month or so.

Illmaticz Posted at 2018-1-1 08:49
I don't know the science behind this. With lithium ion batteries its good to get a full charge cycle once a month or so.

You use to do it with camera batteries. It erased the batteries memory. But with the modern batteries, you don't need to do it anymore  

with LiPo batteries you do NOT want to run them down below 3.0v per cell.. us having a 3 cell battery would mean not less than 9v total.

It damages the cells to drop below 3v per cell.  I would imagine 0% on the sparks battery would actually be limited with a lipo cutoff meaning the lowest it will allow voltage to drop would be roughly 3v per cell.

Discharge to 5% every 20 flights  (or cycles) is what I've been doing and they work just fine.
Warranty is for 200 cycles in general.
I fly to 10% where it will try to force land, then hold left stick up accordingly to discharge the remainder, down to 5%.
Let them "rest" before re-charging .
Data on batteries health can also be seen on some apps, like airdata.com  .

Must to add to the mayhem...

Apparently, from what I've read in forum posts, the more-modern DJI batteries are set up so that 0% is not actually 0%.  This makes it very difficult to get your battery down below the catastrophic 3.0v cell level.  This also explains how sometimes you might read that 5% is an appropriate deep discharge level, whereas it used to be 8% a few years ago.

No do not run them dead dead it harms them good videos on YouTube on this with drone valley

Kind of a side-issue to the OP's, but am I right in thinking if you haven't flown in a week or so (we've cr@p weather here for a few weeks), you should re-charge batteries/RC etc?

Mark The Droner Posted at 2018-1-14 07:01
Must to add to the mayhem...

Apparently, from what I've read in forum posts, the more-modern DJI batteries are set up so that 0% is not actually 0%.  This makes it very difficult to get your battery down below the catastrophic 3.0v cell level.  This also explains how sometimes you might read that 5% is an appropriate deep discharge level, whereas it used to be 8% a few years ago.

this seems to be true. I usually take my batts down to about 35-30% as it's reported in the telemetry, but the cells are around 3.8v resting. On a LiPo, that normally corresponds to a little over 50% total capacity left in the batt.
On all my other regular LiPos, I put in just under half of the stated mah-capacity of the batt if I run them down to 3.8v.

So yes the smart logic in the DJI batts probably gives more of a usable-without-destroying-me percentage left rather than the total capacity period. I've only gotten down to about 10% one time and the resting voltage was still around 3.7v, which is fine....

nicely done - thanks for sharing.