Battery cell error ?

Mjonesy758 · May 29, 2018

Hi I have been out of he drone game for around 7 months put the drone away in October weather,work,toddler,new baby. All kept me from flying (i know excuse). Got the mavic out about 2-3 weeks ago and charged everything up and took it out one battery off the bat had a bad cell. Down to two battery’s today I got it out and another one was bad. Down to one I have the battery’s set to discharge after 5 days they both have less the. 30charge cycles on them combine I take them off the charge when they are done or within a hr of them bing done I don’t babysit them but don’t let them set all night. They set in a hard case and a temp controlled environment never into hot or cold temps. My question is am I doing something wrong? Did DJI make a bad batch of battery’s? Do I just need to make time and fly more. Should I discharge them down to nothing to store them? I was told they don’t like to be fully charged or total empty. Any help out be appreciated my drone is a lil over a year old.

ChrisW81 · May 29, 2018

Did you store the batteries within the 30ish% range?

RayOZ · May 29, 2018

Depends on the % when you stored it. 7 months is a long time. Batteries are made up of chemicals, which I have no idea what happens inside when it's left alone for so long. I am pretty sure they deteriorate over time, whether in use or not. That's why battery warranty is only 6 months. Maybe the connections have corroded.
Anyone know if keeping battery cool (in the fridge?) would prolong battery life? Someone told me he stores new/spare batteries (alkaline ones) in the freezer so they store longer, until he needs to use them. Won't do that with smart batteries as they have electronics inside.

ChrisW81 · May 29, 2018

RayOZ said:
Depends on the % when you stored it. 7 months is a long time. Batteries are made up of chemicals, which I have no idea what happens inside when it's left alone for so long. I am pretty sure they deteriorate over time, whether in use or not. That's why battery warranty is only 6 months. Maybe the connections have corroded.
Anyone know if keeping battery cool (in the fridge?) would prolong battery life? Someone told me he stores new/spare batteries (alkaline ones) in the freezer so they store longer, until he needs to use them. Won't do that with smart batteries as they have electronics inside.

From my understanding, there’s a YouTube video somewhere with an explanation, LiPos should never go into fridge. Just stored at around 30ish% for storage. I think that’s about the 2nd LED Solid or 2nd LED flashing. DJI handbook would clarify that.

I’ll try to find that video and post it here so others can take what they want from it.

ChrisW81 · May 29, 2018

Here is that video. It’s rather long but the info presented seems to be the consensus from most everything I had read about.

Gray52 · May 30, 2018

He never mentioned about Battery break in period. With a new battery I fully charge it, fly it down to about 65% leave it to cool, then recharge then drop the % to 50%, I do that 10 times then take it down to what ever % you want.

Mjonesy758 · May 30, 2018

They may have been stored more then 30% but I had it set to drain down after the 5 day mark so even if I am not flying I should charge them drain them down repeat not just let them drop to 30% and leave them?

Mossiback · May 30, 2018

I have read other posts where a long-unused battery reported uneven cells but after a few drain/recharge cycles they evened up.

KDan · May 7, 2019

This is an increasingly common problem with Mavic Pro batteries. Full discharging/recharging does NOT help. In fact, it can make the problem worse. I've fixed two of my own Mavic packs and one for a friend. It does require a bit of work. See this thread that I posted last year... Balance plug for Mavic pack