I found strange behavior of my battery.
One of my battery was charging slowly (compared to other one).
Charging time was about 2 hours (from 50%) and finally all of LEDs remain ON.
According to user instructions LEDs should be OFF when the battery is fully charged.

Should I worry about the battery health?

Battery is about 25 charge cycles and I am using genuine charger.

Thanks

Try a test flight in a safe area ie just let it hover in one spot to see how long the craft will fly for should get close to 30 minutes just hovering.
Then recharge fully again check how long charge takes
Compare these 2 times with other batteries.
If there is a fair bit of difference between them then i would not do normal flights with the suspect battery but would keep it and use for bench top work.
The risk with a suspect battery is that at any point it could fail and this would normally happen during a flight due to the strain place upon it causing your drone to become an expensive falling brick

I will try it next weekend. Great idea.
Fully agree, suspect battery is risky

Please try to discharge the battery to 5% or below, then charge the battery directly via the charger. Please let me know if the issue persists, thank you.

I have a battery that seemed to go bad with one unusually weak cell about a year ago, but I continued using it for so-called bench work and I deep cycled it several times over the months.  Unexpectedly, it seemed to recover over the months and now seems almost normal with the suspect cell only very slightly different from the others.  So, in this case, it seemed to have a second life.  These days I only use it when when flying near the ground just in case but it appears to be normal now.

--Jim

DJI Thor Posted at 2018-1-7 03:20
Please try to discharge the battery to 5% or below, then charge the battery directly via the charger. Please let me know if the issue persists, thank you.

I did it yesterday.

- battery discharged to 15%
- fully charged - LEDs went OFF after charging
- test the battery: hover, 3ft - Battery life time was approximately the same as the other one
- charged battery again  - LEDs went OFF after charging
- flying (over the fields, low altitude)

• Total Kilometrage: 7 km
• Max Distance: 1 km
• Max Altitude: 11.5 m
• Max Speed: 23.23 m/s
  

So, battery seems to be OK

havrosh Posted at 2018-1-8 07:49
I did it yesterday.

- battery discharged to 15%

Did you also notice the charging time for this battery? I would like to know because your 1st floor mentioned it, thank you.

No I didn't notice any difference, charging time was approximately the same.