Acceptable Cell Voltage Variance?

fhagan02 · Oct 5, 2015

I've poked around the web but can't find a solid answer on this. (Or perhaps I'm just not smart enough.) I know the cells should be even but don't have to be exactly the same voltage. Noticed this reading on one of my batteries...see attached. This battery has the most deviation of equality out of all my batteries. So.... does this look like a battery that's on it's way to bitting the dust and dangerous to use? Thank you.

bobmyers · Oct 5, 2015

fhagan02 said:
I've poked around the web but can't find a solid answer on this. (Or perhaps I'm just not smart enough.) I know the cells should be even but don't have to be exactly the same voltage. Noticed this reading on one of my batteries...see attached. This battery has the most deviation of equality out of all my batteries. So.... does this look like a battery that's on it's way to bitting the dust and dangerous to use? Thank you.
View attachment 32821

Have you cycled it down to 8% yet and recharged it?

fhagan02 · Oct 6, 2015

bobmyers said:
Have you cycled it down to 8% yet and recharged it?

Did that tonight. Charging now. I'll check when it's full. Thanks much.

Nstrong48 · Oct 6, 2015

let me know how it goes, I'm in a similar situation with a battery only 4 charges

MattyDread · Oct 6, 2015

I was in a similar situation with one of my batteries - when I did the 20 cycle & depleted to 8-10% (not under load) it sorted out the levels & made me happy

fhagan02 · Oct 7, 2015

bobmyers said:
Have you cycled it down to 8% yet and recharged it?

Here's the reading after depleting to 8% and charging back up. 3 cells are now close as they should be, with the 4th a little higher. (Lost 1% Battery life also.) My other bats don't vary more than .03 so since there's still quite a variance between 1-3 and 4 is this reason for concern? Overall Voltage now says 17.0V on a 15.2V battery! Is that a reason to be concerned?!

Sorry to be such a panic nerd but I just got this thing back from 2 back to back RMA's. Wanna be sure all is good when I fly. I should probably just trash the battery. That's a sure way. LOL

Nstrong48 · Oct 7, 2015

Pretty sure my batteries say 17v + as well

fhagan02 · Oct 7, 2015

Nstrong48 said:
Pretty sure my batteries say 17v + as well

Good to know... thank you.

bobmyers · Oct 8, 2015

fhagan02 said:
Here's the reading after depleting to 8% and charging back up. 3 cells are now close as they should be, with the 4th a little higher. (Lost 1% Battery life also.) My other bats don't vary more than .03 so since there's still quite a variance between 1-3 and 4 is this reason for concern? Overall Voltage now says 17.0V on a 15.2V battery! Is that a reason to be concerned?!

Sorry to be such a panic nerd but I just got this thing back from 2 back to back RMA's. Wanna be sure all is good when I fly. I should probably just trash the battery. That's a sure way. LOL
View attachment 32983

They would read 17.2 if all four cells were fully charged. Cell no 4 is slightly over charged, ( max charge per cell should be 4.3) which is strange if the Smart Battery balancing circuit let allowed one cell to over charge. It would show 100% cell capacity if all four cells were equal at around 4.28 when fully charged. Those 3 lower cell voltages are bringing that down to 98%.
I would just monitor those voltages, before and after every flight to make sure that one of the cells didn't start to drop significantly from the others.

fhagan02 · Oct 8, 2015

bobmyers said:
They would read 17.2 if all four cells were fully charged. Cell no 4 is slightly over charged, ( max charge per cell should be 4.3) which is strange if the Smart Battery balancing circuit let allowed one cell to over charge. It would show 100% cell capacity if all four cells were equal at around 4.28 when fully charged. Those 3 lower cell voltages are bringing that down to 98%.
I would just monitor those voltages, before and after every flight to make sure that one of the cells didn't start to drop significantly from the others.

Thank you for the reply. Really appreciate it.

EyeInStein · Oct 9, 2015

I just don't get that lowered battery life. I'm looking at 100% battery life on 3 batteries that have been charged the same number of times and more.

Enjoy your vids fhagan. Not wanting to hijack this thread but did DJI determine your crash was covered ?

fhagan02 · Oct 9, 2015

EyeInStein said:
I just don't get that lowered battery life. I'm looking at 100% battery life on 3 batteries that have been charged the same number of times and more.

Enjoy your vids fhagan. Not wanting to hijack this thread but did DJI determine your crash was covered ?

Thanks for the comments. DJI covered the crash and fixed it free of charge. They never responded to multiple emails asking what caused the crash... but they fixed it after two back to back RMA's. Five weeks total.