BATTERIES @FULL CHARGE VOLTAGE

[360 Guy]

THIS IS JUST FYI ONLY, hope the information within is helpful to another.
Because of minor swelling, I've replaced two (2) batteries in my three (3) battery lineup.
With nothing to do on a cold rainy day, I tested my three batteries for voltage.
I have each battery numbered on its case as I try to use so they all have the same number of usages.

Battery testing is with the battery(s) inserted in the MINI 2, powered up, along with the controller.
Tap "control" and read the battery condition on the screen.
Number 1 battery reads 4.24 volts with one charge (new battery)
"Recharging" this battery, @full charge it now reads 4.35 volts. (FULL)
Testing #2 battery after sitting about 4 days......4.28 volts with 20 charges.
Testing # 3 battery after sitting about 4 days reads .......4.29 volts with 6 charges
Number 2 & 3 batteries were replaced with new and these are the readings of those replacements.

In conclusion, each day sitting, the battery will lose approximately .0875.

Again, it's just FYI

 

[DoomMeister]

I’m seeing it discharging 0.0175V/day.

4.35V-4.28V=0.07V, 0.07V/4days=0.0175/day

 

[Bad Santa]

Voltage drop is just one number. The # of mA is what really matters

 

[Cafguy]

In conclusion, each day sitting, the battery will lose approximately .875 volts per my calculations.

Not good for a LIPO.

 

[360 Guy]

Cafguy............explain please, as I'm not an electrician.​

360

 

[DoomMeister]

@360 Guy

What @Cafguy meant was that if your calculations were correct your batteries discharging 0.875V/day would be excessive and a problem with the BMS (battery maintenance system) or faulty cells was the cause of that.

From the data you supplied in your original post I calculated that batteries 2 and 3 were losing only 0.0175V/cell/day.

 

[slup]

...Battery testing

Aren't you forgetting about below...

 

[DoomMeister]

Aren't you forgetting about below...

View attachment 181017

I didn’t forget about it @slup, but his figures were way off at 0.875V/day. I also wonder what V/cell these batteries go to for storage level.

I now see that he edited his original post to read 0.0875V/day, but that still seems excessive as after 9 days the cells would be at 3.56V/cell. These cells must be LiHV to be at 4.35V @ 100% therefore storage voltage would normally be at 3.85V.

Any light you can shed on this would be appreciated. You are one of our gurus!

 

[slup]

I didn’t forget about it...

It was directed to the OP... the quote is from the OP's first post.

Otherwise I can't figure out how he came to 0,0875V/day... it's to many unknowns in this, full & after 4 days measurements on different batteries, was the full measurement done after the battery had given the possibility to rest, add to this the auto discharge after one day... & on all this, the measurement was done with a discharging battery (it's powering the drone during measurement).

The measurement should preferably be done after the battery have rested approx a day after a full charge (but here the auto discharge screw thing's up unfortunately)... the measurement should also be done directly on the battery terminals.

The only reliable method to measure these "Smart" batteries regarding self discharge is a voltage check on the terminals after that the 9 day auto discharge have finished & then measure the same battery on the terminals after a set time (a month maybe).

 

[Calson]

Batteries are designed to provide a high voltage for as long as possible. Measuring the voltage tells you next to nothing. For my rechargeable AA lithium and NiMh batteries I need to use a ZTS pulse load tester to determine the state of batteries. The batteries after charging will show 1.5 or 1.4 volts but may only hold 60% of the charge they would when new. They recharge faster over time as less charge is being stored in the battery.