Got a new battery today from the sale on the DJI Online Store. Charged it and upgraded the battery firmware. One cell is .06 volts lower than the others. Let the drone idle until the app reported 75% remaining. The same cell still has a .06 volt deviation. Turned on the battery this time and fully charged it again. Same deviation. I don't think it's a good idea to deep cycle it this early in the game. Any suggestions before I return it?

I find it quite normal that one cell may be a little lower than the others.
Fly your battery to 50% the first ten flights, then deep cycle it.

RedHotPoker

Here we go again with the deep cycle rubbish .....

Deep cycle does nothing. Even DJI no longer advise it in their Battery guidelines.

To OP - contact DJI .... try to get a replacement battery. They may advise deep cycling, old crap habits die hard ! Do what they say - when it doesn't work - push for replacement.

Why does it happen ? The DJI board on the battery is a charge controller. It detects max charge voltage and terminates before all cells are actually balanced. Repeat charge does nothing as the board just terminates without allowing balancing CV charge.
In deep cycle - the board detects total voltage 12v , not individual 3v cells.
Balancing requires monitoring of individual cells - not total voltages.

Nigel

Until DJI officially announces not to deep cycle our intelligent flight battery packs, I will continue to do so.
Not for you to call rubbish. Do what you will to yours ok? Ah, but allow us to have our peace, please.
You are in someone else's battery thread now.
Perhaps starting your own forum would allow you all the freedom....  Haha


RedHotPoker

I will always put information to help others avoid damaging items.

In fact DJI has altered its guidelines for battery maintenance ... but I assume you ignore the old vs later battery Guideline documents ?

The old did advise to Deep Cycle ... the latest has removed that advice. Unfortunately whoever wrote the owners manual has failed to do same ... so we have this ridiculous repeat of crap advice to deep cycle.

I have on many occasions explained why it is bad advice ... there are others with experience of LiPo's who have stated similar.

So RHP ... you can do as you wish - but refrain from telling me to stop helping others .....

Just to make it clear : No LiPo manufacturer or experts online advise to Deep Cycle LiPo's .. FACT.

DJI are not manufacturers of LiPo's - they are buyers of assembled packs. DJI chose in the PAST to give bad advice which has subsequently been removed from the Battery Guidelines.

Sadly - not everyone seems to have got the message ....

Nigel

Betamace ...

It is your choice and I am not going to shout at you to follow my information.

What I will suggest is as I said before - discuss with DJI - do as they say - when it still fails to sort the issue - get them to replace.

Technical note :
A LiPo cell that shows low voltage compared to companion cells if fully charged and still maintains such difference will never recover. You may individually charge that cell to same IF you can get to the individual cells contacts. But as soon as a load comes on that pack - that cell will suffer a greater voltage drop negating any extra work to bring it up to full voltage charge. This is well known to millions of LiPo users worldwide and also well documented by LiPo manufacturers.
With controlled discharge monitoring each cell to avoid over discharge. You can bring each cell to identical voltage level. But the differing internal Resistance of the cells will mean when charging - the cells will return to their unbalanced state and not maintain balance. This is also well known to millions of LiPo users and well documented by LiPo manufacturers.

Nigel

solentlife Posted at 2017-1-24 00:59
Betamace ...

It is your choice and I am not going to shout at you to follow my information.

As a newcomer, I  find it hard to believe that 1/100th of a volt can really matter........ I'm obviously wrong here though.  Perhaps it just gets worse?

GeoffN Posted at 2017-1-24 01:49
As a newcomer, I  find it hard to believe that 1/100th of a volt can really matter........ I'm obviously wrong here though.  Perhaps it just gets worse?

The OP has a cell of 0.06V less than others.

The DJI battery is a HV LiPo and designed to 4.35V each cell.

That means he has one cell of 4.29V and all others 4.35V .....

I agree that the battery will fly the model - the only factor will be the slightly less flight time if trying a long flight.

0.06V is about the max difference you would want AFTER charging as a reasonable battery. The fact is - this is a new battery and should not be at that stage. 0,01 or maybe 0.02V - I accept ... but 0.06V is not good. It would only take a slight increase in Internal Resistance - especially if deep discharging is done - to increase that difference such that battery becomes a short flight jobbie.

For me 0.06V as a relatively new pack is over the acceptable border. If it was 6 months use down the road - that's different.

Nigel

Yep. It can only get worse. I opened a ticket a few minutes ago.

Fingers crossed - hope it all works out.

Nigel

solentlife Posted at 2017-1-24 10:22
Fingers crossed - hope it all works out.

Nigel

Thx. I waited 20 days for that battery and will probably have to wait another 20 for DJI to honor their warranty with the shipping factored in.

I wonder if they messed something up with the 1.7.9 firmware update. On a flight on October 30th with the previous firmware version (1.6.8 I think?) I flew and saw nothing unusual with the battery, here's the HealthyDrones battery page from that flight: http://healthydrones.com/main?sh ... =POWERBattery_Cells

On November 10th I flew after updating to 1.7.9 and HealthyDrones showed the battery was significantly unbalanced, with cell 1 quite a bit below the others: http://healthydrones.com/main?sh ... =POWERBattery_Cells

If you can find another P3 owner - stick the battery in and see what it says then.

I would be surprised if the FW makes any difference unless the update to the battery board was faulty ?

Unfortunately unless you open the case - there's no way like other lipo's to check individual cells manually.

Nigel

solentlife Posted at 2017-1-24 21:59
If you can find another P3 owner - stick the battery in and see what it says then.

I would be surprised if the FW makes any difference unless the update to the battery board was faulty ?

Open the case HA HA!

Actually done carefully - it is not a risk as some think ...





etc.

Nigel