Just had my first battery problem. I had around 7 min of fly time left yesterday and the battery went all the way down to 7% like a rock. Luckily, I saw that it was dropping and landed it. I got back home and the Phantom Assistant Software. I'm afraid to fly it now with this problem. I have another battery that I had fully charged and drained it down to test and got a cell damage warning today. The batteries have always been stored in a tradecraft case, always room temperature.  I have not flown it since late January and it's stayed in the case.  I bought it at US Hobby back in May.  Any suggestions?

What battery percentage did you store them at?

After reading all these battery stories, i now keep track of everything. Like writing down celvoltages, totals and % charged etc. In your picture the cell voltages (around 3,7v) look good, but should be around 27% charged, not 7%.
The battery who has 1 cell around 3 volts, maybe dead.
Did jou fully discharge your battery after 20 times of charge? This seems to be very important to these batterys! If not, try this now (if its still possible). Discharge until the battery wont go on, and then have a full charge, en see if it will work again.

I had them fully charged when I stored them in January.  The first battery I just charged it when it was at the 7%.  I'm going to test it here later.  I'm currently charging the one with the dead cell indication right now.  I'll replug it into the vision assistant to see if it still comes up dead cell again.  

bpope2385 Posted at 2015-3-11 01:42
I had them fully charged when I stored them in January.  The first battery I just charged it when it ...

Hopefully, it'll recover, good luck!

However, storing Li-Po's fully charged is a big no-no I'm afraid. I suspect you may have killed it.

They should always be stored at roughly 50%. I don't think it's as super critical as some (paranoid? ;)) folk like to believe, anywhere from 30-70 is probably OK, but 3 months full is not good.......

Having said that, aren't the 'new' batteries supposed to 'self discharge' after 10 days? Anyone know the deal there?

Cheers,
Ian

Have you done the recommended battery discharge per the information displayed at the bottom of the picture you posted. Well I notice you do not have go home low battery level indicator selected. You may had otherwise received a warning

bpope2385 Posted at 2015-3-11 01:42
I had them fully charged when I stored them in January.  The first battery I just charged it when it ...

Just to clarify something,  you said you stored them fully charged in January but did you recharge them prior to using them after storage or did you fly with them straight from storage without charging?

I've had the batteries down to 6% before and then charged them back up.  Not  problem.  Maybe since I've had them stored for month fully charged like you said that's the problem.  Definitely a learning lesson if they do recover. I'm going to test it later and see if it does it again.

Yes, from what I've read, the newer batteries are suppose to "self discharge" after 10 days of non use.  

Thanks for the replies!

And make sure you enable low battery level "go home"

bpope2385 Posted at 2015-3-11 02:22
I've had the batteries down to 6% before and then charged them back up.  Not  problem.  Maybe since  ...

Storing them at full charge does have a negative effect on the longevity of the battery however it is a slow deterioration process and not something that causes sudden failure with one month storage.  One thing that can happen during storage is that cells become out of balance, meaning that the voltage between the 3 serial pack pairs may differ greatly from each other and that can become a problem if the battery is getting discharged under load without prior charging and balancing the cells because the cell pair with lowest voltage can drop into damaging low voltage levels  (<3.2-3.4V under load) before the internal LVD, which looks at voltage across all 3 cell pairs, kicks in.

That's what I was thinking, I didn't think with a months storage it would damage them.  I'll report back after a test this evening hopefully.   The other battery with the cell damage is now fully charged so I'm going to take them out to the field, put lift them just above ground and see what happens.  

bpope2385 Posted at 2015-3-11 03:29
That's what I was thinking, I didn't think with a months storage it would damage them.  I'll report  ...

Yeah try it but just discharge it something like 50% even if it works good and after dbl check with the assistant if the voltages between the cells are still almost balanced

So it looks like I'm SOL.  Took it out today and put in the air to about 30ft with the first battery that died yesterday and went to 7%.  The app said I had 5 min of fly time (40% batter I want to say) time left and dropped down to 7% and auto landed.  So it looks like that battery is bad.  

I popped the second battery in that came up with a bad cell warning.  Put it in the air at 30ft and just watched.  Basic movement.  It did great until it got down to 33% and it dropped like a rock as well.  It auto landed but almost didn't make it as it got to 5% when it landed.  

Guess I'll have to buy new batteries which sticks.  Any other advice?

I've stored batteries for a couple of months or more fully charged and have had no problems. I believe the new V2.0 batteries automatically discharge after a week or two, but my V1.0 battery sat unused and fully charged for about 3 months fully charged and works just fine.

Even though they were stored for month fully charged, shouldn't these batteries not fail like this?  I mean this could have been dangerous if I were flying far away, there would have been no time to bring it home and land.  From what I've read, these things should have a life cycle of 400  cycles before the cells go bad.  I've tried to email UShobby but they did not email me back about issue.  

The earlier batteries did not have an auto discharge as far as i know and if you did not know to store them with ie. 50% charge i think you are SOL sorry to say and yes it sucks, these freaking batteries are stupid expensive. As for dangerous, yes, some folks have reported swelling and worse...I would see if you have any luck with UShobby or you could always try DJI..Good luck.