How bad is it really to store battery at 100%?

[royster]

This may be a stupid question- Can i assume the rules of storing or leaving batteries as discussed above also apply to the RC? For instance, my P3A- RC i just leave without really looking at bat. level, but lets assume i will leave it at 60-70%, for a couple of weeks, as my Mavic sees most of the flying lately.
Should i make sure the P3A's RC is at 40-50% if not flying her for a few weeks?

 

[Mark The Droner]

There are no DJI guidelines for RC storage. Most experienced pilots ignore the RC and all is well. A few weeks isn't going to matter anyway. If you were going away for a year or something, you might think not to leave it fully charged, or you might deliberately want to leave it around half charged, but otherwise, most people don't worry about it.

 

[With The Birds]

The reason we need to fuss over our flight packs is because they are subject to much higher demand in use. The fact the pack will be flown to depletion in around 1/3 of an hour tells us the average discharge rate is 3C. The controller battery will give you a couple of hours use, that’s 0.5C average, 1/6 of the current demand of the AC. The higher the current draw placed on a battery the more chance it will fail in use. It’s like an engine with worn big end bearings or low oil pressure. It might get you around town for years but could fail catastrophically with 10 seconds at WOT.

 

[solentlife]

40% is a good practical SOC to allow for some self discharge in storage. Lower is better. If I have a pack at 20% after a flight and I expect to use it in a week or so I don’t bother charging it. I suspect DJI”s guidlines are more aimed at ensuring battery reliability for the less attentive user, as a safety margin.

Your observation is correct, the fuel gauging algorithm in the battery works on available charge accounting for actual load conditions, temp, internal resistance and other factors. The percentage will not increase after a flight. What @solentlife is taking about is voltage, voltage will increase after the load is removed from the battery and it is this resting voltage that is most relavent to storage.

If a cell drips below 2V for a week it will be permanently damaged. Quality cells are fine above 2.5V. DJI packs report 0% at 3V.

Thank you ...

It is a well known fact that a battery that comes of use will 'bounce back' a small amount. The 30% back to 35% is an average I observe usually and the % is based on the 'Fuel Gauge Table' and as WtB says - on the voltage measured.
Given the extensive discussions and information available in near all forums that include LiPo use ... the manufacturers online sites ... even the 'out of date - needs updating' Battery University pages will confirm this.

LiPo usage is now so widespread - that users experiences allied to manufacturers info has built up a wealth of info. But at end of day - the most important aspects of LiPo use are :

Do not overcharge
Do not over discharge
Do not store higher than 3.9V per cell
Do not store lower than 3.7V per cell
In use - keep within specification discharge rates

Nigel

 

[solentlife]

"Quality cells are fine above 2.5V. DJI packs report 0% at 3V."

Most battery techs will advise you to NOT push a LiPo below 2.85V at which irreparable damage can occur. The chemistry is not designed to be subjected to such low value.
3.0V is advised by most to be the lowest figure you should push a LiPo cell to UNDER SIGNIFICANT LOAD .... 3.3V without significant load.

Unfortunately today general RC ESC's still have user options to allow LVC at too low a figure ... a hang-over of early days.

DJI zero figure has been set at 3.0V for some time now but only achievable when non-flight discharge.... such as leaving AC powered up or using a 3rd party discharger. Personally I advise strongly against discharging to that level.

My opinion on use and care is not only based on my own observations and tests, but also on the advise of a Senior Tech who worked for Mallory - world leading battery manufacturers and systems company.

I know there are others who will disagree or differ on some points. The world is a big place and its up to each to find their 'comfort' zone.

Nigel

 

[DronerDave]

Thanks for that response, maybe rotating batteries is a better idea than keeping the same one charged. And also, with all due respect, there is a sunset every night but the ones that are worth capturing with video are infrequent and unpredictable. ;-)

I get it but it aint film . and you have to discharge anyway . Go fly . If it isn't a perfect video delete it . Sometimes the ones that look crappy from the ground are sweet at 300 feet .

 

[Seevee]

Regarding auto discharge....
The manual says it auto discharges to 65% if idle after 10 days. If so, it won't take long to recharge back to 100%.

And is there any reason one would want to discharge it sooner, or less that 65%?

 

[solentlife]

Regarding auto discharge....
The manual says it auto discharges to 65% if idle after 10 days. If so, it won't take long to recharge back to 100%.

And is there any reason one would want to discharge it sooner, or less that 65%?

That is selective editing of what is DJI statement.

Default factory setting is 10 days idle. But it has User option to change to any figure from 1 to 10 days. The figure it discharges to cannot be changed.

BUT discharge does not stop at 60 - 65% ... in fact it will continue at a slow rate till it reaches Hibernation Level .. which will then be stop. This could take many months or years ...

Hibernation level is not something you would want intentionally.

Nigel

 

[jephoto]

Consensus on many posts & articles I've read say 40-50% for long term non use seems to keep the battery healthy. At at least not harm them.
During the winter here in Chicago I don't fly much from late November to April or May.
So I bring them down to 40-50% and check them every couple of months.

 

[N017RW]

Anyone who has purchased LiPo cells or packs would attest that they are at an ~50% SOC at the time.
This should be an indicator of proper storage technique.

 

[Ged2217]

Not sure if this is related but I had a perfectly good battery that was discharged for almost a year, when I got it back out and charged recently it charged as it should, however I left it fully charged in the bag for a month or so and now wont turn on or charge. I've tried leaving it on charge for hours etc and still nothing, no lights or anything.. it's dead

 

[N017RW]

One has to differentiate a fully charged battery with one that has nominal Capacity.

The latter is more critical.

It is common to confuse a fully charged battery which is based on voltage to that of one that is able to store a charge.

 

[solentlife]

Not sure if this is related but I had a perfectly good battery that was discharged for almost a year, when I got it back out and charged recently it charged as it should, however I left it fully charged in the bag for a month or so and now wont turn on or charge. I've tried leaving it on charge for hours etc and still nothing, no lights or anything.. it's dead

OK but without some idea of numbers, no-one can really suggest or comment ...

Discharged for a year ? What was level of battery when stored ? Storage charge at 30 - 50% ? Or fully discharged near 0% ?

When you charged - was it with DJI charger which only indication you have with it is when LED's stop ! That's the real downside of the DJI Powerbrick charger deal ... you know zip about what's happening in the charge.
Did the charger continue on for expected charge time before cutting out ?

When you tried to charge - did you follow the Hibernation mode instructions ? To be honest if you left it for a month at full charge ......... Hibernation mode is unlikely.

What is more likely is that your extended discharged time is the culprit. Trouble is - even if you manage to revive the battery - will you trust it ?

Nigel

 

[quaddamage]

Dji on RC battery:

 

[solentlife]

RC Battery .... yes its generally assumed that any question about battery is Flight Battery - often ignorng the RC one.

As the video shows - this is a LiPo battery also ... in the Standard it is a 1S battery of 3.8V nominal (4.2V full) ... Advanced and Professional are 2S battery of 7.4V nominal (8.4V full) ... and are subject to same storage / charge problems as any other LiPo.

The interesting point though is that DJI chose not to install auto self discharge to the RC battery circuit - I assume to be safe in removing possibility of trying to use in discharged state ?

Nigel