Leaving battery charged.

[Dpnuggs]

Hi all. New here. Just got a P3S and really digging it. So I don't plan on flying again until Wednesday. So do I charge battery now (it's currently at 30%) or just leave it where it's at and charge it Wednesday right before I fly. Or does it not matter what I do with the battery as long as I'm using it on a regular basis. I do plan on flying every weekend. Just want to get every last drop out these expensive batteries.

 

[macmac360]

you can probably do it either way, I fly about twice a week and usually charge it the night before I plan on using it but I don't think it really matters

 

[Dpnuggs]

I guess my main concern is leaving at 30%. I know it safely discharges to 50% or so automatically after 10 days. So wasn't sure if it sits for a week or possibly more at 30% if that would harm it.

 

[msinger]

It's best to keep the battery at the storage level when not in use. If you'd like to do that, charge it until the 3rd battery light starts blinking. Then, fully charge it before you fly next time.

 

[Dpnuggs]

That's what I was thinking. Thanks for the advice. Go Falcons!!

 

[WilliamM]

That's what I was thinking. Thanks for the advice. Go Falcons!!

OT is a *****, sorry for your loss. But back to batteries, 30% is just fine for a few days, I do it all the time. Then give them a full charge the night before or morning of the next flight. Now if your talking long term storage like a week or more, the something closer to 50% is best. Now on this 10 day delay before auto discharge. That may be the default, but that's too long for a batter to be seating at 100% and not be used. A setting for something between 3 to 5 days is much better. That's you backup in case you forget that your charged them, and something happen to your plans and you didn't go flying.

 

[solentlife]

30% is fine to do long or short term storage. No need to go up to 50% as in fact over time the auto discharge will bring her down below 50% anyway.

Nigel

 

[msinger]

No need to go up to 50% as in fact over time the auto discharge will bring her down below 50% anyway.

The auto discharge will only bring her down to 65%.

 

[solentlife]

The auto discharge will only bring her down to 65%.

Not according to DJI themselves ... initial discharge point is BELOW 65% - continued non-use takes battery down further and will drop well below 50%.... in fact they even advise discharge between 40 - 65% manually. Page 3 Guidelines.

For most experienced users of LiPo's - 65% level is too high as its at the maximum storage voltage ... most users would look at the 35 - 50% mark as better for battery and cell life. A voltage per cell of 3.75 - 3.85V

First thing ... the DJI LiPO is a HV version of 4.35V at full charge BUT despite some peoples thinking - it does not alter the table above after the use of first 10 to 15% of power. Only in the first 10% or so do you get any real benefit of the HV version. After that the LiPo acts same as a regular LiPo.

The DJI battery is a 4S pack ... that is 4 cell. So for each individual cell IF you could measure it would read according to the 1S column above. Total values as per the 4S column of course except for that initial 10%.

Nigel

 

[msinger]

Not according to DJI themselves ... initial discharge point is BELOW 65%

I'm not sure where your information is coming from, but the Battery Safety Guidelines contains the best information on this topic. Here's what it states:

continued non-use takes battery down further and will drop well below 50%

That will surely occur over an extended period of storage time. My comment above was in reference to your claim that the "auto discharge will bring her down below 50%". I was simply clarifying since the auto discharge process does not discharge the batteries below 65%. After the auto discharge process has completed, you can safely store the batteries untouched for at least 2 months.

in fact they even advise discharge between 40 - 65% manually

I doubt most people are manually discharging batteries. That's a lot of work and is probably unnecessary since there aren't a bunch of complaints of dead batteries due to not following that recommendation.

 

[RJersek]

How do the batteries auto discharge, I've seen the option in the go app for the discharge time but wondering how it actually works if you need some sort of load on the battery


Sent from my iPhone using PhantomPilots

 

[solentlife]

msinger ... you contradict yourself ... excuse me for pointing it out ... you even ring in red the passage that says BELOW 65% ...

Discharging manually is easy in fact. Either by flying ... or by one of the energy transfer dischargers sold online ... you can either power a lamp or even charge a mobile / tablet etc. from it.

The matter of discharge below 65% and below 50% was actually posted by DJI themselves - unfortunately I didn't save the link but will do my best to re-find it.

The statement I made was : "over time the auto discharge will bring her down below 50% anyway." ... the emphaisis is on the words OVER TIME ... which I hoped people would understand as extended.

Therefore let me write in the full manner ... Over extended time the self discharge of the DJI battery will take it well below the 65% mark and in fact below 50%. This takes significant time due to the method of energy dissipation used. The depletion rate is significantly slow as there is no energy transfer or such setup other than resistive load.

Nigel

 

[120CCPM]

OT is a *****, sorry for your loss. But back to batteries, 30% is just fine for a few days, I do it all the time. Then give them a full charge the night before or morning of the next flight. Now if your talking long term storage like a week or more, the something closer to 50% is best. Now on this 10 day delay before auto discharge. That may be the default, but that's too long for a batter to be seating at 100% and not be used. A setting for something between 3 to 5 days is much better. That's you backup in case you forget that your charged them, and something happen to your plans and you didn't go flying.

Totally agree, there's no need to worry too much about 30 vs 50%, unless you're really talking about long-term storage. A resting voltage in the 3.70-3.85 V/cell range is totally acceptable.
What's really important is to understand that when a LiPo is fully charged, is in a "stressed" state that - over time - will affect its ability to store/release a charge. Hence, keep this to a minimum (and set self-storage to 3 days, as William suggested).

 

[msinger]

msinger ... you contradict yourself ... excuse me for pointing it out ... you even ring in red the passage that says BELOW 65%

I'm not contradicting myself really. I think you're just a tad bit pedantic.

The documentation states it takes a few days to discharge the battery to 65%. It doesn't matter much whether it's really 65% or 64.9%.

 

[120CCPM]

How do the batteries auto discharge, I've seen the option in the go app for the discharge time but wondering how it actually works if you need some sort of load on the battery

The self-discharge time is set in the DJI GO app and saved in the battery itself. The internal circuitry of the battery (what makes them "intelligent") will wait for the specified amount of time, then activate an internal resistive load which will discharge the battery to whatever level DJI has deemed to be good. In the process, the battery is expected to become slightly warm. There is no need for an external load.

 

[RJersek]

Interesting, thanks for the info


Sent from my iPhone using PhantomPilots

 

[solentlife]

Hi msinger .... sorry if you think I'm being 'pedantic' ..... but we have a lot of new people join the RC world with these models and have no knowledge about storage / care of LiPo's. Sadly DJI info is not the best and is at odds with many other expert LiPo users.

I have posted a lot about storage levels, effects on iR, Voltage drop, performance etc. to try and help such people and some of the older longer term owners who still don't grasp the concept.

We have a guy here who is worried about his LiPo being at 30% .... which anyone with reasonable knowledge of LiPo's knows is a safe storage level. But statements about the 65% that you mention can lead such people to 'panic' and charge up their LiPo's unnecessarily. I'm not hitting at you - I'm actually not amused by DJI actually with this.

The article I want to find was DJI talking about Auto Discharge and then continued slow discharge until hibernation - which they said had battery at below 50% when hibernation occurs.

I think I can safely say that not only myself - but many others who have used LiPo's for many years would never want hibernation to occur at 65% !! Given that 65% is actually at maximum or slightly over recognised good storage level.

I wish OP to have good information so his batterys last maximum time and give him maximum benefit.

Nigel

 

[120CCPM]

I think you guys (Msinger and Nigel) are more in agreement than you think. There are people reporting that DJI batteries do effectively discharge beyond 65%, but this seems to happen in 3 separate phases:
- first phase is a fast, "active" discharge, via internal resistor (battery gets warm), that starts after the number of days set in DJI GO and brings the charge down to 65% in about 2 days
- second phase is a slow discharge, not sure if obtained intentionally via internal resistor at lower current or simply because of the current pulled by the "intelligent" circuitry, until about 50%
- third phase is hibernation, with zero (or near-zero) current drain, to prevent over-discharge in case of long-term storage
Whether this is true, I don't know... but it definitely makes sense, and actually explains some of the wording in the battery manual.

 

[DanMan32]

Slow discharge due to intelligent circuits makes sense.

Sent from my HTC 10 using PhantomPilots mobile app

 

[solentlife]

I think you guys (Msinger and Nigel) are more in agreement than you think. There are people reporting that DJI batteries do effectively discharge beyond 65%, but this seems to happen in 3 separate phases:
- first phase is a fast, "active" discharge, via internal resistor (battery gets warm), that starts after the number of days set in DJI GO and brings the charge down to 65% in about 2 days
- second phase is a slow discharge, not sure if obtained intentionally via internal resistor at lower current or simply because of the current pulled by the "intelligent" circuitry, until about 50%
- third phase is hibernation, with zero (or near-zero) current drain, to prevent over-discharge in case of long-term storage
Whether this is true, I don't know... but it definitely makes sense, and actually explains some of the wording in the battery manual.

That is exactly what has been found by myself and others who have been looking into the battery matters,

Thanks

Nigel