Scary after critical battery, got questions!

[RoboticTundra]

Lithium ion batteries don't suffer from any type of memory so using them from full charge is not only non-damaging, it's recommended. Reason being, they have a life expectancy based on cycles (charge/discharge). If you were to only use 50% of the battery charge, it would amount to one cycle, the same as using 70% or 80%.

Edit: However, there may be some merit to a partial discharge in that it does not stress the battery as much so its life may be extended. However, I don't think this applies to flying a drone. You want to be at the max capacity when starting out as the flight time algorithm would be more accurate.

DJI batteries contain electronics that won't allow the battery to discharge to 0%.

Recommending a 95% charge is simply bad advice.

Jeff Dahn, Elon Musk, and every battery engineer I have ever discussed this with disagrees with you.

Here's a consumer friendly discussion on it: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

 

[tcope]

Here's a consumer friendly discussion on it: How to Prolong Lithium-based Batteries - Battery University

That is the article I read that has me back peddling a bit. However, there are other things to consider. Which is more important in for drone usage, getting more cycles or giving up a few in order for the drone to stay in the sky and return home? Charging to "95%" is just a guess by the software. It might be at 95%.... it might be at 80%. This is also going to throw off the algorithm that the software uses to determine flight time.

So I'd tend to agree with your statement on how Lipo's act, just not with it's use for a drone battery.

 

[Mossiback]

It is possible that DJI took into account the proper way/amount to charge/discharge their batteries when they built the batteries, chargers, and firmware so we mere users do not need to worry about it.

 

[RoboticTundra]

So I'd tend to agree with your statement on how Lipo's act, just not with it's use for a drone battery.

So, I consistently charge to 95% and you to 100%. After some number of flights I've lost 1% of capacity but you've lost 6%. Now we're even. But not quite. I still get about the same flight time as I always have from a 95% charge but you are now getting the same flight time as me and less flight time than you were and for 100% of charge. Your capacity and flight time will continue to degrade faster than mine so at some point I'll be getting 22 mins but you'll only be getting 15 mins. Better to get 22 mins for hundreds of flights for 24 mins for a few dozen and then declining flight time?

Use case matters quite a bit as well. If I'm using my MPP to do five 10-minute flights each day around construction sites then I have a couple of options. 1) I can have 2 or 3 batteries and continuously do a full charge and near full depletion which will give me a fairly short battery life. Or 2) I can buy 5 batteries and always charge them to 80% and use each for one 10-minute flight each day and get very long battery life. Chances are I will come out money ahead with the 5 battery plan.

It is possible that DJI took into account the proper way/amount to charge/discharge their batteries when they built the batteries, chargers, and firmware so we mere users do not need to worry about it.

Possibly. But we don't know? I assume they have at least a 5% buffer at the bottom. Ideally they have a 15% buffer at the bottom and 10% at the top but we don't know that. Given the power to weight problem I'd guess that they likely have 5% at the bottom and maybe 1% or 0% at the top in which case charging to 80% or 90% or 95% whenever you know that you'll be doing a shorter flight will prolong your battery life a fair bit.

One big question is what have heavy users seen with battery life over longer periods.

 

[Mossiback]

...One big question is what have heavy users seen with battery life over longer periods.

I charge my batteries to 100%, or as much as the DJI charger puts in to turn off the indicator lights. I then fly until Go 4 tells me I need to return home (I get to around the home point before being told) and then land before being forced to. When I get home I recharge everything on the DJI charger. I then pack it all up and fly the next day. I have been doing this almost daily as weather allows (Seattle) for over a year on the original batteries and have not noticed my flight times reducing.

 

[RoboticTundra]

I have been doing this almost daily as weather allows (Seattle) for over a year on the original batteries and have not noticed my flight times reducing.

But 4 flights does not make a good statistic

 

[Mossiback]

But 4 flights does not make a good statistic

4 flights? I must be missing something, and I do not want to re-read this entire thread, but I was saying that almost daily I have been charging completely and getting all the flight time I can from my original batteries for over a year without noticing any reduced flight time.

 

[RoboticTundra]

4 flights? I must be missing something

"as weather allows (Seattle)"

And note the smiley.

I almost moved to Seattle to work for Microsquish. While having dinner with some colleagues and spouses one told my wife that the weather wasn't really that bad and that she'd get use to it. That ended the discussion.

 

[Mossiback]

"as weather allows (Seattle)"

It has been drier than normal out here.

EDIT: Removed snarky attitude.

 

[tcope]

So, I consistently charge to 95% and you to 100%. After some number of flights I've lost 1% of capacity but you've lost 6%. Now we're even. But not quite. I still get about the same flight time as I always have from a 95% charge but you are now getting the same flight time as me and less flight time than you were and for 100% of charge.

If we are using "about"... then I'm getting "about" the same flight time even after all of those charges.

How is it that you know you are charging a battery to 95%? Only knowing what the lowest cell is reporting can anyone have any idea what the charge really is. So you could actually be at 80% or 85% or 99%. Let's just ignore that for a moment. You say at 95% you are getting "about" the same flight time. No. I'd be getting 24 minutes and you'd be getting 22 minutes. What you'd gain over hundreds of cycles is around 10%. But again, over hundreds of cycles you'd be getting less flight time. Most people are going to be rotating 3 batteries. So it would take around 600 fights to get to that 10% break even point. That could take YEARS! Again, in the meantime we _know_ you are getting less flight time from each battery. This also ignores that I don't think anyone can really know when their battery is 95% while it is charging.

So, guessing at the percentage of battery instead of 100% and getting less flight time for years. I think I'll still recommend 100% charge.

 

[Mossiback]

But 4 flights does not make a good statistic

OK, you got me.

 

[kidroc]

I don't care what that service says i will NEVER do the 8% thing it's bad advice from every source.I do the 30% as a rule and now have three batts with over 120 cycles and there getting old but the cells are in great condition..

 

[Robbyg]

I don't care what that service says i will NEVER do the 8% thing it's bad advice from every source.I do the 30% as a rule and now have three batts with over 120 cycles and there getting old but the cells are in great condition..

Yep anything less than 30 at touch down is going into the risky area. S-Happens and believe me I know first hand.
BTW that video shows a rookie mistake. If there is any doubt about battery life on the return and you have an option to fly over land and not over the water, then go over land even if the water is the most direct path.

Rob

 

[Lincos]

Hi technicians,


I have read all of the treads about battery's. Just because i don't understand it.

Now… after a lot of reading i still don't understand this matter. And… i think I’m not the only one. Beside that it’s very difficult who to believe who is right or wrong about this chemical process.


Now i made a simple mindset.

We all invest about a 1000 bucks or more for a flying camera. Who cares the f***ing battery!?

Just load them up and fly the **** thing and make sure you get it back before the crash.

If the battery losing power you order a new one. Some people have to buy after 18 months and other at 3 years.


If it is a big money issue stick with your point-and-shoot camera (don’t forget to read the battery maintenance manual)


Happy flying to all of you!

 

[Lapeer20m]

In my own testing, and in expirements performed by others in this forum, sport mode always provides the most miles per battery compared to p mode with obstacle avoidance turned on.

I don’t know if it is more advantageous to use sport mode when battery voltage is very low as someone indicated earlier in this thread due to the increased amps.

I get about 30k feet total distance per battery in p mode and about 36k feet in sport mode if I fly in a large circle over a field near a place I fly often.

I’ve flown hours and hours with 7 different batteries and two different mavic in all sorts of wind conditions and temperatures and every time I get the most flight “miles” out of sport mode.

 

[Soonerdrone]

Where in the manual does it say you need to discharge the battery to 8% every 20 charges? If this is something you personally do because you want to, that's fine, but I wouldn't be giving false information based on personal preferences.
Li Po batteries have come a long way and doing these complete discharge/recharge cycles aren't as necessary as they used to be.

In the manual it says to fully charge and discharge the battery once every 3 months to maintain battery health .At what level of discharge it doesn't say...It just says fully..up to interpretation I guess

 

[hookalakupua]

Here's my personal experience and history. Not right or wrong as it's just what I do. Offering it for others to debate and in order for informed decisions to be made.
1 - 4 Batteries that I rotate through after each flight.
2 - Each battery is fully charged after each flight.
3 - In general, I land with between 8%-12% battery left and have never had an issue in doing so. I have the sound removed so the Warnings aren't a bother. I've landed under 5% on probably 20 different occasions and have never had an issue either.
4 - The 4 batteries have been cycled 42-47 times each.
5 - On 6 occasions, I've had Critical Battery alerts due to low voltage issues in flight. I've returned home, recharged and proceeded as normal.
6 - The bags are stored in lithium ion bags and well looked out after.
7 - The MP is flown to the extreme as most parameters have been changed accordingly.
8 - Batteries are 15 months old and still going strong.

If anyone wants further information, just let me know as glad to share.

Happy Flying!

 

[Mossiback]

... sport mode always provides the most miles per battery compared to p mode with obstacle avoidance turned on...

There is a third option, and that is p mode with forward sensors off. The speed is between p and sport mode and the sticks are not as sensitive as in sport mode. I have read (but not tested) that it will also give the best battery performance.

 

[ados_cz]

Hi technicians,


I have read all of the treads about battery's. Just because i don't understand it.

Now… after a lot of reading i still don't understand this matter. And… i think I’m not the only one. Beside that it’s very difficult who to believe who is right or wrong about this chemical process.


Now i made a simple mindset.

We all invest about a 1000 bucks or more for a flying camera. Who cares the f***ing battery!?

Just load them up and fly the **** thing and make sure you get it back before the crash.

If the battery losing power you order a new one. Some people have to buy after 18 months and other at 3 years.


If it is a big money issue stick with your point-and-shoot camera (don’t forget to read the battery maintenance manual)


Happy flying to all of you!

It is more of a safety matter too. If you get into habit of start returning at 30% percent, obviously depending on distance too, you are increasing the safety of your flight as you can postpone landing, or withstand sudden long change in wind direction and strength. Also, it depends on how often you fly too. It is quite responsible hobby for newcomer and I don't feel like I need to fly daily, not even weekly. I take it as a videography tool when there is something of my interest that I like to film and transform into more artistic vision by editing the footage. One Air battery is £70, that could be easily somebody's one day wages, if you work in lower paid manual jobs. So to preserve them for as long as possible make a lot of economical sense for many people, it makes environmental sense too.

Also. It could be that by discharging below 20% you are lowering the battery capacity and decreasing your flight time gradually. I might be wrong.