Battery Shelf Life

[andrew124C41]

After replacing my E2P V2 with a RTK rugged bundle, I have 2 extra new batteries. I have 3 with just a few hours and now another new one. I don't think I need more than 4 batteries to rotate or use when I need that much battery time.

My concern is just letting the 2 new batteries sit on a shelf until the others wear out.

Autel tells me they don't like them just sitting around so I am considering selling them.

Anybody have any experience with this?

 

[GFields]

I would suggest selling them. If you leave them laying around they will eventually go bad and won't be able to charge them.

 

[andrew124C41]

I use a lot of lithium ion chemistry cells and generally, as long as they are kept above their respective minimal voltage thresholds, they last a long time. I have some 18650s that I started using in 2015 that are still good.

But, the warranty is only good for a year. I don't think I need more than 4 batteries so you are right.

 

[herein2021]

I use a lot of lithium ion chemistry cells and generally, as long as they are kept above their respective minimal voltage thresholds, they last a long time. I have some 18650s that I started using in 2015 that are still good.

But, the warranty is only good for a year. I don't think I need more than 4 batteries so you are right.

The newer LiPos are really bad, and the higher the capacity the faster they go bad. A good rule of thumb for high capacity LiPos is 2yrs or 100 cycles whichever comes first. The 18650's are no comparison to the high capacity LiPos, they aren't even the same chemistry (Li-ion vs Li-po).

With that said, sure some people have good luck with their LiPos, mine for example are almost 2.5yrs old and still have the same capacity as when I got them, but I have also had DJI LiPo batteries that started swelling within 6 months. I think mine are mainly lasting so long because I am typically in the air for less than 5-10min to get the few seconds of aerial footage that I need for the project.

Heavy flying with deep discharges, or sitting on the shelf for months at a time will greatly shorten their lifespan.

 

[Detritalgeo]

You can keep them on the shelf but the battery protection circuitry draws a few mAh so set a reminder for yourself to charge them back up to 50-70% every 3-4 months.

 

[pedals2paddles]

Autel tells me they don't like them just sitting around so I am considering selling them.

I may be in the market for some additional batteries if you decide to sell them.

 

[andrew124C41]

I may be in the market for some additional batteries if you decide to sell them.

I found someone locally who will give me close to what it will cost to replace them in the future. For me 4 batteries is enough especially since I can recharge in the road with a 50 amp hour lithium iron phosphate battery. But, thanks for the offer.

 

[uas_gian]

Just as additional info. I have 8 Evo 2 battery packs.

Yeah it is too much for my current drone activity, but I had some concurrent jobs in the past and needed to be able to fly some hours while 4 batterries were on left the charger.

Also tried selling some earlier, but no one reacted to my adds, so I kept them after all.

I still rotate all 8 batteries today and use a system of color labels to know what set was used last and what needs to be used next. However the oldest set of batteries I have were produced 2020 and those two are still performing better than some of the newer ones. None of them are failing yet.

I do recharge them once every 2 or 3 month even in winter time when I usually don't fly the drones.

Keep your batteries in a safe place and at mild temperatures when not being used, I guess this is the most important factor for a longer life.

 

[herein2021]

Just as additional info. I have 8 Evo 2 battery packs.

Yeah it is too much for my current drone activity, but I had some concurrent jobs in the past and needed to be able to fly some hours while 4 batterries were on left the charger.

Yeah also tried selling some earlier, but no one reacted to my adds, so I kept them after all.

I still rotate all 8 batteries today and use a system of color labels to know what set was used last and what needs to be used next. However the oldest set of batteries I have was produced 2020 and those two are performing better than some of the newer ones. None of them are failing yet.

I do recharge them once every 2 or 3 month even in winter time when I usually don't fly the drones.

Keep your batteries in a safe place and at mild temperatures when not being used, I guess this is the most important factor for a longer life.

One consideration for if you have a job that infrequently comes along like that that needs far more batteries than your current setup is to rent the batteries. I had a client contact me about covering a golf tournament and they wanted the drone to provide a live feed nearly continuously for the entire tournament. I would have needed 10 more batteries than I currently have; so I found 3 places at the time where I could actually rent the batteries.

In the end they didn't have the budget for what they wanted to do, but it was a pleasant surprise finding out that I could rent the EVO II batteries if needed.

 

[andrew124C41]

One consideration for if you have a job that infrequently comes along like that that needs far more batteries than your current setup is to rent the batteries. I had a client contact me about covering a golf tournament and they wanted the drone to provide a live feed nearly continuously for the entire tournament. I would have needed 10 more batteries than I currently have; so I found 3 places at the time where I could actually rent the batteries.

In the end they didn't have the budget for what they wanted to do, but it was a pleasant surprise finding out that I could rent the EVO II batteries if needed.

Where can you rent drone batteries.

 

[uas_gian]

In Europe there are less and less locations that offer or deal with Autel Robotics items. two years ago I could buy two Fly More Kits from a Spanish company that was abandoning the Autel brand. Back then I paid 450 + tax + shipping for 2 kits in a sale, this added 4 more batteries to my two drones plus some spare propellers and the charging hubs. So when just counting for the batteries it basically was sold at half price and the extra hubs, propellers, shoulder bags were a free gift ton top. I guess I got lucky.

 

[herein2021]

Where can you rent drone batteries.

One of the vendors here @advexure said they offer Autel batteries for rent although it is not well known, at the time I was going to use Blue Skies Drone Rental for the project.

In Europe there are less and less locations that offer or deal with Autel Robotics items. two years ago I could buy two Fly More Kits from a Spanish company that was abandoning the Autel brand. Back then I paid 450 + tax + shipping for 2 kits in a sale, this added 4 more batteries to my two drones plus some spare propellers and the charging hubs. So when just counting for the batteries it basically was sold at half price and the extra hubs, propellers, shoulder bags were a free gift ton top. I guess I got lucky.

It does seem like Autel has really lost the plot with their customers. All they seem to do lately is pump out tons of mediocre overpriced products without fixing any of the issues with their current products. Meanwhile DJI just keeps getting better and better (but their geofencing gets more invasive).

 

[uas_gian]

One more factor that we pilots cannot control regarding to our batteries is, the outside air temperature. After reading all this I am wondering how important it is to reduce the flying time on sunny potentially warmer days, compared to flying more minutes in cold air. In other words, could it be insufficient air cooling that starts the the swelling of the cells prematurely?

I will now get a thermal gun as thermometer. Since I am already keeping a detailed log for each battery, I will start writing the temperatures down after the drone landed and see if those batteries failing earlier had occasional higher temperatures after being in the air, compared to those that keep working for more than 2 years. It will take a while before I can present my statistics.

 

[Deleted member 14246]

The newer LiPos are really bad, and the higher the capacity the faster they go bad. A good rule of thumb for high capacity LiPos is 2yrs or 100 cycles whichever comes first. The 18650's are no comparison to the high capacity LiPos, they aren't even the same chemistry (Li-ion vs Li-po).

With that said, sure some people have good luck with their LiPos, mine for example are almost 2.5yrs old and still have the same capacity as when I got them, but I have also had DJI LiPo batteries that started swelling within 6 months. I think mine are mainly lasting so long because I am typically in the air for less than 5-10min to get the few seconds of aerial footage that I need for the project.

Heavy flying with deep discharges, or sitting on the shelf for months at a time will greatly shorten their lifespan.

DJI LiPos swelling after 6 months sounds like a major defect. Was it left completely discharged? I've been flying FPV for several years now and have never had battery swell after 6 months, let alone 2 years. Now, I have on several occasions killed capacity by abusing the batteries and pushing them down to 3.0V, but as long as you respect the limits and land at around 3.5V, they last many many cycles.

Regarding Autel, it seems like they have some post-pandemic QC issues. Seems like the radio chipset wasn't the only thing to change in the later revisions, and it makes me think V1 is still the superior version.

One more factor that we pilots cannot control regarding to our batteries is, the outside air temperature. After reading all this I am wondering how important it is to reduce the flying time on sunny potentially warmer days, compared to flying more minutes in cold air. In other words, could it be insufficient air cooling that starts the the swelling of the cells prematurely?

I don't think that would be the case. As long as you're not leaving your batteries directly exposed to the summer sun for extended periods of time, they should be fine. Likewise, cold air will actually shorten your flight time, so pushing for more flight time during winter actually discharges your battery further.

 

[uas_gian]

I don't think that would be the case. As long as you're not leaving your batteries directly exposed to the summer sun for extended periods of time, they should be fine. Likewise, cold air will actually shorten your flight time, so pushing for more flight time during winter actually discharges your battery further.

I never expose my batteries to extreme temperatures and none of my Evo 2 batteries show signs of failing but the newest battery is soon to become 2 years old. Only the large differences in battery life reported in this forum, made me wonder if there might be other missing factors involved. For example you fly you drone mainly in Florida compared to Canada, or in Europe this would mean operating in Spain vs Sweden. This doesn't imply flying only in summer or winter, but it's food for thought. Then I ask myself, is the Evo 2 vs the Phantom 4 maybe not as effective in cooling its battery down on a hot day?

(I am based in the north or central regions of Europe, on average I fly with mild outside air temperatures)

 

[herein2021]

I never expose my batteries to extreme temperatures and none of my Evo 2 batteries show signs of failing but the newest battery is soon to become 2 years old. Only the large differences in battery life reported in this forum, made me wonder if there might be other missing factors involved. For example you fly you drone mainly in Florida compared to Canada, or in Europe this would mean operating in Spain vs Sweden. This doesn't imply flying only in summer or winter, but it's just a thought. Then I ask myself, is the Evo 2 vs the Phantom 4 maybe weaker in cooling its battery on hot days?

(I am based in the north or central regions of Europe, on average I fly with mild outside air temperatures)

I fly in the stifling Florida heat year round and mine are lasting around 2.5yrs so far with no signs of problems. I think when it is in the air the 4 big fans also known as propellers keep the batteries cool. The biggest problem with the heat here is leaving them in your car. I go to great lengths to try to schedule jobs in ways where the drone and batteries are not sitting in my car and I try to park in the shade of a building or tree when I do get to the project site. Car internal temps can reach 130+......I can only imagine what that does to battery life.

I also have 4 batteries, but if I think I can get away with just one or two for the project then that is all that I bring with me. I've had a few close calls since I bring so few batteries but so far it has worked out for me. I also keep the case withe the additional batteries in the shade of a tree or the shade from my car if no trees are around while flying....every little bit helps.

I plan on buying a white towel this year to cover my other cameras and the drone case with when there are no trees around; that's an old ENG trick that I've seen reporters use to keep their cameras cooler in direct sunlight.

 

[ADOC]

I'd keep all the batteries, knowing you can fly a lot more when you need to.
What I do with my devices, and GoPro is a good example for me, is number each battery and follow usage via the numbers.
Lets say your one and one and only battery lasted 2years, and then you found replacements were unavailable.
If you had 2 batteries, then sharing their use gives you 4years of usage.
Everyones usage is different.

 

[herein2021]

I'd keep all the batteries, knowing you can fly a lot more when you need to.
What I do with my devices, and GoPro is a good example for me, is number each battery and follow usage via the numbers.
Lets say your one and one and only battery lasted 2years, and then you found replacements were unavailable.
If you had 2 batteries, then sharing their use gives you 4years of usage.
Everyones usage is different.

Just keep in mind that with LiPo's they typically go bad after 2yrs or 100 cycles.....whichever comes first. So, for example you couldn't buy 8 batteries and expect 16yrs of use; since all 8 batteries would still hit that 2yr mark at the same time. Unfortunately, its a no win situation when it comes to drone batteries, all you can do is use them for as long as they happen to last.

 

[ADOC]

Heres some science on Lithium batteries. Theres a lot of Factors involved once you look into it.
Theres some interesting new batteries coming in the future, which are claiming upto 4x the capacity. Now that would be nice!

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

 

[herein2021]

Heres some science on Lithium batteries. Theres a lot of Factors involved once you look into it.
Theres some interesting new batteries coming in the future, which are claiming upto 4x the capacity. Now that would be nice!

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

Yes I have studied scientific research on them many times over the past 20yrs or so. I've been using multi-cell LiPos since the RC days. Funny thing is, in that entire time there's always been "something better" right around the corner and it has yet to materialize. Everything from aluminum batteries to honeycomb layouts. It takes many years to bring new battery technology into production so I wouldn't hold my breath.

Also, I guarantee you that once something new does actually come out, we will all discover the next weakest link from flying continuously for so long; my bet is the ESC's will burn up.