How long can you leave your lipos fully charged without damaging them? 

I think they might degrade 5% when left 30 days charged the first time, but if you leave them the second time charged for 30 days they don't degrade another 5%. Maybe another 2% or so. Im a professional charged battery procrastinator, for many years now. I have packs that are 4 years old and have been left charged for 2 weeks (thats my max) for at least 5-6 times and they are still "fine". I mean they don't feel like new but i get a meaningful flight from them still.

From what I've read, the lithium dendrite growth over time that cause the reduction in capacity. Overcharge and over discharge seems to quicken this effect and when the dendrites reach from one side to the other, you get a short and a fire. The mechanism that govern the rate of growth of this stuff seems like a hot topic in Li-ion battery research for improving performance. Very cool stuff.

I swear this is the big question that's been on my mind here lately. You rock!

Really great topic to discuss, I had to click. Sometimes I leave my lipos charged for three or four days but I worry more about how volatile they are in that time. Not how fast they degrade from that time, holding full charge. Thanks again for the great content and everything you do for the fpv community 🙂

Great job at voicing that way of thinking about it.

You guys are amazing with everything you guys do and still take care of your kids I know how hard it is with my one and three year old boys.

Awesome Video...I've been thinking a lot about this lately. Good information JB!

Good info Joshua. DJI has even developed a self discharge on there smart packs now. It’s cool that they go into auto discharge after a few short days. Certainly saves me from having to worry about it. I often charge up the night before and wake up to rain or unpredictable circumstances leaving me leaving my drone in its flight bag for a few days.

It’s like you read my mind, I was just wondering about this recently, thanks J.B.

Kemosabe, thanks for addressing this fact on Lipo batteries as U & I touched on this several weeks ago as my kawd flight schedule is frequently interrupted due to my on-call business vs free-time. Again, excellent food for thought for many.

A 4.2v lipo bomb has more damage potential than a 3.8v lipo bomb. Probably also worth noting

Thanks for the information man. I do the same thing for my crawler. Lipos last SOOOO MUCH LONGER than the NiCads I grew up with in RC. 3hrs run time, I run outa stuff to climb. 2 packs are 3 years old and balance charged for great performance.

I think you answered a really on topic question here! Great video!

I love your knowledge on these batteries I just subscribed and hit the bell. Keep up the good work Keith

I am also a firm believer that the better the cell the less keeping them changed is a problem.. I have one single 3s Lipo (2600mah) that I have had for 10 years for an airplane.. and yes it is low C compaired to drone batteries now a days.. but that thing sat chaged for 5 years at 4.2v and I recently cycled it a few times in that same plane and it was perfect..

Thank you Bardwell.

Very good points! I am very "relaxed" about how long I leave my batteries at full charge (I like to have them ready to rip) and I am unable to tell any difference in performance. That doesn't mean there isn't a performance degradation, just that I'm not bothered by it. 👍

Joshua, Good info on the batteries. I recently did a test with my phones lipo, which took 2+ years to complete. I read that, like you mentioned, a lipo's ability to hold a charge was reduced to the 70% arena after 300-400 charge cycles. BUT, just modifying two parameters would increase that life to 1700 - 2000 charge cycles. Now, to be fair, a charge cycle is defined as charging back 100% of the battery's capacity. ie , a 4S 1550 would need 1550ma of power charged back in to be considered 1 charge cycle.. Two 775ma charge sessions would be considered only 1 charge cycle, as well. The two parameters I mentioned are 1) Limiting the cell voltage to 4.00v/cell (or 80% of the battery's capacity) and 2) limiting the amount put back into the pack, at any one time, to 20% of it's capacity. The second would require multiple charge sessions to get back to the 80% mark. Funny, it's the 80/20 rule that we see in business all the time. 80% charge cap, and a max of 20% at any one time. You might ask "What do these two things accomplish?" 1 - The 80% rule addresses the phenomenon of the battery chemistry crystalizing in the cell at anything greater than 4.00v. Well, it actually occurs at all voltages but what experts have learned is that it accelerates at voltages above 4.00v. 2 - Limiting charge amount, only adding 20% at a time, addresses the second killer of lipo's, and that's heat. When you charge back >20% the battery naturally starts producing heat internally, which also accelerates the crystalizing phenomenon spoken of earlier. So, back to my phone test. I bought a new Samsung Note 9 in Sept 2018. I installed an app called AccuBattery, which tracks your battery's health in terms of capacity, and will let you know what its capacity at any point during its life. It will also alarm when it reaches the maximum capacity that you set it to. Mine was set to 80%. By changing the way I charged, limiting it to 80% capacity (the Notes have a 4000ma pack so I wasn't really limited at being at 80%) and by "bump-charging" on a wireless charging pad several times a day, I was able to trade in that phone at the 2 1/2 year mark....and AccuBattery said that my batteries capacity was still at 87%. The second owner of that phone got a bargain, if you ask me, because used phones typically have batteries that have been "rode hard and hung up wet", and you never know what their life is. Kind of like a used car. Getting a phones battery replaced can be expensive. Conclusion: I'm glad we don't fly phones!! We can toss a mini quad lipo and replace it once we feel the sag coming on sooner, knowing the pack has seen better days. Thanks for the video, as I've often wondered about how long I can store before I start crystalizing the chemistry.

very useful for newbies and veterans

I'd say I agree with your theory and time lines 👍 nice work jb

Very helpful and makes sense! And cute little kid there!!

Thanks Bardwell for ur opinion 👍im so glad i learned a lot about lipos and liions before starting Fpv :D

I never leave my batteries fully charged for more than a day and I have used some lipos for 4 years which performed just fine. I don't fly bandos though. Nice side effect: You can always parallel charge your lipos before going to fly because they are all at 3.8V.

lookin buttery smooth professor!

Was just discharging batteries when this popped up. Very insightful, thank you!

Thank you!! The best question answered!!

Great info. Thanks, Joshua.

Loved this video, thank you!

I tend to agree with your cumulative hypothesis for full charge degradation. And I'm confident I do the most damage to my batteries when I accidentally overdischarge them or smashing them, not waiting a few days between charge to discharge.

Beautifully explained, thank you sir O7

Thanks! This was just the video I needed as I have 8 fairly pricey Cinelifter batteries and was just about to buy some of the smart lipo battery dis-chargers since I may only film a job once a week, and was debating how long to let them go before I discharged

My thoughts exactly. Great info!

Thanks for this great info Joshua. I just pulled my quads out of the closet last night, after two years, and remembered I hadn’t discharged my batteries to storage level before they got boxed up when we moved. Two of my Tattu R-Line 850 4s batteries were completely dead, and two of my Ovonic 1550 4s batteries each had a single cell below 0.5 volts. The rest seem to be fine, and have discharged down to 3.6-3.8v per cell on their own. I was able to resurrect both Tattu batteries using the NiCd direct-charge trick to 13v, then balance charging the rest on LiPo. They’ve both held charge across all cells overnight so far. Fingers crossed. I was also able to resurrect the single cells in both Ovonic batteries by charging them through the balance lead using NiCd to 3.5v, and then LiPo 1s to top them off. Now I’ll just have to see if performance has degraded much. The batteries didn’t have a whole lot of usage before being stored so I’m hoping for the best.

100% agree, as example my Mavic Batteries do auto discharge after 3 Days, BUT they are very likely never to be broken in a crash, in fact, the oldest one is rocking 472 cycles and i still can fly 14 minutes with it. but for the freestyle Lipo's if i go out with the gang and somethings some along the way .. i just leave them and use them up over the span of the week flying them to the storage voltage (ish) so the charger just need minutes to finalize the storage. i repeat this until 4 packs are left (always have 4 fully charged)

Small addition for batteries that are brand new: These still contain a certain chemistry that protects the batteries before they are charged for the first or second time. The fact that these arrive at 3.8V per cell is no proof that they can therefore be stored for ages later, I think. I was once told by a GensAce employee that correct and slow charging should be much more important at the beginning. But in the end it's all about having fun and batteries usually only last one season for me anyway. 🤣

Really appreciated the point that putting them back to storage is a cycle that comes with it's own wear and tear. Definitely something to keep in mind

I have Lipos from 2017 (yes, 4 years old). I have religiously “storage charged” them 10 minutes after each flight and they have only been fully charged for a maximum of 2 hours (I fly at my house) during their lifetime. Their capacity is around 80% of what they were when I bought them but they are still going strong and I still use them. If you keep your batteries in storage charge for most of their “sitting around time” then they will last.

Great basic info. Worth noting that the level of degradation between full and storage voltage is not linear. Reducing the voltage from 100% to 90% or 80% can greatly decrease rate of degradation, without having to do a full round trip to storage voltage and then back up to takeoff voltage. Not mentioned is the speed (or amps used) to charge and discharge cells. The higher the more degradation occurs. With drones, discharging almost always occurs at hight amps. Being bit more gentle at end of a charge, and recharging can reduce some stress on the cells. Degree of voltage sage is a general indicator of how much cells are being stressed. The other important factor is heat. Heat is bad for cells, particularly when are fully charged, as it amplifies all the bad chemical reaction in a cell that causes it to degrade. Simple tips, is try not to leave charged cells in warm car, or sun. Letting cells cool before charging. A good reference to learn is "battery university". It covers both basic stuff, but also gets into hardcore details should anyone want a deep dive into chemistry and physics.

Great topic! , wondered about that alot my self 👍

Thank you for this!

I recently purchased an ISDT discharger because I'm not good about discharging my fully charged batteries when I have them. Now it is so easy.

We have some Turnigy Nanotech lipos that I believe were purchased around 2015-2016. They haven't been used all that much and are stored at around 38%. Seem to be perfectly fine

Thanks for your explanation 👍 I am so jealous that you still have Tshirt weather

Thanks!

Helpful vids man even for us car guys 👍👊

I left my lipo 1.3 4s at storage for over 2 years...i thought i lost them in a move. And this christmas i was going through bins for decorations and found it, they are still at 3.8 and im charging them now. Im so excited.

Storage voltage is important. Landing the quad early is good if you dont go home and charge when done flying.

Thanks for this..good to know!

Great video man very helpful

Same here. 1 or 2 days are not a big deal. But after 3 days of bad weather and not flying i always put them back in storage.

Exactly what I was needing perfect 👌

The question becomes: What is the relative impact on battery life of a charge/discharge cycle vs. being left charged for 24hrs (or some multiple thereof). Knowing that would help to guide the question of whether to leave charged until use or storage (dis)charge them until next charge & use. This was a small video that gave us a few answers but left some perhaps even bigger questions. Your stated conclusions do tend to mirror my own, thanks for the confirming/supporting opinion. J.P.

great info, thanks.

thanks

I was just going back and forth with my flying buddy about this yesterday! He left his fully stored for a few months when we got rained out, I said they would be weak all day but he couldn’t tell a difference. I never realized charging and storing also wears out the lipo

Great video. Question: how do they define "performance"? Voltage sag? Overall flight time? All of the above?

It’s nice the spectrums g2 batteries have an automatic discharge built in and you set the for 72 hours Down to 12 kinda of a cool function

Thanks Joshua... very helpful video. I been trying to find someone (anyone) who can give me an "honest" answer to the question of how long batteries can be left fully charged and this is the closest I have ever gotten to that answer

ThankU 😊👍

Thanks buddy,,, very helpful

The ugu gaga worked, I subscribed. yay!

I agree with you, I think it’s a cumulative effect. My goal is always to keep my batteries charged as short a time as possible, and keep them at 3.8v as long as possible. I think following that rule will extend the life of the battery.

I charge - discharge/recycle my lipos to my 4S3P 21700 "Powerbank". This is quick and the Lion pack didn't notice this little amount of energy. I have 7-8 years old lipos and they are still fine after hundreds of cycles.

Awesome, Joshua! Thanks a lot! 😊 I wonder the same about lithium ion batteries... Like the 18650s. They seem to be able to hold power for much longer, but... Other than that it's a mystery to me. Anyway, stay safe there with your family! 🖖😊

Your the Best! 🤘🏽

When at storage charge also store at 5degC. I have batteries from 2007 which are still over 80% rated capacity thanks to living in a beer fridge.

Totally agree, its a chemical process that happens while in a high charge state, even if you only have the pack fully charged for an hour it still happens.

This came at an awesome time as I have 1 battery I forgot I had charged and can't really discharge since my drone is awaiting repairs. I'll probably retire it since 2 cells literally won't budge from 4.2v while the other 2 are at 4.05. Will also buy a proper battery charger (that can also discharge)

Great video thank JB. some times i charge all the lipos then when i get back home I really dont do nothing to them just put them in the amo box then a few weeks later I storage them I dont fly every weekend its just been lazy

Been in that situation alot of times charge the night before only to wake up to rain(gotta start checking the weather forecast). But the most time I leave my battery's charged is 3 days after that ill charge them back to storage charge. Joshua you should do a review on the bigdaddy battery's and the zees. They are cheap but hold up well.

Thanks JB. Which is worse: leaving the battery at full charge or leaving at around 15% charge, say around 14.9v for 4s?

Joshua, How important is the internal resistance(ohm) of batteries？ During changing, an ISDT charger shows resistance per cell. Some shows 10-15, and other shows 20-30. Could you tell beyond certain value could be dangerous or not efficient to use anymore, etc? Additionally I wonder if we can connect 2 lipo batteries with parallel to Drone. For instance, I have 4s 450mAh batteries. Instead of buying new 900mAh for a bigger drone, I want to reuse 450mAh x 2. Is that possible? or explode drone?

There's also temperature. I had a PDA that I kept fully charged in a hot environment and the battery wouldn't charge in less than 6 months. The worst thing is to over discharge, next is to keep too full at high temperatures.

So here's a question re the DJI FPV drone: DJI has no provision for charging or manually discharging to storage voltage. So, after I fly, is it better to leave the battery discharged or let it cool then charge it and let it discharge as per DJI's inbuilt discharge?

What about HV charged batteries I wonder? My guess is that performance degrades much faster. HV whoop batteries don't last all that long, but there are other factors that degrade their performance (like overheating) so it's hard to say without more data.

In re smashing your batteries: That's why I switched to Floureon batteries. They have little plates in them. They're heavier, but after chopping one battery in my props and bashing a Tattu into the ground until it broke, I got the "armored" Floureons. They perform decently too, but my charger doesn't think they hold balance well at all. Better than those cheap pair that one just decided to go up sitting on my table. Left a burn spot. The other one has a lame cell, but interestingly my charger has no issue with its balancing.

For those of us that don't churn through batteries (especially me with RC crawlers) keeping them as healthy as possible can save money over the life of the battery. Especially when I have 2-3 batteries for each crawler and one battery gets through several hours of crawling.

I use those cool LiPoSuction things that discharge the battery to storage super slow. very convenient. I have a set of batteries almost 3 yrs old and still going strong. My previous set of batteries that i left at full charge for a couple days each week only lasted about 9 months. So I am now under the impression that cycling the battery is better than leaving it at full charge. Just my one opinion though.

Great thank you In what C rating can i discharge a 6s 1300mah battery with D6 pro dual charger? Can i go 2 or 3 C? 1 C discharge to storage takes long time

I usually store my lipos on 3.95v.(70%) it's pretty nice because you are ready to fly much quicker.

Thanks for saving my new batteries. Totally forgot to discharge them last week.

One way of looking at it using the available information... but over a decade testing lets me say temperature during storage just above freezing almost stops the clock... and GNB says to maintain capacity to store their HV Lipos just above their wet charge state (somewhere just above 3.0v) and NOT at 3.85v as most people say repeating what they have been told.

I know this, but I didn't used to.... I left 3 batteries of the same type, Turnergy Graphene Panther ones, for over a year... 2 are still good and one is a bit pants... But one was always a bit pants. I have heard from other RC nutts that it doesn't matter, but personal experience tells me it matters a bit. I still use the Turnergy batteries today and only seem a little off their best.

I've just learned to accept that 60-80% is the real "maximum" to avoid potential fireworks shows. I store my phone/vape in a backpack while travelling (outer pocket), and wrapped in a fire blanket at night. Old cells are fully discharged (at least as much as they can be), and placed outside in a ventilated metal toolbox (ventilation to prevent explosions). Until I get around to disposal. Glad to see everyone waking up to this new reality, hopefully in a few years Lithium will just be a forgotten nightmare due to better/safer tech.

Just switched to 6s, brand new batteries , so , great timing sir! AND he’s a dad , who knew. Lol. Future fpv’r?

The same 'useful life budget' concept applies to discharging them at or above the 55C effective discharge rate - LiPos are incredibly impressive (the LiHV chemistries too), but realistically you have about an hour of useful life at the higher discharge rate, but in reality that's actually pretty excellent because it's a whole lot kinder to be at anything other than wide open throttle. This is why a two-year old battery with about 80 cycles that has spent probably a touch over month charged up gets transitioned to the practice bin, because it's about halfway through its total useful life but no longer has the edge to be a racing pack or the one to use when a shot really matters... but it can push a lot deeper. On the rare chance my packs to live to the 150 cycle (4+ year) point without mechanical destruction, then they get to be ground station power sources off BECs, because if I kill those I won't really be sad about it.

is storing a lipo at 4v/cell better than full charged or is there a only very small window around 3.8v where its good to store a lipo.in other words, is storing a lipo at 4v/cell just as bad a full charged? i dont always have the time to storage charge my lipo all the to 3.8v

how soon do you return a discharged pack back to storage charge after flying ?? next day ? or soon has possible?

Smart batteries have internal preservation discharge circuit.

So - leaving em fully charged reduces the capacity to hold charge - vs packs with bad Internal Resistance (IR) which have reduced capacity to deliver the charge they have. I've been storing some packs fully charged for too long now - and I note that some cannot be fully charged any more - they instead peak out during charge at 4.10v for instance, rather than at 4.20v. But some still have low IR. Learned something new today. You can reduce the capacity to hold charge (leave em fully charged all the time), and you can reduce the capacity to deliver charge (run em down to 3.0v a few times - I think that will do that)

Then would it make sense to not charge your battery right after flying but to wait until you're ready to fly again?

Hi Joshua! There's an opinion, that's it's better to store lipos in fridge. This is because the batteries lost their capacity cause of chemical reaction, and when low temperature the reaction goes slower. That would be great if you test that. Because for me its easier to drop my batteries in fridge instead of discharging them if for example i want to store them one week before next weekend. Thank you!

What about charging at half c rating? I balance charge at half c but many say 1c as recommended by manufacturer is just fine too.

I would say it’s all about your own comfort zone on how long you keep your batteries fully charged.I my self won’t go more than a week.and have never noticed a difference.I would also say that it depends on the quality of battery you are using..there are certain name batteries I’ve used that wear out a lot quicker than others.in the end as long as your comfortable with the way you take care of your batteries…..

I use g.n.b and I always leave em fully charged .I never noticed any difference .this is interesting because I thought if they sat and went to low that would harm them

useful topic 👍👍

Is there a fire risk leaving batteries at full charge or is the fire risk primarily whilst charging?

From what I have found regarding leaving a lipo fully charged for a week an then fly them. Ovonic lipos will keep there ability to be useful over time. Now cnhl lipos really don't an begin to degrade after a few days of being left charged. I have also found that the high mAh of a lipo seems to degrade the lipo fast than a lower mAh lipo...2200mah -850mah, My Rdq lipos seem to do this. However, my pyrodrone graphene lipos seem to do alright which surprised me. Being a resident of Washington state, rainy days with the wind an cold, I try to charge my lipos two days before planning a flight.

Can I fly the battery up to storage voltage and just leave it? When I finish flight, the battery after unplugging is around 3.8V per cell, so it is storage voltage. Is it ok for the LiPo batteries or is it better to use them more and then charge to storage voltage?

How long can you store them at storage volts in the fridge for example?