How Detrimental To Leave Batteries Fully Charged?

[RogerDH]

My first post here. I'm new to drone flying but have some experience of Li Ion batteries as I have an electric car and an electric golf cart.
The golf battery recommends always put it on and keep it on charge after every game even if you only did a few holes. My car recommends keeping it to approx 20 to 80% to extend battery life but if your going on a long trip charge it to 100% but use the car straight away! . I'm going to keep two of my mavic mini batteries at around the 3 lights showing whilst not using but have one battery and the controller fully charged all the time. Only time will tell!

With flying weather so uncertain this time of year, that's what I decided to do, too -- always ready to get out and flying on the full battery while the other two charge from a power bank plugged into the hub. I am going to make sure I keep the same battery charged to 100%, so any detrimental effects will only affect that one battery, and if it needs replacement before the other two, that's acceptable for the convenience.

 

[WithTheBirds]

The mini uses metal can type Li-Ion which are less prone to issues such as swelling.
The plastic type Li-Po cells are very prone to swelling which even if the battery is electrically sound, may unlatch in flight and lose power.

The biggest killer is heat. Heat plus full charge is worse.

I don't think one has to go crazy about not going below 10% as there's a margin of safety built in on the % scale so it's probably better to leave it at 10% than 100%, assuming you don't leave it that way so long (like months) where self discharge brings it dangerously low.
The only issue with getting below 20% is having enough power to get home and not auto-land. That and Mini may be more prone to "insufficient power" when charge gets low.

With respect to accelerated loss of usable capacity and the contribution of storage SOC and temperature LiION and LiPO have no significant difference. The metal enclosure jelly roll style LiION obviously can’t swell, at least it won’t to any appreciable extent before a safety valve releases some of the nasty contents. Pouch cells are an advantage here as the slight permissible swelling makes them less of a hazard. It is an advantage rather than a detrimental feature. If you read manufacturer data sheets you will often see stated the permissible increase in pouch dimensions during normal use.

 

[raymacke]

RogerDH 's logic seems to make sense to me. Use one particular battery for the full charge which should limit the damage to it. Also, it will provide some hard evidence to the level and acceleration of the damage as it can be compared to the other two.

 

[softdown]

I've been active on an off grid solar board for almost six years. I've seen so much advice on battery maintenance that I no longer have certainty about many battery related items. Having been a home builder/tool junkie and photographer and videographer I have bought dozens and dozens of lithium batteries.

Bought the Mini Flymore for an anticipated four day adventure chronicling four hoped for climbs in four days. So I just ordered a Penivo Mini charging station. The included Flymore charger only charges one battery at a time per my readings.

This is what I am thinking right now. A great drone opportunity may be irreplaceable. I don't want to miss it because I was coddling the batteries. OK - looked at battery prices expecting $40 or less. Geez - $100?

Now my economics background enters the picture. I suspect they may make a smaller margin on the drone and a large margin on the battery sales. Their advice may prompt avid users to spend hundreds of dollars on - batteries. High margin batteries. Just a theory.

Anyway, I will likely keep mine pretty well charged. Unless their batteries are very unique, and they may well be, one of lithium batteries known advantages is the great leniency allowed in charging and storage parameters.

I feel like half the posts here are about battery maintenance. Recent Discussions Solar battery maintenance as a rule but we are frequently discussing different and new battery technologies. Perhaps I will address drone batteries there some fine day. A few posters are in the battery industry.

 

[RogerDH]

I've been active on an off grid solar board for almost six years. I've seen so much advice on battery maintenance that I no longer have certainty about many battery related items. Having been a home builder/tool junkie and photographer and videographer I have bought dozens and dozens of lithium batteries.

Bought the Mini Flymore for an anticipated four day adventure chronicling four hoped for climbs in four days. So I just ordered a Penivo Mini charging station. The included Flymore charger only charges one battery at a time per my readings.

This is what I am thinking right now. A great drone opportunity may be irreplaceable. I don't want to miss it because I was coddling the batteries. OK - looked at battery prices expecting $40 or less. Geez - $100?

Now my economics background enters the picture. I suspect they may make a smaller margin on the drone and a large margin on the battery sales. Their advice may prompt avid users to spend hundreds of dollars on - batteries. High margin batteries. Just a theory.

Anyway, I will likely keep mine pretty well charged. Unless their batteries are very unique, and they may well be, one of lithium batteries known advantages is the great leniency allowed in charging and storage parameters.

I feel like half the posts here are about battery maintenance. Recent Discussions Solar battery maintenance as a rule but we are frequently discussing different and new battery technologies. Perhaps I will address drone batteries there some fine day. A few posters are in the battery industry.

The DJI official price for Mini batteries is $45, which is pricey enough to make me wish that the 18650s were easily replaceable. That would be less than $15 for a pair of premium cells.

 

[softdown]

The DJI official price for Mini batteries is $45, which is pricey enough to make me wish that the 18650s were easily replaceable. That would be less than $15 for a pair of premium cells.

18650 cells are very affordable. Your post makes me think they made it difficult to replace them. Nothing special about the 18650 though I'm sure they use a quality supplier such as Panasonic or Samsung. But still very affordable cells!

Amazon lists the batteries at $98. Wonder what is going on?

I posted my question at the aforementioned solar board link and have learned nothing at all to date. But I will re-iterate my take that the profit margin, even at $45, is just fantastic. For them.

Keeping them at 80% seems a good compromise but I don't believe my chargers, due here in days, give that accurate of date. Plus that charge data is often off by a significant amount.

The proper challenge would be replacing the 18650. Being a prepper I have a few dozen in cool storage. Suppose I should charge them to half way. Always hundreds of mtce related things to do.
EDIT: Dug out my 36 18650's bought in 2016 and stored cool. Measuring 3.8 volts/cell - I feel that is close to idea for further storage. They are rated 3.7 volts but properly charged batteries measure significantly more than stated voltage. For example, a properly charged and healthy 12 volt car battery measures about 12.8 volts the day after being charged. Should be stored above 12.4 volts to minimize very deleterious sulphation.

 

[softdown]

These Mavic lithium batteries are likely quite unique do to need for very high energy and very light weight. Electric car lithium batteries are composed of:
Lithium
Cobalt
Aluminum
Carbon
Weight is not a such huge concern on a vehicle. A few more pounds makes no real difference.

I have not found anyone who knows particulars about the magic pixie dust poured into drone batteries. My thinking that all lithium 18650's are the same likely could not be more wrong.

 

[RogerDH]

These Mavic lithium batteries are likely quite unique do to need for very high energy and very light weight. Electric car lithium batteries are composed of:
Lithium
Cobalt
Aluminum
Carbon
Weight is not a such huge concern on a vehicle. A few more pounds makes no real difference.

I have not found anyone who knows particulars about the magic pixie dust poured into drone batteries. My thinking that all lithium 18650's are the same likely could not be more wrong.

The Tesla is powered by over 7000 Panasonic 18650 batteries.

 

[softdown]

The Tesla is powered by over 7000 Panasonic 18650 batteries.

They use cobalt which is typically found in more expensive, heavier high performance 18650's. I would bet that drone batteries do not have heavy cobalt in them. I think we need to get away from battery size and look for battery chemistry.

Off grid solar users also generally try to avoid cobalt since the fumes are toxic in the event of a fire. Fires are unlikely but modern decisions often tend to be fear and safety based. Pros and cons to everything.

 

[WithTheBirds]

These Mavic lithium batteries are likely quite unique do to need for very high energy and very light weight. Electric car lithium batteries are composed of:
Lithium
Cobalt
Aluminum
Carbon
Weight is not a such huge concern on a vehicle. A few more pounds makes no real difference.

I have not found anyone who knows particulars about the magic pixie dust poured into drone batteries. My thinking that all lithium 18650's are the same likely could not be more wrong.

I wouldn’t say they are unique- garden variety INR18650-25R Samsung 18650 cels.

You are certainly wrong to the extent you suggested they might prove very lenient with respect to charging and storage.

Go find a data sheet and you won’t need to guess. It is safe to assume that the performance and operating characteristics are shared with any other LiION cell of good quality.

 

[softdown]

Mavic battery pack weighs 3.5 ounces. Two 18650's in a lightweight plastic case bounce between 3.4 and 3.5 ounces. The difference in battery weight between garden variety 18650's is pretty insignificant by most accounts.

I wouldn't be so intrigued but I likely need a group of batteries for doing Colorado's "toughest 4WD trail" four times in four days with four rigs. A lot could go wrong. It is an ambitious idea.

It isn't quite as rough as this description may make it out to be. Lake Como

 

[WithTheBirds]

Mavic battery pack weighs 3.5 ounces. Two 18650's in a lightweight plastic case bounce between 3.4 and 3.5 ounces. The difference in battery weight between garden variety 18650's is pretty insignificant by most accounts.

I wouldn't be so intrigued but I likely need a group of batteries for doing Colorado's "toughest 4WD trail" four times in four days with four rigs. A lot could go wrong. It is an ambitious idea.

It isn't quite as rough as this description may make it out to be. Lake Como

In case I was clumsy in my wording- the Mavic Mini uses Samsung INR18650-25R.

If you are travelling in a vehicle a charging solution probably makes as much, if not fore sense, than the acquisition of additional batteries.

 

[emilford]

It looks like no one has been able to provide a quantitative answer to the OP question. My take on the question was to get an idea of how long a battery would last keeping it fully charged vs keeping it at ,say, 50% charged (all else being equal). I too would like to know. Specifically, If I keep batteries fully charged, how long before I have to replace? On average. If I follow the “optimum” storage recommendations, how long?
I tried to understand and make conclusions from the Battery University site but am not knowledgeable enough.

 

[WithTheBirds]

It looks like no one has been able to provide a quantitative answer to the OP question. My take on the question was to get an idea of how long a battery would last keeping it fully charged vs keeping it at ,say, 50% charged (all else being equal). I too would like to know. Specifically, If I keep batteries fully charged, how long before I have to replace? On average. If I follow the “optimum” storage recommendations, how long?
I tried to understand and make conclusions from the Battery University site but am not knowledgeable enough.

Nobody can give an exact answer, too many variables.

This table from the website you referenced gives a good rule of thumb idea- it correlates with my direct experience from many years of lipo use. My sense though is that newer batteries, while they do suffer accelerated ageing with higher SOC and temp, it doesn’t seem to be to the same extent.

.

 

[softdown]

Pretty on topic discussion of the various 18650 batteries:

Chinese batteries claim to be 3 times better while providing 1/2 as much energy. The Korean and Japanese batteries provide 98% of their claim while the new Chinese batteries provide a dismal 12%.

LG appears to among the biggest bangs for the buck though I do still recommend Project Farm's comparisons of many products that we frequently use. Sometimes we get what we pay for, sometimes we don't.

I'm really not buying into the importance of storing batteries at 40%. Though I am sure we shouldn't try to keep them close to 100% with very frequent charging.

I would bet the drones use fairly standard, though relatively good, 18650 batteries. They are neither lighter nor heavier than the rest. Their profit margin on the batteries is very good. I'm fine with profit margins by the way. That allows them to stay in business, do research and development, and offer some customer service. The drone packages are probably not all that profitable after all is said and done. The batteries are very profitable.

It is a wonder there are not 3rd party batteries by now. Plenty of drone owners seeking more batteries.

Anybody repacked their tool batteries? How hard is it? Good source for the cell connectors?

 

[WithTheBirds]

Pretty on topic discussion of the various 18650 batteries:

Chinese batteries claim to be 3 times better while providing 1/2 as much energy. The Korean and Japanese batteries provide 98% of their claim while the new Chinese batteries provide a dismal 12%.

LG appears to among the biggest bangs for the buck though I do still recommend Project Farm's comparisons of many products that we frequently use. Sometimes we get what we pay for, sometimes we don't.

I'm really not buying into the importance of storing batteries at 40%. Though I am sure we shouldn't try to keep them close to 100% with very frequent charging.

I would bet the drones use fairly standard, though relatively good, 18650 batteries. They are neither lighter nor heavier than the rest. Their profit margin on the batteries is very good. I'm fine with profit margins by the way. That allows them to stay in business, do research and development, and offer some customer service. The drone packages are probably not all that profitable after all is said and done. The batteries are very profitable.

It is a wonder there are not 3rd party batteries by now. Plenty of drone owners seeking more batteries.

Anybody repacked their tool batteries? How hard is it? Good source for the cell connectors?

If have time to read responses you will find I told you which 18650 is used in the Mini (post #30).

Whether you believe LiION is subject to accelerated aging when kept at full rated terminal voltages is irrelevant- it is a known feature if the chemistry. For those who fly very frequently the impact will obviously be less of an issue, it is a real thing though. It is also well established that 40% storage SOC is a great compromise for realising long usable service life of LiION cells.

I wouldn’t consider trying to repack power tool batteries, all I have had apart employed spot welding to terminate cell connections.

I have salvaged 18650”s from power tool packs though, they are usually higher quality offerings given the current demand in use and how much the marketing departments like to quote impressive Ah ratings.

 

[Jamesz]

For me I got a YX parallel charger, I can typically have 4 batteries ready to go within the hour. That's short notice enough for me. That way I can preserve their health keeping half charged and not wait 3hrs+ to charge the other 3.

 

[Jamesz]

The YX charger, plus a regime of having 1 battery fully charged every month, then rotated with the other next month and so on, works well for me.
I wonder why there's never a mention of not keeping the controller fully charged as it is also a Lipo battery ( and takes a while to charge). Any ideas why this should be treated differently?

 

[tnt_flyer]

If i am not going to use drone for 10 days is it necessary to discharge batteries by flying drone or i can charge them through charging hub to 40-65% and then store them?Is it the same thing?

 

[raulmavic]

I wonder why there's never a mention of not keeping the controller fully charged as it is also a Lipo battery ( and takes a while to charge). Any ideas why this should be treated differently?

In fact, I NEVER fully charge controller internal battery. After each flight I recharge it about 50% (three blinking leds)

R.