While reading the specs for the recently announced DJI M30 series drones, I came across this interesting piece of information about its battery:
"The TB30 battery can achieve up to 400 charge cycles within a 12-month period, if it's charged to 90% or higher for fewer than 120 days combined."

Like Mavic 3 battery, the TB30 batttery is also a Lipo type battery, but double the weight (685g) and capacity (131Wh). So I suspect both share the same charge cycle (400), and storage requirement?  

Does it mean we should also try to keep Mavic 3 battery charged to 90% or higher for fewer than 120 days combined each year?

@ DJI Admin/Mod, can we get a clarification on this matter?


Source: https://www.dji.com/matrice-30?site=brandsite&from=homepage

M30 battery specs: https://www.dji.com/matrice-30/specs
Mavic 3 battery specs: https://www.dji.com/mavic-3/specs

While I wont pretend to know the chemical make up of each battery in detail, I think your question can safely be answered just based on basic facts regarding LiPo battery technology. The short answer to your question is YES. LiPo batteries should not be stored at, and constantly charged to, 100% of capacity. This is why the mavic 3 batteries will automatically begin to discharge after about a week. LiPo batteries should be stored at around half charge. In short this simply helps keep the cells healthy. As a rule of thumb you never want to run Lipo batteries to 0%, and as said you never want to force them to sit at 100%. Both of these actions can damage the cells, and the risk increases substantially the more repeated times you do it. For example, if you know you are not going to fly your drone for several weeks, you would want to put them on the charger, charge them up to around 2/3 of the 4 lights, then pull them off - if you have previously flown and depleted them. After a week the battery will discharge itself down to around 60%. Do not throw them back on the charger after this discharge unless you are planning to use them soon. These are just good rules of thumb with LiPo batteries.

-Avoid hitting 0% on the battery at all times, if at all possible. Draining a LiPo to complete depletion can render the battery unusable.
-Charging to 100% to prepare for use is ok, but the cells should not be left to sit at 100% or forced to hold this level of charge for long periods. This will damage the cells over time, reduce their effectiveness, and can cause them to expand and in rare cases even explode or catch fire.

Tornado12 Posted at 3-24 09:27
While I wont pretend to know the chemical make up of each battery in detail, I think your question can safely be answered just based on basic facts regarding LiPo battery technology. The short answer to your question is YES. LiPo batteries should not be stored at, and constantly charged to, 100% of capacity. This is why the mavic 3 batteries will automatically begin to discharge after about a week. LiPo batteries should be stored at around half charge. In short this simply helps keep the cells healthy. As a rule of thumb you never want to run Lipo batteries to 0%, and as said you never want to force them to sit at 100%. Both of these actions can damage the cells, and the risk increases substantially the more repeated times you do it. For example, if you know you are not going to fly your drone for several weeks, you would want to put them on the charger, charge them up to around 2/3 of the 4 lights, then pull them off - if you have previously flown and depleted them. After a week the battery will discharge itself down to around 60%. Do not throw them back on the charger after this discharge unless you are planning to use them soon. These are just good rules of thumb with LiPo batteries.

-Avoid hitting 0% on the battery at all times, if at all possible. Draining a LiPo to complete depletion can render the battery unusable.

I am fully aware of the basic facts about Lipo battery. I am mostly interested in DJI's statement about not keeping the battery fully charged for more than 120 days a year. I wonder how do they come up with that magic number.

On another note, assuming DJI's magic number is correct, if someone fly his Mavic once a week, then fully charge the battery thereafter, this is almost like a worst case scenario -  the battery won't fully discharge in 7 days, and by that timeframe he flies and recharges the battery again, which means the battery is almost always fully charged, 365 days in a year. I suspect a lot of lazy pilots do exactly like that, and not aware of the consequence.

The best practice of course, is to only charge the battery to 2/3 of the 4 lights after each flight, then fully charge it right before the next flight. It is quite tedious, because you have to keep monitoring the battery indicator light to make sure it is not "over charged". For this particular reason, a lot of the 3rd party chargers support storage mode, to charge the battery to 60% exact. I find DJI's lack of support for storage mode in its own charger a serious omission.

These are smart batteries and have a set hibernation charge to preserve the battery as long as possible for the use of that battery. I think but could be wrong, the expected use of the new Matrice is different and the need for the battery to be at a certain power to be ready to go so its likely that battery has been set differently because of the purpose use its needed for.

So I don’t think they have adopted a new strategy for drone batteries , just one for Industrial drones.

jerryway Posted at 3-24 09:32
I am fully aware of the basic facts about Lipo battery. I am mostly interested in DJI's statement about not keeping the battery fully charged for more than 120 days a year. I wonder how do they come up with that magic number.

It is most certainly derived from well known scientific data regarding the chemical make up of the battery. It is the same with any type of technology of this nature. This is why batteries also have charging and storage temperature parameters. Its based on scientific knowledge of the elements involved in the product. There is likely a very sophisticated and scientific reasoning behind the specificity of the 120 days, but for us end users, we can stick to the basic rules of thumb regarding LiPo battery technology. Reducing the time the battery sits at 100% is just a given with all LiPo batteries. If anything, I would expect the Matrice to be more forgiving, with more advanced manufacturing. We can see wider temperature parameters for example in the specs between the two batteries. So if you wanted to try and draw some possible conclusions you could say that the mavic 3 battery should probably be charged to over 90% LESS than that of the matrice. But there is no hard cut off on these things - it is all on a graduated scale. Much like a lightbulb has a specific lifespan in hours - some will go out sooner than others, some will last much longer than expected, some will also die prematurely. A lot of parameters go into each unit.

I would say follow good practice based on the LiPo technology.

jerryway Posted at 3-24 09:46
On another note, assuming DJI's magic number is correct, if someone fly his Mavic once a week, then fully charge the battery thereafter, this is almost like a worst case scenario -  the battery won't fully discharge in 7 days, and by that timeframe he flies and recharges the battery again, which means the battery is almost always fully charged, 365 days in a year. I suspect a lot of lazy pilots do exactly like that, and not aware of the consequence.

The best practice of course, is to only charge the battery to 2/3 of the 4 lights after each flight, then fully charge it right before the next flight. It is quite tedious, because you have to keep monitoring the battery indicator light to make sure it is not "over charged". For this particular reason, a lot of the 3rd party chargers support storage mode, to charge the battery to 60% exact. I find DJI's lack of support for storage mode in its own charger a serious omission.

It won’t affect your battery if you charge it to 75% then leave it to go into hibernation. But certainly its not safe to fly on a battery that has begun hibernation. In fact as a rule I always fly a new battery for every new mission.