How not to ruin your drone batteries (with a smart plug)

[mdrm_mavpilot]

DJI uses maximum energy content from the High Volt batteries, so that they fulfil the marketing hype for staying in the air as long as possible.

Batteries can end up as the most expensive item if you abuse them. Eventually, all rechargeable batteries are doomed to become problematic, the real question is "how can I keep the probability my batteries fail at a minimum".

Correct me if I am wrong, but the three main issues are temperature, and low and high voltages.
Low voltages are not (in my humble opinion) the real issue, as DJI does forced landings before this becomes a bad habit.
High temperature is an issue, which is indicative that the batteries internal resistance is too high (heat production = I²R). Trying to fly with low amps isn't really something that can be monitored. Heat is also produced at higher voltages in the final stage of charging the battery. Bad charging is, in my opinion, the main cause.
Lastly, high voltages is something that can be controlled, and it is rather easy. It does means sacrificing energy content because you will don't reach 100%, which is really just a number DJI has predefined for you. There are many studies showing that when batteries are charged up to high voltages, the life time is significantly lowered. Studies show that the high voltages break down at least one electrode, and cause lithium dendrite formation.

proposed solution:
Use a cheap smart plug to switches off the charger in the final charge phase, before higher voltages are reached. "highly volatile batteries" are avoided.
example:
I use the "Shelly Plug S" smart plug (about €20). It measures power usage and can be set to switch off or on under certain conditions. It is controlled via their app. There are many WiFi power monitor plugs, depending on your market.
The smart plug app tells me whilst charging Mavic 2 Pro battery, the charger plug draws a maximum of 65-70 Watts power. During the last 15% the charger throttles down the amperage and power (all modern charges do this, this is standard charging procedure).
I set my smart plug to "switch off" when it is 1 minute under 62W (a few Watts under the charge starting power). I also get a message on my smart phone, so I know exactly when the charge is completed. I reach about 85% capacity with this setting.

I have been doing this for about a year with my Mavic2Pro, and on other settings with a Mini 2. I am still flying with my original batteries.

Hope this helps. It will not work on a charger that charges multiple batteries at once, because the power is shared across the batteries.

 

[StantonZ]

Correct me if I am wrong, but the three main issues are temperature, and low and high voltages.

proposed solution:
Use a cheap smart plug to switches off the charger in the final charge phase, before higher voltages are reached. "highly volatile batteries" are avoided.

You are correct, but your solution (while original) is the "right" thing for the "wrong" reason.

The real issue with (Lithium) rechargeable batteries is the length of time they remain at low and high voltages, which can be solved very simply by charging your batteries just prior to using them (while allowing time for them to "cool", which addresses the temperature issue). In fact, a full charge allows for cell balancing and calibration of the BMS (something the average person wouldn't be aware of). Even with your approach (halting charge ~80%), these battery packs will self-discharge (after a few days) to around 50-60%, so you're going to a lot of trouble for the same long-term result.

I suspect you have had good luck with your batteries (to date) simply because you don't let them "sit" for long periods after charging...which wouldn't have mattered whether you charged to 80% or 100%. At the end of the day, I think a lot of folks need the maximum capacity/charge they can get for maximum flight time...and the fact that it isn't a good idea to run the battery pack down below 20% or so (and let it sit) is another reason I tend to charge to 100% and store around 40-60% (after flight).

 

[brett8883]

DJI uses maximum energy content from the High Volt batteries, so that they fulfil the marketing hype for staying in the air as long as possible.

Batteries can end up as the most expensive item if you abuse them. Eventually, all rechargeable batteries are doomed to become problematic, the real question is "how can I keep the probability my batteries fail at a minimum".

Correct me if I am wrong, but the three main issues are temperature, and low and high voltages.
Low voltages are not (in my humble opinion) the real issue, as DJI does forced landings before this becomes a bad habit.
High temperature is an issue, which is indicative that the batteries internal resistance is too high (heat production = I²R). Trying to fly with low amps isn't really something that can be monitored. Heat is also produced at higher voltages in the final stage of charging the battery. Bad charging is, in my opinion, the main cause.
Lastly, high voltages is something that can be controlled, and it is rather easy. It does means sacrificing energy content because you will don't reach 100%, which is really just a number DJI has predefined for you. There are many studies showing that when batteries are charged up to high voltages, the life time is significantly lowered. Studies show that the high voltages break down at least one electrode, and cause lithium dendrite formation.

proposed solution:
Use a cheap smart plug to switches off the charger in the final charge phase, before higher voltages are reached. "highly volatile batteries" are avoided.
example:
I use the "Shelly Plug S" smart plug (about €20). It measures power usage and can be set to switch off or on under certain conditions. It is controlled via their app. There are many WiFi power monitor plugs, depending on your market.
The smart plug app tells me whilst charging Mavic 2 Pro battery, the charger plug draws a maximum of 65-70 Watts power. During the last 15% the charger throttles down the amperage and power (all modern charges do this, this is standard charging procedure).
I set my smart plug to "switch off" when it is 1 minute under 62W (a few Watts under the charge starting power). I also get a message on my smart phone, so I know exactly when the charge is completed. I reach about 85% capacity with this setting.

I have been doing this for about a year with my Mavic2Pro, and on other settings with a Mini 2. I am still flying with my original batteries.

Hope this helps. It will not work on a charger that charges multiple batteries at once, because the power is shared across the batteries.
View attachment 129864

Not fully charging the battery is patently bad advice. The #1 rule is actually to always fly with a full battery because the smart battery software is reliant on a full charge to gauge the remaining power and as mentioned helps balance the cells.

Storing the batteries at full charge is an issue but they auto discharge for this very reason. Also the drone performs at its best on a fully charged battery because the higher the voltage the easier it is to supply the needed amperage. It’s much harder on the battery when the voltage is low and has to supply higher amperage.

Prolonged high temperature is a problem for storing the batteries but during use low temperature is the issue. If the battery is cold it has a harder time discharging. The batteries never get hot during the charging process unless they are hot when you start charging them or charge them in a hot environment so in practice this isn’t an issue.

Batteries are a consumable part like brake pads or air filters. If you want to extend your battery’s life the best way to do that would be to not fly as much which makes about as much sense as not fully charging them which doesn’t make sense to be clear.

On my Mavic Pro I got 450+ cycles on my three batteries before I decided to retire them and I did everything you aren’t suppose to like charging them hot, draining them down to 0% during flight, and flying faster than DJI’s firmware normally allows so I think you are really overthinking this. You don’t need to baby them to the point that you get less utility out of them. Just use them up until it’s time to replace.

 

[mdrm_mavpilot]

Not fully charging the battery is patently bad advice. The #1 rule is actually to always fly with a full battery because the smart battery software is reliant on a full charge to gauge the remaining power and as mentioned helps balance the cells.
...
On my Mavic Pro I got 450+ cycles ....

DJI Mavic 2 Pro manual states:

"Fully charge the Intelligent Flight Battery before using for the first time:
“Balanced Charging: During charging, the voltages of the battery cells are automatically balanced “

It does not say you have to charge it 100% every time to calibrate. I also thought that, that is why I have been cautious and trying this method for many months. My current status right now, after charging them with this method to around 85%:
4.16 4.15 4.15 4.15
The last time I charged them to 100% was about 35 flights ago.
I do not know how DJI balances my cells, but I have not had unbalanced cells. I have made and flown self made quads so I am aware of the basic problems. As stated in my post, I have been doing this a while to try it out. My guess is that with the Mavic2Pro smart batteries the balancing is done throughout the charging.

Traditionally chargers will balance the cells at the end of the charging cycle. I have always had a problem with that, as it always made one or more cells pop to the max and bleeding the charge out whilst charging the other "weaker" cells. This is not the way it is done with the more modern active balancing, which balances during charging. I do not really know how DJI balances, I have not had a problem though.

The Mavic Pro has 3S does not have high voltage chemistry of the current Mavic batteries. It has a much more robust chemistry and can charge at 100W (7,6A or 2C). The Mavic2Pro 4S can charge at 80W (4,5A or 1,18C); this is a considerable difference. Many pilots complain about the new batteries bloating, some flying professionaly (real estate photos & videos) go through 8 per year. I would like to meet a Mavic2Pro Pilot who got 450 flights with the newer battery chemistry.

 

[brett8883]

DJI Mavic 2 Pro manual states:

"Fully charge the Intelligent Flight Battery before using for the first time:
“Balanced Charging: During charging, the voltages of the battery cells are automatically balanced “

It does not say you have to charge it 100% every time to calibrate. I also thought that, that is why I have been cautious and trying this method for many months. My current status right now, after charging them with this method to around 85%:
4.16 4.15 4.15 4.15

It’s doesn’t say you should charge them to only 85% the rest of the time. It’s just saying it’s extra important to fully charge it the first time. In fact in the flight section of the manual it has a preflight checklist and ensuring the batteries are fully charged is the first thing on the list.


There is a manual specifically for the batteries that also addresses this.

The last time I charged them to 100% was about 35 flights ago.

Battery manual also says to fully charge and discharge the batteries every three months.

https://dl.djicdn.com/downloads/Mavic_2/20180823/Mavic_2_Intelligent_Flight_Battery_Safety_Guidelines-EN.pdf

 

[tlswift58]

DJI uses maximum energy content from the High Volt batteries, so that they fulfil the marketing hype for staying in the air as long as possible.

Batteries can end up as the most expensive item if you abuse them. Eventually, all rechargeable batteries are doomed to become problematic, the real question is "how can I keep the probability my batteries fail at a minimum".

Correct me if I am wrong, but the three main issues are temperature, and low and high voltages.
Low voltages are not (in my humble opinion) the real issue, as DJI does forced landings before this becomes a bad habit.
High temperature is an issue, which is indicative that the batteries internal resistance is too high (heat production = I²R). Trying to fly with low amps isn't really something that can be monitored. Heat is also produced at higher voltages in the final stage of charging the battery. Bad charging is, in my opinion, the main cause.
Lastly, high voltages is something that can be controlled, and it is rather easy. It does means sacrificing energy content because you will don't reach 100%, which is really just a number DJI has predefined for you. There are many studies showing that when batteries are charged up to high voltages, the life time is significantly lowered. Studies show that the high voltages break down at least one electrode, and cause lithium dendrite formation.

proposed solution:
Use a cheap smart plug to switches off the charger in the final charge phase, before higher voltages are reached. "highly volatile batteries" are avoided.
example:
I use the "Shelly Plug S" smart plug (about €20). It measures power usage and can be set to switch off or on under certain conditions. It is controlled via their app. There are many WiFi power monitor plugs, depending on your market.
The smart plug app tells me whilst charging Mavic 2 Pro battery, the charger plug draws a maximum of 65-70 Watts power. During the last 15% the charger throttles down the amperage and power (all modern charges do this, this is standard charging procedure).
I set my smart plug to "switch off" when it is 1 minute under 62W (a few Watts under the charge starting power). I also get a message on my smart phone, so I know exactly when the charge is completed. I reach about 85% capacity with this setting.

I have been doing this for about a year with my Mavic2Pro, and on other settings with a Mini 2. I am still flying with my original batteries.

Hope this helps. It will not work on a charger that charges multiple batteries at once, because the power is shared across the batteries.
View attachment 129864

I still fly my Air2 with the same 3 batteries it came with a year ago and no issues yet. Think you found a solution for a problem that does not exist.

Many others have commented as well.

Also, most of these things - like batteries and such have many previous posts - that a simple search would uncover with the same answers. BTW - I do see you are fairly new; but the "SEARCH" feature is quite a time saver when looking for answers and also keeps the "feed" from having the Top 20 Most Asked Questions - asked on a consistent basis (daily / weekly).

 

[sharkface]

most charging blocks only recharge one battery at a time. it picks the battery with the most juice . this is so you can get back in the air faster.
I think batteries recharge faster when closer to being full.