DJI Batteries and Cold Weather . . .

[Droniedon]

I flew my ma2 today for a couple hours in 3° F with now issues. I'm sure a person could activate a hand warmer and tape it over battery.

 

[TTP]

How come ... I mean, how can flying with a SC mitigate possible problems with the drone battery?

I meant that SC does much better in the cold than many RC with mobile phones.

 

[Mid-AtlanticDroneServices]

I’ve been lurking on this thread for quite some time and reading the debate about cycling, storage mode, etc. I appreciate all the technical information as it explains a lot of my real world experiences. My dad flies model aircraft and has been using lithium polymer batteries for sometime. He has personally had them swell and even go on fire because they weren’t properly stored. A basic knowledge of the differences in Lipo and lithium ion batteries essential. It’s why I don’t have to do anything to my electric yard tools. They use lithium ion batteries that don’t have to be cycled and seem to hold a charge virtually forever.

In my experience with lipos, I simply use common sense. Don’t over discharge the battery, use storage mode as appropriate and keep an eye on cycle count and voltage from time to time. Obviously try to avoid extreme temperatures. In other words, if you don’t play stupid games, you won’t win stupid prizes!

 

[BigAl07]

I’ve been lurking on this thread for quite some time and reading the debate about cycling, storage mode, etc. I appreciate all the technical information as it explains a lot of my real world experiences. My dad flies model aircraft and has been using lithium polymer batteries for sometime. He has personally had them swell and even go on fire because they weren’t properly stored. A basic knowledge of the differences in Lipo and lithium ion batteries essential. It’s why I don’t have to do anything to my electric yard tools. They use lithium ion batteries that don’t have to be cycled and seem to hold a charge virtually forever.

In my experience with lipos, I simply use common sense. Don’t over discharge the battery, use storage mode as appropriate and keep an eye on cycle count and voltage from time to time. Obviously try to avoid extreme temperatures. In other words, if you don’t play stupid games, you won’t win stupid prizes!

I think you may have your terms backwards or have a misunderstanding of the differences.

LiPo is actually more stable in terms of physical properties but is more expensive. Li-Ion use liquid electrolyte that is much more susceptible to damage which is more likely to have a thermal runaway. Li-Po use a solid or "gel" type electrolyte which is much more stable especially in terms of abuse or a crash situation.

• Li-Ion cheaper and more energy per mass but less stable
• Li-Po more expensive to produce but more stable with less life-span over all

 

[Mid-AtlanticDroneServices]

I think you may have your terms backwards or have a misunderstanding of the differences.

LiPo is actually more stable in terms of physical properties but is more expensive. Li-Ion use liquid electrolyte that is much more susceptible to damage which is more likely to have a thermal runaway. Li-Po use a solid or "gel" type electrolyte which is much more stable especially in terms of abuse or a crash situation.

• Li-Ion cheaper and more energy per mass but less stable
• Li-Po more expensive to produce but more stable with less life-span over all

Thanks. I appreciate that information. I was really just talking about the real world applications.

 

[imnotmarvin]

If you're not flying regularly, what's the best practice for storing the batteries? The original post says not to store them charged for more than 24-48 hours but to also not run them below 20%. If I charged them in the morning for an afternoon flight that doesn't happen and my drone is going to be sitting for a couple weeks, what should I do with the batteries?

 

[Ralph thompson]

Use the USB adapter and plug in yr phone/tablet/watch/bike light etc until u get to 2 of 4 green lights. Don’t forget to turn on the battery

 

[StoonHooper]

I enjoyed reading the opening article from Ken Booth on this thread. Excellent info thank you, and I think it sets a good foundation for new-comers like my self as to the characteristics and performance of the batteries. Living in the Seattle area I’ve already experienced the changes in my batteries performance because of the rapid and varied temperature changes.

But the chart data is an excellent reference to consider when I look at ‘todays temperature’ to get a good sense of what to expect from my batteries for the days flight.

I have yet to fully understand the “intelligent batteries” and how that plays into the charging scenarios and the flight times. But up here in the Northwest the weather changes rapidly and I have already seen how that impacts my flight times based on power consumption.

 

[EpicFlight]

As I've said elsewhere, you really have very little control over managing DJI lipos to preserve and protect them. There is a highly functional, and limiting, BMS in between you and the underlying lipos.

Here's what you can do with a DJI battery:

• You can request charging by attaching a suitable charger. That's all you can do in terms of charging... The BMS will decide if it needs to charge, and if conditions (battery temp, state of charge, cell balance, supply voltage, etc.) are suitable.
• You can stop charging by removing the battery from the charger, but only if the BMS is still charging the battery.
• You can discharge the battery by flying it, or using a discharge feature on a charging device.

That's it. You have absolutely no control over any meaningful parameter w.r.t. lipo maintenance, health, longevity, or safety. DJI has really locked you out.

The ONLY factor you have any control, and therefore a role, is ensuring the batteries aren't stored depleted. A battery can't charge itself

IMO, you need do nothing more than make sure your bats have at least a 50-60% charge when you put it away after flying. Easiest way to do this is fully charge after every outing, then let the self-discharge storage feature take care of it if you don't use them again for a few weeks.

Have DJI packs failed? Swelled? Yes. Since there's no behavior on the part of the owner that can cause this, the cause is a defect.

 

[mikegrad]

great thread. I use this year round, plugs into the back of the car, and you can pre-warm or pre-cool it inside before heading out.

https://www.amazon.com/Koolatron-P75-36-Quart-Electric-Cooler/dp/B0001MQ7E0/ref=sr_1_11?crid=3PVFGAVYOGJPV&keywords=electric+cooler&qid=1648425293&sprefix=electric+cooler%2Caps%2C69&sr=8-11

 

[MAvic_South_Oz]

I just want to say, I love Australia sooo much

 

[RealSting]

My battery maintenance:

After every flight I charge my batteries to the 3rd green light flashing but checking it’s below or around 62%.

Then (my drone is new so will be doing this) after 20 or so cycles, discharge/fly batteries to below 20%, then recharge them back to 3rd light flashing when not in use. This outlines what’s in the manual for normal use - I don’t fly in extreme temperatures.

If I’m not going to be using the drone for extended periods (months at a time), I would fully charged the batteries every two weeks and discharge them to around 20% before returning them to the battery storage charge as mentioned above. This too, is in the DJI manual.

I did exactly the same for my P4 which I used very infrequently (many months of not using it), and the batteries never let me down. I used the P4 battery hub in ‘storage mode’ which brought the batteries to the ‘3rd light flashing’ - which is why I use the same ‘third light flashing’ status for my A2S.

The batteries are stored in the drone case in a dry room that ranges from 25°C down to around 10°C throughout the year. Away from direct sunlight and radiators.

I monitor my rooms humidity and temperature (as it’s also my office) with a cheap Bluetooth device which gives me piece of mind.

To be honest I wouldn’t want or perhaps be able to do more than this, I’m busy, my mind is on life and not looking after LiPo’s, and I’m sure the manufacturers know this!

 

[RealSting]

I just want to say, I love Australia sooo much

I like Kangaroos !

 

[test2000Anafi]

Some of you may know Ken Booth who was originally active with DJI and very involved in their Battery Design. :

(the below is 100% from Ken Booth)
"First please look at the attached image, this should really explain all you need to know on how cold effects capacity. Once you understand this, most of the other pieces come together.

Now that we understand what cold does to capacity let us talk about overall discharge.

Most of us know that C is based on overall capacity, so if your capacity goes down, so will your C rating. Unfortunately, DJI does not use batteries that have much overhead, this is mostly due to keep the weight down at a certain price point. So, when we start to pull from this cold battery a few things can happen. If the pack has not been preheated, it will start to preheat itself. You are probably asking; well if that’s the case, why do I have to worry about preheating?

Well, if the battery is too cold and C rating has been affected, it will not be able to supply enough output (required C), going over its current C rating due to loss of capacity. This starts heating the pack up rapidly. Which in turn makes the pack quickly go past normal operating temperatures, which will also decrease output. This will cause immediate damage and more than likely a cell failure under extreme conditions. This is called thermal runaway.

The next thing that can happen is part of the smart logic and safety features of these packs. Since the cold does affect overall capacity, this could kick the overcharge protection in and start a self-discharge of the pack(s). In theory this is good and prevents possible damage or even a fire but can also play with the SOC (state of charge) that calculates the current charge state. While the logic is pretty darn good its not perfect. The percentage could be off as much as 20-30%. The same goes for an automatic timed self-discharge, you NEVER want to fly a pack that has been allowed to self-discharge. I would also highly advise to never fly ANY partially discharged pack unless that pack has been used that same day.

So, what can we do to help or minimize these issues?

Preheat packs in cooler weather. I would say anything below 55F you should start paying attention. One easy way to keep packs nice and warm in colder weather is dry rice and an ice chest / bag. Take a few pounds of dry rice (this depends on how big of a cooler you have) and place the rice in a large zip-lock bag(s). Microwave the rice for about 5-10mins or until very hot. Place the rice in the cooler. This should keep packs warm for most of the day. I prefer this method since the rice is reusable and does help with small amounts of moisture as well.

DO NOT Keep full pack charged for more than 24, 48 hours MAX! Any type of lipo does not like to be kept fully charge for a long period. This is not just for smart packs, any lipo will degrade over time if kept in a full charge state. Signs of this can be shorter flight times and possibly puffing (gassing) in extreme cases.

DO NOT over discharge your packs. Anything past 20%, consider it a reserve. If you commonly go past this 20% mark you will shorten you packs life. This is extremely important during extreme temps, both hot and cold weather.

DO NOT expect the same performance. In cold weather, even after preheating. Some craft keep packs warmer than others. Be easy on the packs, especially at the start of the flight, even after preheating.

Stop and hover. This is important for ANY time of year and should be included in you SOP. When you first take off, stop and hover for at least a minute. Even prior to a mapping run, take off and hover for a minute before the start of a mission. It is worth that 1 or 2mins less of mission time. Check all controls and watch the behavior of the craft. If you start to see drifting or any odd behavior, that is your clue to land and diagnose the issues. You would be surprised at how many logs of failures I have seen and the first thing the operator does is a punch out. This is probably the worst thing you can do with these types of craft. When these craft are not well, they usually show signs at the begging of flight. I simple hover with some minor control inputs can do wonders at showing a healthy or sick craft. This also allows the internals of the craft and packs to start warming up properly.

Check voltages and balances in the app and not percentages. Always have voltage options turned on. This is something to check when you are doing the hover and control test at the start of flight. Open the battery menu and check each cell, make sure everything looks good. Make sure you do not see any cells dropping rapidly and or voltage issues.

Voltages. A freshly charged pack should be around 4.2-4.3v per cell. A clue to a bad SOC is a percentage showing 99-100% but a much lower voltage. Once again, during that initial hover period check the cell voltages or overall voltage. If you see something like 3.9v at 99-100% charge, that pack either has a SOC issue or the pack is not healthy. If you do see any anomalies, do not risk it! Land and swap the packs.

Maintenance. With smart packs there’s only a few basic maintenance items you must be aware of. For older packs such as the p4 pack I would still recommend bringing these packs down below 10% every 20-30 flight or after long periods of storage. When you go past 20% make sure you are not flying hard and only hovering at a low altitude. The key here is to drain the pack as slow and gently as possible. What this does is perform something like a soft reset (calibration) on the SOC counter. Now if you are constantly using packs and not abusing them, you more than likely do not have to worry about a calibration. But remember long period of storage might require this to get the battery back to calculating accurately. After long storage periods its always best practice to monitor the pack during the initial flight. I know I am **** but if a pack has sat more than 3 months, I fully charge and then hover for the entire flight down to 20%. During this flight I am constantly monitoring the packs performance via the battery window. If the pack is not well this will usually show signs, especially voltages and balance issues.

Newer packs such as the m2 and enterprise models should not require this and most issues we see are due to storage charge and temperatures. With that being said, there are times a good battery calibration can bring back unhealthy packs in these new generation smart batteries.

I know I have probably missed some stuff, but it is simple. Keep packs above 60F in cold weather, not push them hard, do not keep batteries fully charged for long periods of time and do not store while fully charged in cold conditions.

I know for first responders, a lot of this is hard to do but you must develop a battery maintenance schedule. Batteries still need to be cycled. I would suggest at least twice a week down to 50% if kept at full levels.

One more thing, please know that warm weather works in a very similar way. You do not want packs starting off too warm. Try to keep packs below 90F prior to flight. Also, the same with storage, never store fully charged packs in extreme temperatures.

I have tried my best to not get too technical and put it laymen terms as best as I could."
(all credit goes to Ken Booth)

View attachment 123882

I already did nearly all of it, except for the rice thing. Only once did I land below 20% in over 400 flights. My 3 batteries were all 88-92% health still. Great advice thus!!

 

[test2000Anafi]

Also for my anafi 10-15 minute flight per battery were my SOP, so it would be 3 missions at around that time each, so that i could immediately store the batteries if needed. It will be the same for my mini 3 pro