Any Reason to Buy Fireproof Bag for Mavic Pro Batteries?

[Cheech Wizard]

No, no need. I've been using Lipos in R/C for over a decade. I used to race electric R/C cars and travelled a lot in the Western States. In all that time and hundreds of races, I've only witnessed 2 lipo fires. Both due to user error in charging... The vast/overwhelming time lipos have issues is during charging. Next and to a lesser extend, during use or discharge. I've never seen or heard of a lipo that was in a steady state, erupt into flames. Personally, I had a large capacity lipo that I left in my R/C tool box fully charged for over 2 years. When I found it, it was so swollen the plastic case was split, and I couldn't even squeeze it back together. From that day forward I am/was more careful with my Lipos...

DJI does a very good job with their smart batteries. I've never personally seen or heard of a DJI battery that was properly cared for and an OEM charger used that had issues. Last year I traveled a lot with my MP and my Spark and never had an issue going through TSA. I was never asked by anyone to see or inspect my drone and/or batteries.

I trust my DJI batteries to just keep them in the various GPC cases I have. But for my Lipos for my racing drones. When I don't use those for long periods they go in an Ammo can and stored in a cool dry place away from anything flammable...

You said " I've only witnessed 2 lipo fires" WTF? Thats 2 more than I want to see.

 

[Cheech Wizard]

The bag rule I'm sure was intended for loose lipos, not ones like the DJI's. Otherwise laptops and phones would need bags. However it may be an issue to convince security.

Phones and Vape Pens too.

Happens all the time in Asia. If you need more go here:phone catches fire in pocket - YouTube

 

[gnirtS]

Happens all the time in Asia - mainly due to counterfeit batteries and chargers.

 

[MavicMo]

It happens, that a fact. I hate hearing about plane crashes, but it happens. I’ve probably been around thousands of lipos being charged and discharged. 2 fires represent less than 1%. A lipo bag would have done ZERO. Proper handling of those batteries could have prevented the fire.

Lipo bags don’t stop or prevent fires or make some one smart....

You said " I've only witnessed 2 lipo fires" WTF? Thats 2 more than I want to see.

 

[Cheech Wizard]

It happens, that a fact. I hate hearing about plane crashes, but it happens. I’ve probably been around thousands of lipos being charged and discharged. 2 fires represent less than 1%. A lipo bag would have done ZERO. Proper handling of those batteries could have prevented the fire.

Lipo bags don’t stop or prevent fires or make some one smart....

Battery bags do work it seems. Not sure where your going with a bag "Making someone smart".

Obviously the 2 fires you saw were without a bag and you are just assuming the bag wouldn't help. So, you have ZERO proof that a bag wouldn't have helped.

 

[Worsedog]

I realize this thread is a year old, but still thought I could add to it.

I can't speak to the effectiveness of the bags, but the Mavic battery catching fire is not a pretty sight. I had three OE batteries that I don't feel I abused start to show signs of swelling. The label side was inflated and made it difficult to install the batteries. Being the genius, I thought maybe the label cover was containing warm air, so what do you do, let the air out?!

Well, don't try that! It seems that the label is printed directly on the outside of the cell itself. The little tiny hole I poked in it started the chain reaction fire that consumed all three cells in the battery. Unfortunately my phone was in the house, so no awesome fiery video. Suffice it to say it was quite spectacular and very warm.

So now I have placed an order for some replacements.

 

[DanMan32]

Assuming your poke didn't cause a short, they're probably sealed the way they are to prevent exposure to moisture. I seem to recall exposure to moisture could cause combustion. I thought they could install a one way valve but perhaps the risk of moisture infiltration is too great.

 

[Worsedog]

Obviously my poke did create a short, as it didn't catch fire until I poked it. I was mainly wanting to let others learn from my error. I was surprised that the incredibly shallow puncture was enough to start the fire. Fortunately I was in the garage and able to pitch it into the driveway to burn out. Although it is fairly known that water is not an extinguishing agent for a lithium fire, that might still be the impulse reaction indoors. While I wouldn't make a huge deal of it, perhaps another barrier between the actual cell and the environment would be wise.

 

[DanMan32]

I did some reading. Apparently water, though not the first choice, is OK for a lion lipo fire. There's not enough lithium in it to cause a problem. Extremely low humidity is required for manufacturing though.

It's possible to puncture the plastic wrapping and not cause a short which is what I was curious if you managed to accomplish.

As for battery bloat, I did find scientific details about it when caused by deep discharge. Part of the problem is that copper inside starts to dissolve and when you charge it copper starts depositing in the wrong places and eventually causing a short.
It mentions most causes of bloating, which includes manufacturing faults, excess heat, but only focuses details on the excess discharge cause.

Battery Reliability and Test | Ansys Reliability Engineering Services

Ansys battery design experts understand the chemistry and failure modes in batteries and evaluate which battery technology is ideal for your product.

www.dfrsolutions.com

DJI should really consider recalling batteries that they seem to know but won't admit have manufacturing faults. How do we know that they know? Because after over 4 years of default self discharge days being 10 days, even making it unchangeable with the M2, they now decide to not only make it changable, but now sets the default to 5 days. By the way, was the default only changed for the M2? If so, that's more implied evidence that they know they have defective M2 batteries among us.

 

[MAvic_South_Oz]

I did some reading. Apparently water, though not the first choice, is OK for a lion lipo fire. There's not enough lithium in it to cause a problem. Extremely low humidity is required for manufacturing though.

Probably the best Lipo incident doc I have found . . . PDF download link you can save for future reading.

Lithium batteries: safe to fly? | Safety First

Today, Lithium batteries play a barely visible, yet essential role in both our daily life and aviation alike. Manufactured and handled correctly, Lithium batteries are safe. But production failures, mishandling, or not being aware of their specific characteristics can have serious repercussions.

safetyfirst.airbus.com

Reading further on this recently, I found Halon has been banned for use in extinguishers in a lot of countries now, BCF seems to be a common Halon mix extinguisher.
Halon replacement seems to be recommended as HFC type extinguisher (thanks Google), as per another aircraft page found . . .

Halon Fire Extinguishers | SKYbrary Aviation Safety

Halon fire extinguishers are the most effective universal equipment for dealing with aircraft fires. However, health and environmental concerns have lead to the search of alternatives.

www.skybrary.aero

 

[Worsedog]

Dan. As all three batteries that I had were swollen, curiosity got the better of me and I tried unsuccessfully to deflate them. I wish I had my phone with me, it would have made an awesome YouTube video.

Also, thanks for the link about deep discharge, that is an interesting site. I'm not sure, but I don't think that I would have considered my flying habits deep discharge. I never flew to the point that it stopped functioning. When I got the low battery warning, which is set at the factory default, I usually returned right away. Only once or twice did I fly until it would return automatically due to battery levels. Even then they were not totally discharged.

As a side note, I bought four OEM batteries from Amazon that arrived yesterday and I am returning two as they would not take a charge at all. Just some strange light blinking that did not correspond with any of the error codes.

 

[DanMan32]

I found that article focused too much on issues/swelling due to deep discharge. It's hard to say if the same conditions/danger of internal short circuit would occur if the battery swelled for the other reasons.
Swelling due to long term effect of factory defect would be hard to determine though.