Swollen Battery – What causes it - How to Prevent

[bobec231]

There is a lot of discussion on batteries so this post is to shed some light on the issue
Let’s understand how a battery pack is made and works.
The Lithium Polymer (LiPO) battery pack consists of a circuit board and 3 individual 3.7v batteries, a multi-pin connector and a housing.
The circuit board provides individual monitoring and control for charging and discharging of each battery cells.
Each cell is made of a flexible plastic outer housing, an anode (+ terminal), a cathode (- terminal) and electrolyte. During the process of discharging and charging, charged ions flow through the electrolyte.
Over time EVERY battery will experience electrolyte breakdown/decomposition as the electrolyte material degrades. During this breakdown process lithium and oxygen is produced to form lithium oxide on either the anode or cathode. Excess oxygen and other gases are given off and this is what causes the bulge in the battery. Pure Oxygen is what burns (Remember Apolo 1).

How to fix a swollen battery: YOU Can’t as there is no place for the gas to go.
Some people squeeze the battery which will push the gas toward the ends of the battery.
This can be done but will pose a risk.
How to prevent the battery from swelling.
DO NOT drain battery below 3.2v per cell or 9.6v for an 11.4v battery pack
DO NOT overcharge the battery.
DO NOT keep batteries fully charged
Simple rule of thumb keep your batteries at 80% when not in use.
Charge battery the morning you plan to fly.
If you have several batteries look at getting a charging system that will charge several batteries at one time. Then put the AC input to that charger on a timer that will turn it on at a time such that all the batteries will be 100% charged just prior to you heading out to fly.
DO NOT recharge a warm battery.
DO NOT store batteries in hot cars or trunks of cars.
DO NOT allow battery to freeze. If frozen allow to warm slowly.
DO NOT charge a swollen battery in any environment that will sustain fire in the event that the battery burns. Batteries don’t tend to explode, they just burn.
HEAT is a battery’s worst enemy.
If you take care of your battery it should provide at least 200 full charge cycles and if your lucky 300+ but capacity will begin to drop after about 100 full cycle charges.

 

[DanMan32]

Bad production can also cause LiPo/Lion batteries to prematurely swell or degrade. Just go through claims of M2 batteries swelling. Most were produced 7-8/2018. I'm sure in many cases the trigger was heat, such as keeping in a car but still the odds are imbalanced.

Your 11v assumes a 3S pack. Many DJI batteries are 4S.

 

[Redleg]

Good insight into LiPO. Also, and this is me nitpicking, oxygen isn’t flammable. It’s an oxidizer (one side of the fire triangle) and the more that’s present, the more rapidly the fuel will combust. Apollo 1 is a great (albeit tragic) example of the extremely accelerated rate of combustion caused by a 100% oxygen environment.

I’m a huge Apollo Program nerd. ?

 

[DanMan32]

I also meant to make that point.

 

[KennyL]

There is a lot of discussion on batteries so this post is to shed some light on the issue
Let’s understand how a battery pack is made and works.
The Lithium Polymer (LiPO) battery pack consists of a circuit board and 3 individual 3.7v batteries, a multi-pin connector and a housing.
The circuit board provides individual monitoring and control for charging and discharging of each battery cells.
Each cell is made of a flexible plastic outer housing, an anode (+ terminal), a cathode (- terminal) and electrolyte. During the process of discharging and charging, charged ions flow through the electrolyte.
Over time EVERY battery will experience electrolyte breakdown/decomposition as the electrolyte material degrades. During this breakdown process lithium and oxygen is produced to form lithium oxide on either the anode or cathode. Excess oxygen and other gases are given off and this is what causes the bulge in the battery. Pure Oxygen is what burns (Remember Apolo 1).

How to fix a swollen battery: YOU Can’t as there is no place for the gas to go.
Some people squeeze the battery which will push the gas toward the ends of the battery.
This can be done but will pose a risk.
How to prevent the battery from swelling.
DO NOT drain battery below 3.2v per cell or 9.6v for an 11.4v battery pack
DO NOT overcharge the battery.
DO NOT keep batteries fully charged
Simple rule of thumb keep your batteries at 80% when not in use.
Charge battery the morning you plan to fly.
If you have several batteries look at getting a charging system that will charge several batteries at one time. Then put the AC input to that charger on a timer that will turn it on at a time such that all the batteries will be 100% charged just prior to you heading out to fly.
DO NOT recharge a warm battery.
DO NOT store batteries in hot cars or trunks of cars.
DO NOT allow battery to freeze. If frozen allow to warm slowly.
DO NOT charge a swollen battery in any environment that will sustain fire in the event that the battery burns. Batteries don’t tend to explode, they just burn.
HEAT is a battery’s worst enemy.
If you take care of your battery it should provide at least 200 full charge cycles and if your lucky 300+ but capacity will begin to drop after about 100 full cycle charges.

OUTSTANDING POST !!!!!
Thank you

 

[Smokieflies]

Thanks for sharing, very informational.

 

[RickinWaST]

Thanks for this!

 

[Tankertel]

There is a lot of discussion on batteries so this post is to shed some light on the issue
Let’s understand how a battery pack is made and works.
The Lithium Polymer (LiPO) battery pack consists of a circuit board and 3 individual 3.7v batteries, a multi-pin connector and a housing.
The circuit board provides individual monitoring and control for charging and discharging of each battery cells.
Each cell is made of a flexible plastic outer housing, an anode (+ terminal), a cathode (- terminal) and electrolyte. During the process of discharging and charging, charged ions flow through the electrolyte.
Over time EVERY battery will experience electrolyte breakdown/decomposition as the electrolyte material degrades. During this breakdown process lithium and oxygen is produced to form lithium oxide on either the anode or cathode. Excess oxygen and other gases are given off and this is what causes the bulge in the battery. Pure Oxygen is what burns (Remember Apolo 1).

How to fix a swollen battery: YOU Can’t as there is no place for the gas to go.
Some people squeeze the battery which will push the gas toward the ends of the battery.
This can be done but will pose a risk.
How to prevent the battery from swelling.
DO NOT drain battery below 3.2v per cell or 9.6v for an 11.4v battery pack
DO NOT overcharge the battery.
DO NOT keep batteries fully charged
Simple rule of thumb keep your batteries at 80% when not in use.
Charge battery the morning you plan to fly.
If you have several batteries look at getting a charging system that will charge several batteries at one time. Then put the AC input to that charger on a timer that will turn it on at a time such that all the batteries will be 100% charged just prior to you heading out to fly.
DO NOT recharge a warm battery.
DO NOT store batteries in hot cars or trunks of cars.
DO NOT allow battery to freeze. If frozen allow to warm slowly.
DO NOT charge a swollen battery in any environment that will sustain fire in the event that the battery burns. Batteries don’t tend to explode, they just burn.
HEAT is a battery’s worst enemy.
If you take care of your battery it should provide at least 200 full charge cycles and if your lucky 300+ but capacity will begin to drop after about 100 full cycle charges.

As a flyer of fixed-wing and rotor-wing aircraft for many years using Lipo's, I have had some great issues with them, your explanation is very Idiot proof and correct. Good post.

 

[Maisimba]

Thank you for the information.
What is the proper time that we should activate automatic discharging for fully charged batterries when they 're not in use?

 

[Paci Fista]

Currently in tropical hot and humid climate (30 C, 70+% RH). Does it help to vacuum-bag my dji batteries and store them in the fridge?

 

[nafisgal]

Thank you for the information.
What is the proper time that we should activate automatic discharging for fully charged batterries when they 're not in use?

Dji go 4 comes with five preset days before the battery discharge occurs.
Personally, I have the download scheduled in three days, if I don't fly ... I like to take care of my batteries ... especially now in winter ..

 

[Dolan Ellis]

Thank you much. Very informative. Living in Arizona, I am very familiar with power tool batts swelling from direct sun and heat in the garage. For this reason I do not fly on extremely hot days of summer. Instead, I fly in the coolness of our mountains.

 

[DanMan32]

Dji go 4 comes with five preset days before the battery discharge occurs.
Personally, I have the download scheduled in three days, if I don't fly ... I like to take care of my batteries ... especially now in winter ..

Actually up until the last month, default was 10 days on all their products.

 

[AntDX316]

3.8V is actual storage voltage per cell.
Charging batteries while they are hot w/o a Smart charger is bad.
Using batteries to full potential when they are cold w/o regulation is bad.
Leaving batteries at 4.2-4.4V+ per cell forever is bad.
Letting a cell drop below 3.2V and resurrecting and using it is bad.

 

[DanMan32]

Fortunately DJI smart batteries won't let you charge them when hot.
Won't let you charge again if already full.

I wish the Tello battery at least had a charge indicator.

 

[onahi2002]

Is it best to Charge the battery to approx 80% for storage ? (currently 19%)

 

[GadgetGuy]

3.8V is actual storage voltage per cell.
Charging batteries while they are hot w/o a Smart charger is bad.
Using batteries to full potential when they are cold w/o regulation is bad.
Leaving batteries at 4.2-4.4V+ per cell forever is bad.
Letting a cell drop below 3.2V and resurrecting and using it is bad.

On the M2 batteries, 0% remaining battery is still well above 3.5V per cell, with almost 2 minutes of full power left after 0%, before dropping below 3.0V on any cell, which forces an uncancellable descent, but with full lateral control, before it runs into the ground!

 

[AntDX316]

On the M2 batteries, 0% remaining battery is still well above 3.5V per cell, with almost 2 minutes of full power left after 0%, before dropping below 3.0V on any cell, which forces an uncancellable descent, but with full lateral control, before it runs into the ground!

Inspire 1 was showing 3.4V per cell at 30%.. but that was under sag. If you are checking 0% remaining while it's on the ground w/ the motors off, that doesn't count. When I landed the voltages went up to 3.8V or something.

 

[GadgetGuy]

Inspire 1 was showing 3.4V per cell at 30%.. but that was under sag. If you are checking 0% remaining while it's on the ground w/ the motors off, that doesn't count. When I landed the voltages went up to 3.8V or something.

On the Mavic 2, the 3.5V per cell is in the air at 0% remaining battery, flying at full speed in P mode. The M2 has a very conservative battery display for 0%. You have an additional 2 more minutes of flight left, after 0% is displayed, which is how long it takes to drop to below 3.0V.