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UPDATE-Swollen Battery – What causes it - How to Prevent
As a result of comments from a previous post and not being able to update a specific post the following is provided to help further understand LiPO batteries.
There are 3 values you need to know 3.2v – 3.7v – 4.2v
All battery packs are made up of multiple cells, each cell is a stand alone battery that is charged and monitored on its own. All cells are then series together to power the device. Thus if your battery is rated at 11.1 volts [3s] it contains 3 separate batteries referred to as cells.
Drone manufactures correlate voltages under load to initiate certain safety features like return to home or simply land now. These values are programmed based on a good battery with known discharge characteristics. As a battery ages these change such that a new battery may read cells with 3.1v and still be able to fly and additional 2 min and make it home while a single bad or weak cell may simply stop working and the drone will loose control and fly down and away.
NOTE THESE ARE NO LOAD VALUES.
3.2 Volts
3.7 Volts
4.2 Volts
Storage – If you live in a geographical location where it is very hot, storage in a refrigerator, is a good practice, in fact whatever the environment storage in a refrigerator is good. However it is recommended to place battery in a plastic bag and store it, at the bottom of the refrigerator, in the vegetable bins.
Fast chargers – Using a fact charger on a depleted battery to bring the battery/cells to 100 percent or 4.2 volts per cell will create a lot of heat inside the battery. That heat will cause the battery to degrade much quicker and result in swelling sooner. Swelling is typically a cumulative activity it does not happen during a single charge/discharge. If it does swell a lot, that battery may burst into flames. Using a fast charger to bring 3.7 volt cool battery to 4.2 volts is safe to do. Using a quick charger to bring a depleted cool battery to 3.7 volts is also safe to do.
Many automatic charging systems monitor the temperature and reduce charging current based on battery surface temp. Most battery packs will have 1 temperature sensor for multiple cells which will allow a weak or failing cell to have to heat the whole battery pack to achieve reduced charging currents.
Conservatively managing how you charge and discharge will provide a battery that could last the life of your drone. I have a fast charger for multiple battery packs that I operate on a programmable timer connected to my phone. Based on experience I know I can achieve approx. 3.7v in 47 min. So I charge for that time and then turn off. If I am going to fly the next day I have a different time program that will turn on the charger several hours prior to leaving so all my batteries are good to go when needed.
PREVIOUS POST BELOW
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 electrolite 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 facilates burning (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 result of comments from a previous post and not being able to update a specific post the following is provided to help further understand LiPO batteries.
There are 3 values you need to know 3.2v – 3.7v – 4.2v
All battery packs are made up of multiple cells, each cell is a stand alone battery that is charged and monitored on its own. All cells are then series together to power the device. Thus if your battery is rated at 11.1 volts [3s] it contains 3 separate batteries referred to as cells.
Drone manufactures correlate voltages under load to initiate certain safety features like return to home or simply land now. These values are programmed based on a good battery with known discharge characteristics. As a battery ages these change such that a new battery may read cells with 3.1v and still be able to fly and additional 2 min and make it home while a single bad or weak cell may simply stop working and the drone will loose control and fly down and away.
NOTE THESE ARE NO LOAD VALUES.
3.2 Volts
Is the point where your battery/cell is discharged.
Battery/cell should not be discharged this low very often as it will shorten its life
Most battery manufacturers have circuitry that will cut off the battery at 3.0 volts
3.7 Volts
This is the design voltage/rating
When using the battery on a regular basis this is the voltage you want to keep the battery/cell in a semi stand-by mode.
Long term storage battery/cell should be discharged to or slightly below this value
4.2 Volts
This is the upper voltage that a battery/cell can be charged to.
Some fast chargers will charge to as high as 4.4 volts...NOT GOOD
By design it an acceptable charge voltage and represents 100 percent or fully charged
Keeping a battery at this voltage for long periods of time will shorten the batteries life and will lead to swelling sooner.
Storage – If you live in a geographical location where it is very hot, storage in a refrigerator, is a good practice, in fact whatever the environment storage in a refrigerator is good. However it is recommended to place battery in a plastic bag and store it, at the bottom of the refrigerator, in the vegetable bins.
Fast chargers – Using a fact charger on a depleted battery to bring the battery/cells to 100 percent or 4.2 volts per cell will create a lot of heat inside the battery. That heat will cause the battery to degrade much quicker and result in swelling sooner. Swelling is typically a cumulative activity it does not happen during a single charge/discharge. If it does swell a lot, that battery may burst into flames. Using a fast charger to bring 3.7 volt cool battery to 4.2 volts is safe to do. Using a quick charger to bring a depleted cool battery to 3.7 volts is also safe to do.
Many automatic charging systems monitor the temperature and reduce charging current based on battery surface temp. Most battery packs will have 1 temperature sensor for multiple cells which will allow a weak or failing cell to have to heat the whole battery pack to achieve reduced charging currents.
Conservatively managing how you charge and discharge will provide a battery that could last the life of your drone. I have a fast charger for multiple battery packs that I operate on a programmable timer connected to my phone. Based on experience I know I can achieve approx. 3.7v in 47 min. So I charge for that time and then turn off. If I am going to fly the next day I have a different time program that will turn on the charger several hours prior to leaving so all my batteries are good to go when needed.
PREVIOUS POST BELOW
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 electrolite 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 facilates burning (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.
