BU-808A: How to wake up a dormant Li-ion battery?
BU-808A: How to wake up a dormant Li-ion battery?
Subject:
This article provides information on why batteries can go to sleep and how to restore them to service.
Dormant battery
Li-ion batteries contain in their structure protective circuit which prevents them from being damaged in the event of over-discharge. This important element disconnects the link making it theoretically useless. After an extended period of time, the battery may go into sleep mode due to self-discharge, which is partly caused by the cell's chemical processes and partly by the battery protection circuitry constantly consuming a small current. Depending on the manufacturer, the protection circuit is activated at a voltage from 2.2V / cell to 2.9V / cell. (See also BU-802b: Elevated Self-discharge )
Waking up from sleep
There are chargers that can wake a dormant battery by increasing its voltage in order to deactivate the protection system (boost). Chargers without this option detect the battery as damaged and will not charge the dormant battery. Wake-up is based on applying voltage to the battery contacts while limiting the current to a small level. In this way, the protection circuit receives power and the battery voltage can rise above the threshold above which normal charging begins. Typically the reviving process takes about a minute. If the cell voltage does not rise to the expected level then the cell should be considered damaged. Figure 1 shows in a simplified way what the wake-up procedure is.
Figure 1. Waking up a Li-ion battery from sleep mode.
Risk
Do not use this method on batteries whose voltage has fallen below 1.5V / cell and has remained at this level for a week or more. Copper bridges inside the cell can lead to a partial or complete short circuit. Charging such a battery can cause process instability, excessive heat generation, including the risk of fire. Advanced chargers can recognize such situations and stop the process of reviving a dormant cell.
Waking up the cell carries one more risk - polarity reversal. Most chargers can recognize a cell connected inversely, as long as there is voltage on its terminals. The dormant battery does not show any voltage at the terminals, so be very careful as there is a risk of connecting the battery upside down. In the absence of voltage, the charger may try to wake up the battery, but if the polarity is reversed, the cell will be permanently damaged. Li-ion cells are much more sensitive to polarity reversal than other types of batteries.
Sleep prevention
Storing lithium-ion batteries is not an easy topic at all. On the one hand, manufacturers recommend maintaining a state of charge in the range of 40% - 50% of the nominal value, but on the other hand, self-discharge of cells, especially at elevated temperatures, may cause excessive discharge and entering the sleep state. Knowing that the battery will not be charged for more than 12 months, it makes sense to increase the starting charge. (See also: BU-702: How to Store Batteries )
Tests
The Cadex laboratory tested 294 cell phone batteries that were returned under warranty. An advanced charger with an analyzer allowed to restore 91% of cells with a capacity of 80% and more. Deep dormant cells constituted 30% of the entire group. After recharging, they regained their working order. 9% of the batteries failed to wake up. All recovered packages have been returned to service and functioning without showing any defects. This case shows that there is a good chance of recovering a dormant battery.
Last updated on 2016.03.07
The article is a translation of the material contained on the website: BU-808a: How to Awaken a Sleeping Li-ion
Feel free to discuss the topic.
Marek
Subject:
This article provides information on why batteries can go to sleep and how to restore them to service.
Dormant battery
Li-ion batteries contain in their structure protective circuit which prevents them from being damaged in the event of over-discharge. This important element disconnects the link making it theoretically useless. After an extended period of time, the battery may go into sleep mode due to self-discharge, which is partly caused by the cell's chemical processes and partly by the battery protection circuitry constantly consuming a small current. Depending on the manufacturer, the protection circuit is activated at a voltage from 2.2V / cell to 2.9V / cell. (See also BU-802b: Elevated Self-discharge )
Waking up from sleep
There are chargers that can wake a dormant battery by increasing its voltage in order to deactivate the protection system (boost). Chargers without this option detect the battery as damaged and will not charge the dormant battery. Wake-up is based on applying voltage to the battery contacts while limiting the current to a small level. In this way, the protection circuit receives power and the battery voltage can rise above the threshold above which normal charging begins. Typically the reviving process takes about a minute. If the cell voltage does not rise to the expected level then the cell should be considered damaged. Figure 1 shows in a simplified way what the wake-up procedure is.
Figure 1. Waking up a Li-ion battery from sleep mode.
Risk
Do not use this method on batteries whose voltage has fallen below 1.5V / cell and has remained at this level for a week or more. Copper bridges inside the cell can lead to a partial or complete short circuit. Charging such a battery can cause process instability, excessive heat generation, including the risk of fire. Advanced chargers can recognize such situations and stop the process of reviving a dormant cell.
Waking up the cell carries one more risk - polarity reversal. Most chargers can recognize a cell connected inversely, as long as there is voltage on its terminals. The dormant battery does not show any voltage at the terminals, so be very careful as there is a risk of connecting the battery upside down. In the absence of voltage, the charger may try to wake up the battery, but if the polarity is reversed, the cell will be permanently damaged. Li-ion cells are much more sensitive to polarity reversal than other types of batteries.
Sleep prevention
Storing lithium-ion batteries is not an easy topic at all. On the one hand, manufacturers recommend maintaining a state of charge in the range of 40% - 50% of the nominal value, but on the other hand, self-discharge of cells, especially at elevated temperatures, may cause excessive discharge and entering the sleep state. Knowing that the battery will not be charged for more than 12 months, it makes sense to increase the starting charge. (See also: BU-702: How to Store Batteries )
Tests
The Cadex laboratory tested 294 cell phone batteries that were returned under warranty. An advanced charger with an analyzer allowed to restore 91% of cells with a capacity of 80% and more. Deep dormant cells constituted 30% of the entire group. After recharging, they regained their working order. 9% of the batteries failed to wake up. All recovered packages have been returned to service and functioning without showing any defects. This case shows that there is a good chance of recovering a dormant battery.
Last updated on 2016.03.07
The article is a translation of the material contained on the website: BU-808a: How to Awaken a Sleeping Li-ion
Feel free to discuss the topic.
Marek
Comments
Another interesting article. Thanks. [Read more]
How to check it if, as you write yourself,: ? ;) [Read more]
Maybe a few definitions for discussion purposes to start with: The cell is a reservoir with electrodes and electrolyte. The battery is a cell + safety electronics. If the cell can be accessed, the... [Read more]
Gentlemen, I do not know how you, I only have Imax B6 (original), unfortunately it does not have the function of waking up the cells, but it successfully manages to lift the cells manually by setting the... [Read more]
It should be mentioned that the most popular 18650 cells or modeling packages do not have any protection system apart from protection against overheating. We will not wake them up, because at 0V they will... [Read more]
18650 maybe not to zero, but 0.1V and they get up [Read more]
I have a 18650 complete with a Dell package. Unfortunately, I left it for half a year, they have gone to zero and nothing can pick them up anymore. I cracked the battery, cut it into individual pieces,... [Read more]
A colleague probably wants to lose his paws by giving 8A, I pick up the 18650 with the Imax B6 charger, I charge first as NiCd 1A until it gets 3V, checking if it does not heat up and then like a normal... [Read more]
I picked up the phone battery from 0.00V, it only had overheating protection. [Read more]
You learn all your life :) . I did not know about such protection and I managed to revive the battery from the cell, which showed 0 V by accident. I wanted to measure the voltage again but I did not notice... [Read more]
There are, for example, guests on ajeglo who sell such picked up akku from junk packages (mainly from laptops) These are generally used garbage batteries Recently, there has been a flock of scandals... [Read more]
You have touched upon a very serious problem of the disposal of used batteries. On the one hand, we have cheap appliances that consume more energy, have a short life span and quickly turn into waste. ... [Read more]
Rather, it is a corpse resuscitation because a properly used battery does not require magic tricks It is enough to recharge regularly once a year :) Situations in which the battery cannot be recharged... [Read more]
But bullshit. The batteries from the phone can be saved more or less like this, but the 18650 from the laptop does not go to sleep ... [Read more]
With this article, I'll try to wake up a few batteries that I thought were completely dead. [Read more]
Fact. If it is not, then the link is secured. But also some 18650 0V ones can be raised. [Read more]
https://www.youtube.com/watch?v=uQ2aicvLSZU&t=1s As a curiosity. Maybe risky, but as you can see it works. [Read more]
The power of the Internet and YT in particular ... [Read more]
I did that too, but no drilling. There is something like a bimetallic fuse under the positive pole, only one time. Sometimes it is possible to save such a link by gently pressing the fuse so that it returns... [Read more]