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I have a dead Li-ion battery from a Wifi device. Since I didn't use it for a couple of months, Its dead now. I have read somewhere that boost charging is used to charge and bring the battery back to its original capacity. How much volts and current should I supply to bring it back to life?

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    \$\begingroup\$ If you have to ask this question, you may be a bit over your head. Improper handling and charging of Li-ion cells can be quite dangerous. \$\endgroup\$ – Shamtam Oct 31 '17 at 15:31
  • \$\begingroup\$ What is the size of this battery? The answer depends on this. If the actual capacity is not known, tell the physical dimensions of the battery. \$\endgroup\$ – Ale..chenski Oct 31 '17 at 17:56
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You can't "boost charge" a Li-Ion battery. When you say it is "dead", I assume it doesn't deliver any voltage/current. There could be two scenarios of what has happened.

  1. The battery has a built-in protection circuit. When the (internal) cell voltage drops below certain threshold (like 2.5-2.9V), the circutrty disables the battery output.

  2. The cell gets drained to actual zero due to self-dicharge parasitics. Then it is formally "dead".

There is a third scenario when the cell went dead after a catastrophic overdischarge (short), which destroyed internal conductors. I assume this is not the case here.

In first two cases there is a chance for recovery. You should apply a very modest "precharge" current (say, 100 mA). If the cell is just overdischarged and is shut down due to protection, it will quickly gain some voltage above the cut-off thershold, and the protection circuit will disengage. Then you charge the battery using normal means of your device.

If the cell has no protection and is dead by electrochemical depletion, there is still a chance that it will come back to life. However, studies show that the process of recovery is unpredictable, and in no case the cell can be restored to its original capacity. The result can be anywhere. See also some relevant discussion here.

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Try do a couple of charge / discharge cycles. First charge up to 4.1 V then use a power led or a power resistor like 10 ohms for discharge until the battery reaches 1.2 volts. Then do the same thing more 2 times. Usually, it works for me.

Also, Check this article. It may help you. http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

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  • \$\begingroup\$ Should I use a 5V and 1amp power supply for that or a bit higher voltage? Thanks for your response. \$\endgroup\$ – mystical_starseed Oct 31 '17 at 15:50
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    \$\begingroup\$ That treatment works for me to get nice battery fires too \$\endgroup\$ – PlasmaHH Oct 31 '17 at 15:56
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    \$\begingroup\$ @farzand I highly recommend you read the above link on Li-ion battery charging thoroughly. I've made that mistake the first time I charged a Li-ion battery without reading about it and next thing I remember was a bomb that went off in my garage. The max charging for a Li-ion battery is 4.2V(never exceed this limit!). Also what is the capacity of the battery? \$\endgroup\$ – The_Vintage_Collector Oct 31 '17 at 16:00
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    \$\begingroup\$ Safety Concerns with Li-ion. Technical summary of lithium battery failure mechanisms: Lithium Battery Failures. To put it more bluntly, @farzand: Desist, because you don't seem to know what you're messing with. \$\endgroup\$ – Nick Alexeev Oct 31 '17 at 16:02

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