Minimum voltage a 3.7v battery can be recharged from

Thread Starter

Siva Manasan

Joined Nov 14, 2017
10
After how low a battery discharged it can be brought back to life using a
1.typical charger
2.Any method possible(Mention the method)
 

dl324

Joined Mar 30, 2015
9,154
There is no hard and fast rule. Lead acid are less forgiving than most. Reverse voltage of half a volt, caused by batteries being in series, will kill many types of rechargeable batteries.
 

KeithWalker

Joined Jul 10, 2017
460
General purpose Lithium Ion battery charger protection circuits usually cut off the discharge when the voltage drops to 3 volts. The chargers will not recharge a battery if the voltage drops much below this voltage. If the voltage drops below 2.7 volts, the cell will be damaged and will no longer hold a charge. If the voltage drops to below 3 volts but above 2.7 volts, the cell can usually be recovered by applying a current controlled power supply directly across the output terminals until the voltage increases to above the charger cut off voltage. Then the cell can be recharged normally.
The figures I quoted are typical. If you are working with a battery from a specific manufacturer, you should check the data sheet for the actual values.
 

Thread Starter

Siva Manasan

Joined Nov 14, 2017
10
I've seen some videos in youtube using a method called "bump charging" Is this possible? Are there there any disadvantages or long-term problems other than safety? Will this recovered li-ion battery function as normal afterwards? Why regular chargers stop charging if dropout voltage get lower than 3v(Any safety concerns)?

Reviving a battery with 0.3v -
Reviving a battery with 0.5v -
 

Audioguru

Joined Dec 20, 2007
11,251
Batteryuniversity.com and most Lithium battery charger IC datasheets say that a Lithium battery cell that is discharged too low is ruined.
They say when the voltage is too low then the Lithium ions have turned into dangerous explosive and flammable metallic Lithium.
Most Lithium battery charger ICs attempt to charge at a low current when a low voltage is detected and if the voltage does not rise then it stops and gives an error message.
 

Ylli

Joined Nov 13, 2015
799
In other words, a Lithium battery that has been over-discharged and then forced to take a recharge becomes a serious fire hazard.
 

KeithWalker

Joined Jul 10, 2017
460
In other words, a Lithium battery that has been over-discharged and then forced to take a recharge becomes a serious fire hazard.
No! As I explained above, If the voltage has dropped to below the cut off level of the charger, but is still above 2.7 volts, it is quite safe to charge it from an external source. The usual charge rate is 37% of the current stated in the ampere hour capacity of the battery. If the voltage has dropped to below the recovery level, it will simply not take a charge.
It becomes dangerous when a cell is charged at a higher current or to a higher voltage than is recommended, or if the cell is physically damaged. Then the temperature can rise and may get to a point where the cell will ignite and explode.
 

Ylli

Joined Nov 13, 2015
799
Re-read post #6 above, and the link to BatteryUniversity in post #3. A lithium battery excessively discharged changes internal chemistry, which makes it less stable. *THAT* is why a charger will not charge if the terminal voltage is too low.
 
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