Undercharging of li-ion is very popular them for discussion.
There are a lot of topics on the Internet with such words:
"I bought a charger, it charge to 4.1x volt is it faulty?"
"My expensive *BRAND_NAME* chargerer charge only to 4.1x. Should I send it back?"
Is undercharging so bad?
I have used many different chargers for the last few years. Nitecore i2, F1; Miller ML-102v8/v9; Xtar MC1, MC1 ANT, SP1; LiitoKala Lii 100. None of them charge batteries exact to 4.2v. LiitoKala Lii 100 overcharge to 4.24v and lowest voltage was in Nitecore F1, just 4.09v. All other charge from 4.15 to 4.18 volts. (I mean charger cutoff voltage, not battery voltage after charging)
Then I thought about it. Is there a charger with cutoff voltage at exact 4.2v? I began to search and came across an interesting article on Tesla's website
This post was published more than 10 years ago!
https://www.tesla.com/blog/bit-about-batteries
It says:
"Voltages over 4.15V/cell (about 95 percent state of charge [SOC]) and voltages below 3.00V/cell (about 2 percent SOC) cause more stress on the insides of the cell (both physical and electrical)"
"There is a huge difference in cycle life between a 4.2V/cell charge (defined by the manufacturers as “fully charged” and a 4.15V/cell charge. 4.15 volts represents a charge of about 95 percent. For this reduction of initial capacity (5 percent), the batteries last a whole lot longer. Unfortunately, further reduction of charge has a much smaller benefit on cycle life."
a huge difference in cycle life between a 4.2V/cell and a 4.15V/cell charge
the batteries last a whole lot longer
What does that means? How many more cycles? dozens? hundreds?
Is this relevant for modern high capacity batteries like GA, MJ1,
There are a lot of topics on the Internet with such words:
"I bought a charger, it charge to 4.1x volt is it faulty?"
"My expensive *BRAND_NAME* chargerer charge only to 4.1x. Should I send it back?"
Is undercharging so bad?
I have used many different chargers for the last few years. Nitecore i2, F1; Miller ML-102v8/v9; Xtar MC1, MC1 ANT, SP1; LiitoKala Lii 100. None of them charge batteries exact to 4.2v. LiitoKala Lii 100 overcharge to 4.24v and lowest voltage was in Nitecore F1, just 4.09v. All other charge from 4.15 to 4.18 volts. (I mean charger cutoff voltage, not battery voltage after charging)
Then I thought about it. Is there a charger with cutoff voltage at exact 4.2v? I began to search and came across an interesting article on Tesla's website
This post was published more than 10 years ago!
https://www.tesla.com/blog/bit-about-batteries
It says:
"Voltages over 4.15V/cell (about 95 percent state of charge [SOC]) and voltages below 3.00V/cell (about 2 percent SOC) cause more stress on the insides of the cell (both physical and electrical)"
"There is a huge difference in cycle life between a 4.2V/cell charge (defined by the manufacturers as “fully charged” and a 4.15V/cell charge. 4.15 volts represents a charge of about 95 percent. For this reduction of initial capacity (5 percent), the batteries last a whole lot longer. Unfortunately, further reduction of charge has a much smaller benefit on cycle life."
a huge difference in cycle life between a 4.2V/cell and a 4.15V/cell charge
the batteries last a whole lot longer
What does that means? How many more cycles? dozens? hundreds?
Is this relevant for modern high capacity batteries like GA, MJ1,
35E ? Does anyone have the experience of cycle to cycle overcharging or undercharging? How does this affect the batteries in real life use?