Is it possible to achieve CC(Constant Current) using AX3112 to charge Li_Ion Batteries?!

Thread Starter

gilsg7

Joined Feb 26, 2016
2
We are using AX3112 for Charging Lithium Ion Batteries and now we are facing a problem that we are not getting proper current. It is varying. Please suggest a solution. I have attached the datasheet of AX3112 and we have used the same reference design for four cells.
 

Attachments

BobTPH

Joined Jun 5, 2013
4,769
Why not use one of the many LIIon charger chips instead? These handle the entire charging regimen, transistioning from constant current to constant voltage to top-off.

Bob
 

crutschow

Joined Mar 14, 2008
29,504
It can be dangerous to charge Li ion batteries using a constant current.
Suggest you follow Bob's advice and use a dedicated charger chip before you blow up a battery and burn the place down. :eek:
 

Thread Starter

gilsg7

Joined Feb 26, 2016
2
What current are you trying to get? What current(s) do you get? What was the battery voltage at the time? Schematic?
The charging current is 1Amps
we are planning to use 4 lithium ion batteries in series.The battery should be charge in constant current and constant voltage.
up to 4.1V the battery should be charge in CC (1Amps)and 4.1 to 4.2V in CV mode.
we got the constant voltage but not the constant current.
please help to figure it out
 

Attachments

BobTPH

Joined Jun 5, 2013
4,769
If you plan to charge 4 cells in series, you need balancing cricuitry as well. Buy a commercial charger that does this right.

Bob
 

AnalogKid

Joined Aug 1, 2013
9,956
Constant current limiting as a way to protect a power supply output from an accidental overload, and a true constant current output for a specific application such as battery charging are two entirely different things. While the chip you are trying to use has a form of current limiting built in, it is not appropriate for battery charging and does not provide a constant output current when in current limiting mode. Again, it is the wrong part for the job and will not do what you want.

ak
 
Constant current limiting as a way to protect a power supply output from an accidental overload, and a true constant current output for a specific application such as battery charging are two entirely different things. While the chip you are trying to use has a form of current limiting built in, it is not appropriate for battery charging and does not provide a constant output current when in current limiting mode. Again, it is the wrong part for the job and will not do what you want.

ak
Thank you for your reply AK. Actually the problem is the IC can be used for the purpose of charging Li-Ion Batteries. We still have trouble to sort it out. Hope you may gone through the attachment of circuit in the above comments.
 

ci139

Joined Jul 11, 2016
1,799
The charging current is 1Amps
we are planning to use 4 lithium ion batteries in series.The battery should be charge in constant current and constant voltage.
up to 4.1V the battery should be charge in CC (1Amps)and 4.1 to 4.2V in CV mode.
we got the constant voltage but not the constant current.
please help to figure it out
????????????????????????????????????????????? are you aware the(re's a) built in protection for some Li-Ion packages
 

AnalogKid

Joined Aug 1, 2013
9,956
Thank you for your reply AK. Actually the problem is the IC can be used for the purpose of charging Li-Ion Batteries. We still have trouble to sort it out.
And you will continue to have troubles. Actually, the problem is that it is the wrong part for the job.

The current sense transition level has a tolerance of +/-12%. That's a lot, and does not include the accuracy of the current sense resistor. To guarantee that the batteries' peak charging current is not exceeded, you have to decrease the design point by around 15%, and know that the actual charging current might be 30% below optimum. Not very efficient.

Separate from that, you are assuming that the device will transition from CC mode to CV mode at a set output voltage value, but there is nothing in the chip to do that.

"can be used" and *should* be used are not the same. Maybe you can beat it into submission, but it never will perform with the stability and safety of a part designed from the ground up to do this task.

ak
 

ci139

Joined Jul 11, 2016
1,799
not enough power = (a) switch not closing fast enough e.g. device fault , overheating , poor contact (b) false frequency or/and duty (c) poor schottky
 

SAYAKU

Joined Oct 7, 2020
14
The charging current is 1Amps
we are planning to use 4 lithium ion batteries in series.The battery should be charge in constant current and constant voltage.
up to 4.1V the battery should be charge in CC (1Amps)and 4.1 to 4.2V in CV mode.
we got the constant voltage but not the constant current.
please help to figure it out
Did you got the ans please reply if you got it, i'm also stuck on same problem.
I have used synchronous buck converter using a feedback path with PID to produce constant current, However i couldn't tune the PID properly. Please reply !!
 
Top