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.

 

What current are you trying to get? What current(s) do you get? What was the battery voltage at the time? Schematic?

 

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

 

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.

 

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

 

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

Bob

 

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.

 

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

 

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

 

I must admit that I did used a pair of pliers to pound in a nail once.

Bob

 

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

 

not enough power =

too few electrons to complete the message?

 

too few electrons to complete the message?

no i forgot to toggle the javascript back on (would allow finishing your msg. in real time . . . switching off the javascript while typing on a slow PC)

 

????????????????????????????????????????????? are you aware the(re's a) built in protection for some Li-Ion packages

If you got the ans please reply i'm also stuck on same problem.

 

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 !!