Connect 3 Lithium Polymer battery with different capacity in parallel

Sajin M

Hi,

I am working on an IoT product with has a total current requirement of 1.3 A at the peak. Due to space constraint, we decided to select Li-Po battery with capacities one with 600 mAh other two with 350 each and the voltage rating are the same 3.7V. to get total 1300 mAh we are connecting them parallel. Now we are looking for a charging IC which will support this parallel configuration with different capacities and same voltage rating Li-Po batteries. How can we solve it?

over 6 years ago

0 Jeff F over 6 years ago

TI__Guru**** 166246 points

Sajin,

TI does not have an IC that can charge parallel batteries with different capacities and then provide a single output to the system. My recommendation would be for two separate chargers with their outputs diode OR'd together. What is your input power source voltage and current?

0 Sajin M over 6 years ago in reply to Jeff F

Intellectual 360 points

Dear Jeff,

Thank you for replay. The input voltage is 5V and the maximum input current will be 2 A.

The Apple iPhone Xs Max using 2 different capacity cells in parallel to get higher capacity. And they are using one of the charging IC from TI. How it is possible?

0 Jeff F over 6 years ago in reply to Sajin M

TI__Guru**** 166246 points

Sajin,

I checked with my colleagues and apparently it is okay because the cells will self balance but you have to set the charge current lower to accomdate the lower capacity cells.

0 Sajin M over 6 years ago in reply to Jeff F

Intellectual 360 points

Thank you, Jeff. So I can connect them in parallel right?

Can every charging IC with suitable charging and discharging current ratings and having single cell support will work with this parallel connection of battery?

0 Jeff F over 6 years ago in reply to Sajin M

TI__Guru**** 166246 points

Yes and yes. Keep in mind you have to charge at the 1C rate for the lower capacity battery.

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Connect 3 Lithium Polymer battery with different capacity in parallel