# Increasing the number of parallel cells for batteries

I am using Texas Inst IC for a lithium ion battery which is in the 4Serial-3Parallel cell configuration. In addition, I don't use LED or LCD in this lithium-ion battery. My cells have 3500mAh capacity.

I am planning to increase the number of parallel cells but I am not sure about maximum number of parallel cells(for example 4Serial - 8 Parallel Configuration).

Especially, my concern is about cell balancing. Becasue internal balancing current is 5mA.

What are your recommendations? Can I use this PCB with 4Serial-8Parallel configuration?

EDIT:

As I said before, I have PCB(with bq20z655-r1) and it is working very well for 4Serial-3Parallel configuration. Now I am planning to use 2 parallel PCB. I mean 4S-3P + 4S-3P with 2 PCB. Please check the image:

Maybe It can be solve something for balancing. What is your idea for that?

Please check this document for cell balancing: http://www.ti.com/lit/an/slua340c/slua340c.pdf

• is the 3500mAh capacity per cell or per 4s3p configuration? – Pop24 Mar 1 '18 at 9:41
• On the website it states max capacity is 32000mAh, so with regard to capacity alone you'd be safe with 8 Parallel. 8*3500 = 28000mAh which is less than 32000mAh – Pop24 Mar 1 '18 at 10:00
• "Note: I have to use this ready-made design" do you mean you have to use the circuit features as tht typical application page 20 of the data sheet? – Pop24 Mar 1 '18 at 10:01
• where do you get the figure 5mA from. The current is dictated by the cell voltage at the time of balancing and the internal resistance, which can vary according to the datasheet from 200 to 600 Ohms. based on 4V cell voltage, thats 7-20mA – Pop24 Mar 1 '18 at 10:03
• if your primary concern here is cell balancing i would not use this IC. Personally i use LT6811 this way you can control cell discharge externally to the IC itself (Higher balancing currents can be achieved) – Pop24 Mar 1 '18 at 10:07