Hi,
I'm using the BQ34Z100EVM with the EV2300 evaluation module to develop a battery monitoring system for a 12V, 40AH LiFePO4 battery. The BQ34Z100EVM board is set up for Multi Cell operation, with external LED's (the 10 LED's on the board), and a maximum input voltage of 16V. I am using an external current sense resistor setup measuring 0.0045 Ohms.
I am running into problems when I try to configure the data flash, mainly the Design Capacity, Design Energy and Qmax Cell 0 values, as it is limiting me to a value of 32767mAh/mWh. I read on the design notes for a different gauge (http://e2e.ti.com/support/power_management/battery_management/w/design_notes/bq27500-max-pack-capacity.aspx) that the limit for Coulomb counting is set to 32767, and would therefore mean that I need to mis-calibrate the sense resistor to factor this in. I have now set the Design Capacity and Qmax Cell 0 to 20,000mAh, and calibrated the EVM with half the current draw (it's actually drawing 6Amps, but I've entered 3A). Is this the correct thing to do when it was mentioned to 'mis-calibrate' the sense resistor?
Another thing I wanted to bring up was how do I run a learning cycle, and export the learnt values for the data flash constants in a way that it could be written to a custom board that we are designing using a PIC processor over I2C? Is this do-able with a DFI / ROM file, and how would I go about obtaining one for my battery system with the BQEVSW?
Thanks