Other Parts Discussed in Thread: BQSTUDIO, BQ34110
Hello,
I am using the BQ34110EVM with bqStudio to gauge a 150Ah 12V PbA battery. I am attempting to conduct the initial capacity learning phase by conducting a "qualified discharge." I am able to successfully begin a qualified discharge (the [VDQ] bit sets); however, the learning phase is unsuccessful because the [EDV2] an [EDV1] bits set very premature. The gauge appears to be reading the voltage correctly, and when the [EDV2] and [EDV1] bits set (whose levels are programmed to 1863 and 1837, respectively) the voltage measurement is nowhere near their values.
A couple things to note:
1) I calibrated the current by scaling it by a factor of 6 due to our high capacity battery and our currents up to 17 A.
2) Because of our high currents, I removed the 10mOhm sense resistor from the EVM and attached a 5mOhm 5Watt sense resistor external to the board. This ensures our currents are safe and that the voltage that appears at the SRN/SRP pins are within the spec limits.
3) I performed the Board Offset calibration. The CC Gain value changes when I calibrate the current using a scale factor of 6 (it changes to a value of ~34mOhm). I assume the reason the value is ~6x the actual sense resistor value is because of the scaling.
4) I was not able to calibrate the voltage. Using a Voltage Divider value of 19205mV gave me voltage readings that were pretty close to the actual voltage so I continued with the test despite not being able to calibrate the voltage correctly.
5) I can provide my .srec and .log files but this forum will not let me post them here for some reason.(***UPDATE: See files below in reply. I had to compress them first)
6) I enter Design Capacity and Learned Full Charge Capacity values of 25000mAh and expected the vale of Full Charge Capacity to be 25000mAh, but it is not: it is 23100 (so is RC). When the discharge starts, after about 5 seconds the SOC drops to 7%, [EDV2] sets, and RC changes to 1617mA. After another few seconds, SOC changes to 3%, [EV1] sets, and RC changes to 693mAh.
7) Another thing I am noticing is that after the RC/SOC drops to these lower values, if I then begin charging the battery, the RC value does not increase.
8) There is a register in bqStudio called "Raw Coulomb Count" that does not exist in the bq34110 datasheet or user guide and its value is always zero (during both discharge and charge).
Can anyone tell me why the [EDV2] and[ EDV1] bits would be setting like this so I can complete a successful capacity learning phase?
Thanks so much.
