Other Parts Discussed in Thread: EV2400, GPCCHEM
I'm working on the correct safety and initial gauge parameters for my BQ27742.
So far I have read the datasheet, large sections of the User Guide as well as SLUA544 (which seems out of date now).
I have an EV2400 and a custom board with the BQ27742 on it (schematic was reviewed by TI). BM studio can talk to it just fine.
I'm using a TI BQ25890HR USB charger to charge my battery pack. The TI charger will trickle charge a cell up until 2.8V when it will turn on the full charge current (I will have to limit that based on my batteries). When it reaches 4.208V - 100mV it will begin to taper off the charge current until less than 256mA flows. Then it will turn off.
I'm using two Grepow LIPO batteries in parallel, 600mAh x 2 = 1200mAh. Discharge at least 4A, charge 0.5C.
Based on my reading I think I have to set the following values in the data flash.
Over Voltage Protection - 4390mV. The charger will shut off at 4208mV as primary protection.
Under Voltage Protection - 2800mV.
Charge Over Temp - 65C. Charger will stop at 60C.
Charging Voltage - 4208mV. Note the charger turns off at this same 4208mV - 100mV
Tapper Current - 256mA. Matching the chargers shutoff current
Tapper Voltage - 100mV. Matches chargers -100mV setting
Design Voltage - 3800mV.
Cycle Count threshold - 1080mAh (90% of capacity)
Design capacity - 1200mAh
Design energy - 4560mWh
I also think I have to set the following "protector settings"
OC Discharge -34mV or 6.8A
OC Charge - 6mV or 1.2A (must limit charger current in charger to 0.5C or 600mA)
Have I missed any important safety configurations?
Is this enough to get my gauge sort of working? My battery vendor wasn't in the chemistry list so I didn't know what to choose there. Maybe I have to follow an updated procedure to figure it out.