Other Parts Discussed in Thread: BQSTUDIO
Tool/software: BQ Studio
We are currently using this fuel gauge in one of our new designs and we are currently facing problems in calibrating it.
References used:
https://www.ti.com/lit/ug/sluucd5/sluucd5.pdf
https://www.tij.co.jp/jp/lit/an/slua903/slua903.pdf
Setup:
- BQ27427 EVM
- Interfaced using EV2400 with BQ Studio
- Custom Li Ion battery pack
- Design capacity: 1250mAh
- Discharge terminal voltage: 3000mV
- Charging terminal voltage: 4400mV
- Nominal voltage: 3850mV
- Configs set using BQstudio
-
OpConfigD[Chem ID]
3142 [10]
Terminate voltage matches the current battery.
Design capacity
1250mAh
Design voltage
3850mV
Charging Terminate Voltage / Taper Voltage (109)
4400mV
Taper Rate
182 [0.1h]
Calculation: 1250mAh = C, 62.5mA = Taper Current from datasheet.
1250mAh / (110% x 62.5mA) = 18.18 hours. / 0.1 = 182
Discharging Terminate Voltage
3000mV
Dsg Current Threshold
250 [0.1h]
Calculation: Discharge current set to 50mA. C = 1250mAh Therefore
C / ( C / 25 x 0.1) = 250 [0.1 h]Chg Current Threshold
225 [0.1h]
Calculation: Charge current threshold set to 55.5mA. C = 1250mAh, therefore:
C / ( C / 22.5 x 0.1) = 225[0.1 h]Quit Current
313 [0.1h]
Calculation: Set quit current even lower to 40mA. C = 1250mAh
C / ( C / 31.25 x 0.1) = 313[0.1h]Dsg Relax Time
60s
Keeping defaults
Chg Relax Time
60s
Keeping defaults
Quit Relax Time
1s
Keeping defaults
OpConfig[Temps]
10
Host written temperature used as temp source
Sleep Current
10mA
Keeping default for the moment
-
Questions
- According to the Learning cycle reference manual, the following commands cant be found in BQstudio
- IT Gauge enable (0x21)
- The following status registers are not available
- GAUGE_EN
- RDIS
- QEN
That said how can I calibrate the gauge to our cell? Seems like the calibration reference guide is not valid for this Fuel gauge(BQ27427)
I want to calibrate it create a golden image so I can export the RA tables and config values.
Thank you and will be waiting for your response.
Sincerely,
Chamith
