Hi there!
In our future product we plan to use the bq27541-G1 gas gauges. The IC will reside on the system PCB since the cell will be non-removable (by the end user).
We tried to figure out how to configure the bq27541-G1 for this scenario but we found the available information very confusing. This is why I hope to get some clarifications here.
Most confusing we find the diversity of software tools available: there is bqEVSW, GaugeStudio, bqEASY and bqCONFIG. Not all programs seem to be compatible with all gas gauges. And which program has to be used for which purpose during gas gauge calibration and configuration? Without having a physical prototype here at this time we cannot really test any of the mentioned programs. Situation becomes even more complicated with the subtle differences between bq27541-V200 and bq27541-G1, so we are unsure if the described calibration procedures (for the by27541-V200) are still valid for the bq27541-G1.
From my understanding, the steps needed for Gas Gauge Configuration are:
- Calibration (CC Offset, Voltage, Temperature, Current).
- Cell Chemistry Profile Programming
- IT Learning Cycle
- Generate Golden Image
Now I have some questions about how these steps should be done (and which software is needed).
- Looking at the Gauge Studio quick start guide, the Calibration procedure is embedded in Gauge Studio. Looks good an easy.
- Cell Chemistry Identification. We downloaded SLUC138, Mathcad Chemistry Selection Tool (Rev. BQ). Our Cell (SDI: ICR18650-26F) is found in the Chemistry Selection Table (ChemID: 1165). How do we program the chemistry information into our bq27541-G1? There is an AppNote (SLUA544, How to generate Golden Image…) where bqEASY is used for this task. Is this still the “tool of choice”?
- The Learning Cycle.In AppNote SLUA597 “Achieving The Successful Learning Cycle” the individual steps needed are clearly shown. However, this paper does not mention anything about the Tools (software) to use for this procedure. In the aforementioned SLUA544 it says, Learning Cycle can be performed automatically using bqEASY-Software. There is also a load circuit (controlled by EV2300 through a small relay) shown, which we are planning to use. Can you please confirm that this feature is still available for our bq27541-G1? Does the Gauge Studio have this procedure implemented or which of the EV software has to be used?
- Golden Image Generation.Same question as above, which tool can/should be used when talking about the bq27541-G1?
Besides these basic questions about getting started with the bq27541-G1 there are also a few design specific questions I could not answer myself from the datasheets. I hope someone can enlighten us here as well:
- What do we have to do if (during prototyping) the cell has to be removed from the gas gauge and is reconnected later? Do we have to reset the IT algorithm every time? If so, can this be issued by the host system microcontroller or do we have to go through the configuration process with the EV software (Gauge Studio) again?
- On the host system PCB where the bq27541-G1 will be placed, the charger IC is located, too. For safety reasons, this charger IC has to be connected to the cell’s thermocouple. So the cell’s thermocouple cannot be connected to the by27541-G1. What should we do in this case, use the internal temperature sensor for the IT algorithm? Adding a second thermocouple to the cell is not really an option.
I have the feeling as if you are merging all the former software tools (bqEVSW, bqEASY and bqCONFIG) into the new Gauge Studio. The current version really looks great and we are sure that this program will simplify working with the TI gas gauges in the future. But at the moment we are not sure if all features needed for (easy) configuration of the bq27541-G1 are already implemented. I hope that you can clear up our confusion here a little bit.
I apologize for this heap of questions. But I think your answers will also help to guide other users / customers who are trying to get started with the bq27541-G1 and the available tools.
Thank you!
Best regards,
Daniel