Other Parts Discussed in Thread: BQ27411DRZR-G1B, BQSTUDIO, EV2400
Hello,
For our current design we use the BQ27411DRZR-G1A fuel gauge. Unfortunately, this chip is now unavailable and I need to find a direct replacement. My first thought is the BQ27411DRZR-G1B. I understand that the G1B defaults to a higher max charge voltage (4.3V) than the G1A (4.2V) and that the CHEMID numbers are different between these two chips.
On the TI E2E forum I have read the following:
1. The G1B can be a direct substitute for the G1A.
2. the max voltage on both the G1A and G1B are programmmable and I can set it to 4.2V on the G1B
3. the CHEMID is hard coded and I will not be able to change it. Therefore, the G1B could cause a reduced accuracy.
I did some more reading and came across the BQStudio tool. From what I understand, this tool will allow me to quantify my battery's discharge behavior and pick the appropriate CHEMID accordingly. ( "Application ReportStart Guide for BQ Products" page 11) Here I get confused because I thought the CHEMID was hard coded into the chip according to the forum response.
To give some more background information, we always used the BQ27441-G1A pretty much out of the box with only doing some minor programming: design capacity, design energy (data sheet recommended design capacity x 3.7) and termination voltage. We have will be using several types of LiPo batteries PKCell LP103450 4.2V, 2000mAh, and are considering moving to using two different parallel configurations of 3P and 5P of a Grepow 4.2V, 702430, 850mAh/cell (3P=2550mAh, 5P = 4250mAh). With all three batteries, the BQ24711-G1A seems to perform reasonably well in determining battery SOC and health. However, since we never used the BQStudio tool I can imagine a lot of improvement is possible. This will need to be a longer term project. Meanwhile:
1. Considering what I just told you about our already minimally calibrated setup, my feeling is that I can substitute the G1A with the G1B without losing too much accuracy and simply reprogram the max charge voltage setting. Is this a correct assessment?
Long term, I assume we would benefit from getting an EVM board for the BQ27411-G1A, and the EV2400 evaluation tool to determine the correct chem id and program the fuel gauge accordingy (if this is possible).
2. Can you please explain which is correct or am I misunderstanding something?
3. What are the possible negative effects on the fuel gauge measurements of using cells in parallel that I should keep into consideration and what can I do to minimize those?
Finally, I would appreciate any other suggestions (eg other substitutes or improvements) or any further recommendations.
Sincerely,
Kornelis
