Hi Sir ,
We used BQ20Z655-R1 for 4S2P battery packet application . The cell design capacity is 2600mAh, the battery packet design capacity is 5200mAh.
I want to check some question ：
1. The term voltage is set 12V ,the Remaining Capacity will change to 0mAh if the term voltage is decrease to 12V ?
2. The term voltage determined by the minium cell voltage or the battery packet voltage?
3. What is the Max accuracy of the Remaining capacity and SOC?
I test 58 pcs 0.25C discharge capacity and read 58 pcs the remaining capacity and Full charge capacity , but i found the the max Error can reach -14%.
I want to check how many accuracy is correct ?
The error =(0.25C Discharge Capacity-Remaining Capacity)/0.25C Discharge Capacity*100%.
All the 58 pcs battery packets are charge to full , i use the 0.25C constant current to discharge to the term voltage 12V , the battery packet discharge capacity value see the form table.
| SN | Remaining Capacity(mAh) | Full charge Capacity(mAh) | 0.25C Discharge Capacity(mAh) | Error |
| B0001 | 4657 | 4661 | 4572.2133 | -2% |
| B0002 | 4604 | 4687 | 4554.7239 | -1% |
| B0003 | 4707 | 4711 | 4561.3537 | -3% |
| B0004 | 4864 | 4872 | 4560.6127 | -7% |
| B0005 | 4767 | 4892 | 4568.9078 | -4% |
| B0006 | 4673 | 4864 | 4558.4959 | -3% |
| B0007 | 4688 | 4864 | 4552.9872 | -3% |
| B0008 | 4679 | 4867 | 4567.2387 | -2% |
| B0009 | 4862 | 4864 | 4535.5003 | -7% |
| B0010 | 4937 | 4937 | 4552.2565 | -8% |
| B0011 | 4701 | 4863 | 4537.3419 | -4% |
| B0012 | 4842 | 4842 | 4559.596 | -6% |
| B0013 | 4876 | 4876 | 4569.7124 | -7% |
| B0014 | 5035 | 5036 | 4542.9441 | -11% |
| B0015 | 4852 | 4852 | 4541.7966 | -7% |
| B0016 | 4899 | 4903 | 4580.5904 | -7% |
| B0017 | 4917 | 4920 | 4583.6926 | -7% |
| B0018 | 4804 | 4901 | 4563.0601 | -5% |
| B0019 | 4896 | 4896 | 4563.3305 | -7% |
| B0020 | 4877 | 4877 | 4572.7608 | -7% |
| B0021 | 4882 | 4882 | 4579.9871 | -7% |
| B0022 | 4884 | 4884 | 4566.4433 | -7% |
| B0023 | 4872 | 4878 | 4582.0717 | -6% |
| B0024 | 4842 | 4847 | 4497.2876 | -8% |
| B0025 | 4845 | 4848 | 4517.8233 | -7% |
| B0026 | 4834 | 4848 | 4521.9483 | -7% |
| B0027 | 4807 | 4817 | 4488.5433 | -7% |
| B0028 | 4763 | 4849 | 4516.7277 | -5% |
| B0029 | 4863 | 4863 | 4518.5713 | -8% |
| B0030 | 4719 | 4846 | 4483.8668 | -5% |
| B0031 | 4868 | 4872 | 4570.9449 | -6% |
| B0032 | 4899 | 4899 | 4570.7095 | -7% |
| B0033 | 4941 | 5042 | 4557.0246 | -8% |
| B0034 | 4807 | 4807 | 4555.9827 | -6% |
| B0035 | 4930 | 4930 | 4559.1955 | -8% |
| B0036 | 4900 | 4900 | 4562.6909 | -7% |
| B0037 | 4852 | 4852 | 4567.7774 | -6% |
| B0038 | 4850 | 4850 | 4563.943 | -6% |
| B0039 | 4929 | 4929 | 4564.2512 | -8% |
| B0040 | 4857 | 4876 | 4572.081 | -6% |
| B0041 | 4885 | 4903 | 4563.4447 | -7% |
| B0042 | 5019 | 5041 | 4567.1306 | -10% |
| B0043 | 4920 | 4924 | 4549.2557 | -8% |
| B0044 | 4828 | 4871 | 4558.3545 | -6% |
| B0045 | 5054 | 5058 | 4564.9557 | -11% |
| B0046 | 5057 | 5061 | 4561.3739 | -11% |
| B0047 | 4749 | 4914 | 4512.0786 | -5% |
| B0048 | 5008 | 5067 | 4506.067 | -11% |
| B0049 | 4524 | 4587 | 4482.0521 | -1% |
| B0050 | 4978 | 5033 | 4494.9687 | -11% |
| B0051 | 5080 | 5131 | 4466.7616 | -14% |
| B0052 | 4773 | 4928 | 4489.9042 | -6% |
| B0053 | 4962 | 5035 | 4449.9286 | -12% |
| B0054 | 4927 | 4994 | 4454.6406 | -11% |
| B0055 | 4714 | 4781 | 4529.9372 | -4% |
| B0056 | 4538 | 4696 | 4548.9095 | 0% |
| B0057 | 4865 | 4865 | 4545.0232 | -7% |
| B0058 | 5135 | 5136 | 4541.9212 | -13% |
Thanks ！
Billy Xu
