In my project ,We wanna know the battery's SOC basic on Coulomb Counter,MCU can read battery cell and type, How to design a software to count the SOC, in "4015fb.pdf", LTC4015 Digital System Usage Example 1: Coulomb counter and Low Limit Alert Only, " Register QCOUNT is initialized to reflect the known state of charge, QCOUNT_PRESCALE_FACTOR is written for optimumrange and resolution,"
But I have questions that if i don't know QCOUNT and SOC, How to get it basic kind of battery and cell，In pdf docment"EXAMPLE: Setting QCOUNT_PRESCALE_FACTOR andinitializing and calibrating QCOUNT:" I have read it ,Now i wanna some advanced application detail,TKS!
The LTC4015 includes only a coulomb counter. It leaves the SoC estimation up to the customer's design. So, there's no "correct" way, and there are many ways to approach the problem.
Ultimately, approximating the SoC (before starting the coulomb counting) comes down to monitoring the battery voltage under different load / temperature conditions. There can be a lot involved depending on how accurate you need to be.
If your battery will never be disconnected, you can have a somewhat simple SoC approximation where you assume that the SoC at the end of charging is 100% and the SoC at full discharge is 0%, interpolating between there.
For more information on the battery's charge voltage over time, I recommend that you consult charge/discharge characteristics from the battery's datasheet to get some of these numbers.
Here are some online resources:
TKS your reply, anther question： If absent power from VIN, Max current is limited 8A with 4mR sample resistor, or not limited, basic on system load
There is no discharge current limit in theory.
That said, you can't pull spikes of current that are MUCH higher than the programmed charge current. To be specific, there's an abs max of 0.3V differentially across the sense lines, so with your 4mOhm resistor, you should not exceed 75A (even instantaneously).
That's probably much more than you were anticipating to provide to the load, but it may be helpful to know if you are dealing with hot-swapping the battery at a later time (which will cause current inrush that may reach that level instantaneously).