SOC estimator (coulomb counter / gas gauge) for primary and secondary batteries

[ionutF]

I have  a product with replaceable battery (1S1P) , that can be changed by the user.

User can put primary battery (non-rechargeable) 3,0V or rechargeable battery (3,7V).

The rechargeable battery will be charged outside of the product. So the battery will only discharge inside the product. 

Is there any IC that can be used in order to obtain accurate capacity level, like  a battery gas gauge or coulomb counter?

STC3115-FAQ page says that family  STC311x  could be used for primary and secondary cells ( because does not need charging/discharging cycles in order to report SOC, but rather the IC can  report SOC after only 2 seconds of running ,based on battery model internal tables, previously configured) 

1. Can I power STC3117 from a buck-boost converter  fed the by cell which SOC I want STC3117 to measure ? 

This is needed mostly for primary battery scenario. The primary cell has end of discharge voltage  at 2,5 V; but STC3117 minimum supply voltage is 2,7 V. 

2. STC3117  supply current is 40uA in voltage only mode, and 80uA in mixed mode (voltage + current). What is the error between these modes ? 

[RhSilicon]

I researched about this to implement in my project.

Perhaps a way to be sure of the characteristics of the battery is to use a battery that already has a built-in controller, such as the iPhone 5s battery, etc. See this code:

https://github.com/mozzwald/hdq-batt-status/tree/master

[Pavel A.]

You can make your battery assemblies with one of those fuel gauge chips.

Calibrate them individually, or apply pre-calculated average for a batch (see the TI docum if  you choose the TI's).