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STC3117 Fuel Gauge not entering CC mode when discharging, but does enter CC mode when charging. Why would the fuel gauge work for charging, but not for discharging?

TTIED.1
Associate

Hello,

I have a custom board with a STC3117 as the fuel gauge to a 5200mAh lithium ion battery pack. The pack can charge up to 1.5A and discharge to up to 3 A.

The issue I am seeing is that the SOC will be stable with the system running. When I charge the battery, the SOC gradually increases even though there is a voltage increase due to charging. This indicates I am in CC mode and not following the OCV curve while in the voltage monitoring mode.

When I discharge the battery at 2.5A, we see the voltage drop due to the high current pulling the battery voltage down. However, the SOC does not gradually decrease, it jumps down which appears to follow the OCV curve. This would indicate to me, that the device is using the voltage mode. This jump happens within 4 seconds (so basically after the next round of measurements done by the STC3117). When I unplug the charger it jumps back up again, voltage and SOC. I don't want to have to implement a new monitoring function that will force the fuel gauge into CC mode and then back to voltage mode based on charging and discharging.

Any help would be appreciated.

Thanks,

Tyler

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