Hi All,

I have a question that might be trivial, and I'd appreciate some advice on the correct method to handle it.

I’ve been using lithium-ion batteries with voltages of both 12.6V and 4.2V. The 12.6V battery has 3 sets of cells.

The battery pack also includes a protection circuit, which I believe regulates charging against overvoltage, undervoltage, high current, and temperature.

One issue I’ve noticed is that when the battery is fully drained, the voltage drops to a very low level, such as 2.7V. When you recharge the battery, the charging IC enters a preconditioning mode where it outputs a maximum of around 10mA. However, if you have other circuits or LEDs running, this 10mA is also consumed, preventing the battery from progressing past the preconditioning stage due to the voltage remaining very low.

I understand that I could use an ADC to monitor the battery in the microcontroller, and if the voltage reaches a certain level (e.g., 3V), I could switch off the entire circuit. However, I would then need to read the ADC values at intervals to check if the voltage has started to increase.

Is it possible to implement this logic using hardware alone?

My Li-ion charger IC is the LTC4162.

 

I assume the controller is talking to the charger IC so you already have access to battery voltage.

https://www.analog.com/media/en/technical-documentation/data-sheets/LTC4162-L.pdf
16-Bit Digital Telemetry System Monitors VBAT, IBAT, RBAT, TBAT, TDIE, VIN, IIN, VOUT

vbat 0x3A R [15:0] 0 Signed number that indicates the A/D measurement for the per-cell battery voltage. The value is based on the A/D scaling factor for the battery voltage measurement which is cell_count × 192.4µV/LSB at the BATSENS+ pin.

 

Well, the battery voltage values only works if there is power at VIN, but if there is no power at VIN, it simply outputs the last known value.

 

Certainly a hardware only voltage monitor scheme is available. That would be a comparator and a few resistors. But it may require a separate power supply.