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BQ2060: Low-power storage mode queries

Amirul Kamaruzaman
Prodigy 80 points
Part Number: BQ2060
Other Parts Discussed in Thread: BQ41Z50, BQ40Z50

Tool/software:

Hello,

I have few questions regarding the BQ2060 Low-power storage mode.

1. During low-power storage mode, does self-discharge rate also not functioning?

2. What will happen after wakeup from low power storage mode? Will the stored value in registers recover back to what it was before the low-power storage mode initiated? Full list of registers that I am using are:


RemainingCapacityAlarm 0x01 
BatteryMode 0x03 
Temperature 0x08 
Voltage 0x09 
Current 0x0a 
AverageCurrent 0x0b 
MaxError 0x0c 
RelativeStateOfCharge 0x0d
AbsoluteStateOfCharge 0x0e 
RemainingCapacity 0x0f 
FullChargeCapacity 0x10 
ChargingCurrent 0x14 
ChargingVoltage 0x15 
BatteryStatus 0x16
CycleCount 0x17 
DesignCapacity 0x18
DesignVoltage 0x19 
ManufactureDate 0x1b 
SerialNumber 0x1c 
CustomData2f 0x2f 
CustomData3c 0x3c 
CustomData3d 0x3d
CustomData3e 0x3e 
CustomData3f 0x3f 

3. If the registers above are reset to default value / random values, will it be mandatory to recalibrate after waking up?

4.For the CFC and DFC Pin, are they both will be OFF during low power storage mode? 

5. Is the Max Error reset to 100% after waking up?

 

If you have other drop in alternative for BQ2060, please also advice that I can try to look at. But so far, I see the part is still active - please let me know if there is a plan to obsolete this.

Thank you in advance, look forward for your replies.

Best Regards,

Amirul

  • +1
    TI__Mastermind 27321 points

    Hello,

    1- The BQ2060 stops tracking self-discharge during this mode (no active updates), but the battery’s physical self-discharge continues. Tracking resumes upon wakeup, estimating the loss based on stored parameters.
    2- Static registers (e.g., DesignCapacity, SerialNumber) stored in EEPROM recover their pre-sleep values. Dynamic registers (e.g., Voltage, Current, RemainingCapacity) update to reflect the current battery state, not pre-sleep values.
    3- If registers reset to default/random values (e.g., due to a power loss), recalibration is mandatory for accuracy. Under normal wakeup, EEPROM data prevents this, and recalibration isn’t required unless the battery state has significantly changed.
    4- Both CFC (Charge FET Control) and DFC (Discharge FET Control) pins are likely OFF during low-power storage mode to conserve power and isolate the battery, resuming normal operation upon wakeup.
    5- MaxError retains its pre-sleep value upon wakeup, not resetting to 100%, unless a full reset occurs or significant capacity errors are detected post-sleep.
  • 0 in reply to Jose Couso
    Prodigy 80 points

    Hi Jose,

    Thank you for the answers, but for point no. 3 I wish to get more clarification on this statement "recalibration isn’t required unless the battery state has significantly changed."

    1. What do you mean by battery state has significantly changed? Is it changed in RM / FCC or any other changes that affect this?

    2. If you were to quantify "significantly changed", what would be the number? For the 2 scenarios below, are they consider significant changes and require recalibration?

            a) In the case of the SOC pre-sleep is 70% and after wakeup is 50%.

            b) In the case of 1 year to 2 years sleep duration. (Cell degradation over the years could play an impact?)

    3. Would the BMS IC automatically raise the RELEARN_FLAG upon detecting this significant change? From the datasheet in normal mode relearn flag only raised in the case of full reset or 20 cycle counts without FCC update.

    Best Regards,

    Amirul

  • 0 in reply to Amirul Kamaruzaman
    TI__Mastermind 26135 points

    Hello Amirul,

    Your question is under review and being investigated into for a response.

    Thank you,
    Alan

  • +1 in reply to Amirul Kamaruzaman
    TI__Mastermind 27321 points

    Hello,

    1- A "significant change" means a mismatch between stored data (RM, FCC) and the actual battery state after wakeup, due to self-discharge, capacity fade, or aging, affecting SOC, RM, FCC, or voltage measurements.

    2- 
    a) SOC 70% to 50%: A 20% SOC drop isn’t significant unless MaxError rises sharply or high accuracy is needed; recalibration may not be required.

    b) 1–2 years sleep: Likely significant due to 10–20% capacity fade (200–400 mAh) and large SOC drop from self-discharge. Recalibration is recommended.

    3- The BQ2060 doesn’t raise the RELEARN_FLAG after wakeup, even with significant changes. It’s only set after a full reset or 20 cycles without an FCC update, per the datasheet.


  • 0 in reply to Jose Couso
    Prodigy 80 points

    Hi Jose,

    Thank you for the continuous support.

    One additional thing on the self-discharge rate - If in the scenario where the self-discharge rate was programmed as cell self-discharge + IC normal operating current and then the battery is put in sleep mode and stored for 1 year, upon wakeup would the RM reported be far off less from the actual capacity due to sleep mode current consumption is much lower? 

    If this is the case, then how may I segregate between Self discharge with IC normal operating mode & Self discharge with IC in sleep mode?

    Best Regards,

    Amirul

  • +1 in reply to Amirul Kamaruzaman
    TI__Mastermind 27321 points

    Hello,

    If the self-discharge rate is programmed for cell + normal IC current (e.g., 30% per year), but the IC uses less current in sleep mode (e.g., actual loss 25% per year), the reported RM will be ~5% lower than the actual capacity (e.g., 100 mAh for a 2000 mAh battery). This isn’t “far off” but may require correction for high-accuracy applications.

    Segregating self-discharge rates:

    1. Calculate cell self-discharge (2% per month) and IC contributions: normal mode (5.4% for 150 µA) and sleep mode (~0.54% for 15 µA).
    2. Program the BQ2060 for normal mode (e.g., 7.4% per month) and adjust RM after sleep by adding back the overestimated loss (e.g., 5% per year × sleep duration).
    3. Alternatively, program for sleep mode (2.54% per month) and adjust during normal operation, depending on your use case.
  • 0 in reply to Jose Couso
    Prodigy 80 points

    Hello Jose,

    Follow up questions as follow:

    1) Does this mean that the calculation (Option 2/Option 3) must be done externally and overwrite the RM for adjustment?

    2) Is there a register that can give us accurate total sleep time that the IC was in, or this also need to be calculated manually? Does the IC have internal RTC that continue to work during sleep mode?

    3) I was expecting the RM adjustment could be done automatically by the IC considering the voltage levels that the batteries are in. For example, a sleep battery will have significantly higher voltage compared to a normal operating battery overtime thus the RM of a sleep battery should be higher compared to the normal operating battery. My understanding is the IC surely takes consideration of the voltage levels also before computing the RM value and not fully depend on the self-discharge rate programmed, correct me if I'm wrong.

    4) It is mentioned in the datasheet that during sleep mode the IC does not perform any gas gauge functions, does this exclude self-discharge?

    5) I have an idea of overwriting the self-discharge rate before and after sleep instead of adjusting the RM after wakeup. Before each sleep I plan to program the self-discharge rate to become lower and on every wakeup to program self-discharge rate to be higher. Would this idea also work with a sealed IC? I searched thru the website and there is no option to unseal the battery (which we currently have a lot on hand >1k units).

    6) Do you have any other BMS IC with SMBus compatible that can do this RM adjustment automatically? I saw the BQ41Z50 has a feature for auto-sleep whenever the SMBD/SMBC line is off - would this newer gen BMS IC with impedance tracking also require external manual intervention to adjust the RM accurately after a long period sleep?

    Best Regards,

    Amirul

  • +1 in reply to Amirul Kamaruzaman
    TI__Mastermind 27321 points

    Hello,

    1- Yes, Options 2/3 require external calculation and overwriting of RM to correct for self-discharge rate discrepancies.

    2- No register tracks sleep time; the BQ2060 lacks an RTC. You’ll need an external timer to calculate sleep duration.

    3- The BQ2060 doesn’t adjust RM based on voltage after wakeup; it relies on the programmed self-discharge rate. Voltage influences RSOC, but RM requires manual correction.

    4- The BQ2060 doesn’t actively track self-discharge during sleep (no gas gauge functions); it applies the programmed rate retroactively upon wakeup.

    5- Your idea to adjust the self-discharge rate before/after sleep won’t work with sealed ICs, as you can’t modify the EEPROM. Adjust RM instead.

    6- The BQ40Z50 with Impedance Track can automatically adjust RM after long sleep periods using voltage and impedance, minimizing manual intervention.It is SMBus-compatible and better suited than the BQ2060 for your needs.