BQ40Z50-R2: Min/Max RSOC for cell balancing

Hi Jonathan,

The description for each of these registers can be found in section 14.4.12 of the bq40z50 TRM:

https://www.ti.com/lit/pdf/sluubc1

1) The minimum RSOC for Balancing is just a check to ensure the pack is not in a depleted state before cell balancing, so there is no need for a maximum value for this. Below is the process of checks the gauge makes during cell balancing.

2) If the RSOC is less then the Min RSOC for Balancing, then the gauge will exit cell balancing.

Regards,

Anthony Baldino

HI Anthony,

1a. Is there a more descriptive format of the flow chart ,so it can facilitate understanding for me as there's lots of jargon?? :)

1b. interesting information which actually sounds right from a design perspective as the pack should not have a max RSOC for balancing!!!

but as per our supplier they said Max RSOC for balancing is 95%

so basically from 20%~95% that's when the balancing would occur if all condition are met 

1c. you previously mentioned Cell balancing during relax mode ,and relax mode is defined as the time after charging or discharging that the gauge enables cell balancing

What's cell balancing during Rest :)

2. so below 20% Cell balancing will never occur?

Thank you so much for bearing with me and answering so many of my questions!!!

Regards

Jonathan Kabangu

Hi Jonathan,

1. I do not believe that there is a more descriptive flow chart, however I have added annotations to the chart above to provide more simplicity. Please let me know if more detail is needed. 

"Cell Balancing at Rest" is the setting that needs to be set to allow the gauge to cell balance during relax. Rest is typically the period in relax where the cells are in a truly relaxed state. This is determined by the dV/dt condition being met.

2. Correct. If the RSOC is below 20%, then the gauge will not conduct cell balancing.

Regards,

Anthony Baldino

Hi Anthony,

1.This is brilliant!!,i will expand on each block further :)

• is the "Dv/Dt" the different in cell voltage over time ? if not what does it define?

• what's a typical timer for cell balancing in others words how long do they need to spend in balancing for optimum pack performance , does this depend on the calculation and setting computed during relax ?
• "enable balance path for those cells with balance timer >0 "does each cell have each timer ? & why does this timer need to be greater than 0?

2.

• "has an OCV measure been taken",Why are we measuring for Over cell voltage in this stage?
• "max-min (cell voltage 1....4)>Min start balance delta?"what does part define?

3.Cell balance at rest can be define as the cell balancing process once pack has entered relax and it's fully taking calculations?

Regards

Jonathan Kabangu

Hi Jonathan,

Jonathan Tshimama-Kabangu said:

is the "Dv/Dt" the different in cell voltage over time ? if not what does it define?

The dV/dt condition is the way the gauge determines if the cell is truly in a relaxed state. The condition is that the measured cell voltage cannot change by more then 4uV/s, to which I believe can be seen by the REST bit. I believe if this bit is set then the cell has cleared the condition.

Jonathan Tshimama-Kabangu said:

• what's a typical timer for cell balancing in others words how long do they need to spend in balancing for optimum pack performance , does this depend on the calculation and setting computed during relax ?
• "enable balance path for those cells with balance timer >0 "does each cell have each timer ? & why does this timer need to be greater than 0?

I do not believe there is a number for the typical timer since it relies on the cell voltage, however the formula to calculate this can be found below:

The balance times are grouped for cell 1 and cell 2-4, and if that timer number is greater then 0, then the cell balancing path will open for that cell. Each cell will have an individual balancing path. The timer basically determines whether the cell needs to be balanced and for how long.

Jonathan Tshimama-Kabangu said:

• "has an OCV measure been taken",Why are we measuring for Over cell voltage in this stage?
• "max-min (cell voltage 1....4)>Min start balance delta?"what does part define?

3.Cell balance at rest can be define as the cell balancing process once pack has entered relax and it's fully taking calculations?

OCV in this case stands for Open Current Voltage measurement, where the majority of our measurements for calculations take place. The max-min (cell voltage 1...4) > Min start balance delta is there to confirm that there is enough of a difference in the voltage between the individual cells for cell balancing to start.

3. That is correct.

Regards,

Anthony Baldino

Hi Anthony,

1. if Dv/Dt is <4uv/s indicates that it's a in true relaxed state, this means the pack will have be at Rest for this ,the only way you can achieve that level of small change in voltage over a second is if you're battery is not charging or discharging?
2. not sure if they're related but OCV=Dv/Dt=<-4uV/s, this is to confirm system is in relax once again ,correct??
3. what does the delta between the cells voltages have to be to begin balancing, what's the min and max values ?

Regards

Jonathan Kabangu

Hi Jonathan,

1. That is correct. For this to be achieved there should not be any current being applied to the cell.

2. They are roughly related. The OCV measurements are the measurements taken by the gauge to preform calculations to create values such as FCC, SOC, etc however the gauge will not take these measurements until the cell is in a truly relaxed state, where the dV/dt is less then 4uV/s.

3. The delta value to begin balancing is checking the largest cell voltage in the cell stack, the lowest cell voltage in the cell stack, and subtracting them to see if the difference between the two of them is large enough to begin cell balancing. 

Regards,

Anthony Baldino

Hi Anthony,

1. That is correct. For this to be achieved there should not be any current being applied to the cell.

JK:no current being applied or drained from cell, in our system we're always pulling current(discharge) or applying current(charging) the pack is never at rest at one time inside the unit!!

is this an issue long term on the performance of the pack?

2. They are roughly related. The OCV measurements are the measurements taken by the gauge to preform calculations to create values such as FCC, SOC, etc however the gauge will not take these measurements until the cell is in a truly relaxed state, where the dV/dt is less then 4uV/s.

JK:in the case of entering relax to enable balancing, this is only looking at the Dv/dt=4uV/s which is at rest ?

is this 4uV/s for the pack voltage or per cell?

Regards

Jonathan Kabangu

Hi Jonathan,

Jonathan Tshimama-Kabangu said:

JK:no current being applied or drained from cell, in our system we're always pulling current(discharge) or applying current(charging) the pack is never at rest at one time inside the unit!!

is this an issue long term on the performance of the pack?

Yes, this could potentially be an issue for the long term performance of the pack. There does not need to be a relax period after every charge or discharge, however if an extended period goes by without a relax period there error can build up and there can be issues with the calculations.

Jonathan Tshimama-Kabangu said:

JK:in the case of entering relax to enable balancing, this is only looking at the Dv/dt=4uV/s which is at rest ?

is this 4uV/s for the pack voltage or per cell?

There are other factors that the gauge will look at once rest is entered, however the initial condition to enter relax is clearing the dV/dt condition. I believe this is based on the pack voltage, however I will confirm this with our team.

Regards,

Anthony Baldino

Hi Anthony,

1.Yes, this could potentially be an issue for the long term performance of the pack. There does not need to be a relax period after every charge or discharge, however if an extended period goes by without a relax period there error can build up and there can be issues with the calculations.

JK:our pack is most probably imbalanced due the nature of our system always discharging/charging and it never gets rest time ,this imbalance is further causing delta in cells and causing one cells to be higher than the other thus reaching max voltage before the others ,therefore pack caps <100% or it's showing improper RSOC due to not taking proper calculation for OCV?

look example:

2.There are other factors that the gauge will look at once rest is entered, however the initial condition to enter relax is clearing the dV/dt condition. I believe this is based on the pack voltage, however I will confirm this with our team

Jk:please do let me know once confirmed with the team

JK:OCV:open current voltage, this is needed to update FCC, RSOC is there a defined number or value for this setting/parameter?,without relax mode ,OCV measurement won't be taken therefore improper FCC,RSOC?

JK:please any suggestion is welcome on how we can make our system to enter relax mode without disrupting it's operation (by taking it our the hub/device to give it rest time)

Regards

Jonathan Kabangu

Hi Jonathan,

Jonathan Tshimama-Kabangu said:

JK:our pack is most probably imbalanced due the nature of our system always discharging/charging and it never gets rest time ,this imbalance is further causing delta in cells and causing one cells to be higher than the other thus reaching max voltage before the others ,therefore pack caps <100% or it's showing improper RSOC due to not taking proper calculation for OCV?

It is possible that it is showing the improper RSOC because there is no time for the OCV measurement.

Jonathan Tshimama-Kabangu said:

OCV:open current voltage, this is needed to update FCC, RSOC is there a defined number or value for this setting/parameter?,without relax mode ,OCV measurement won't be taken therefore improper FCC,RSOC?

JK:please any suggestion is welcome on how we can make our system to enter relax mode without disrupting it's operation (by taking it our the hub/device to give it rest time)

This is correct. However, there is no defined value for FCC and RSOC parameter. The main issue with there being no OCV measurement is that over time as the true FCC of the gauge changes, this will not be reflected in the measurements since there is no calculation or time to update it.

In this system, I am not sure if there is a possible way for relax to be entered due to the constant charge or discharge, and the measurements and calculations relying on a fully relaxed cell with a period of time of no charge or discharge.

Regards,

Anthony Baldino

Hi Anthony,

1.I had a question in regards to the bits flags being raised in BQstudio

logically we know 1=True/ON & 0=false/OFF

in BQstudio there's the colour RED & GREEN

Which one represents ON and which one represents OFF?

2. 

What's the difference between CB&CB_EN bits?

OCVFR=open circuit voltage flat region:what does this mean 

SO in this case since they're RED that means it's ENABLED???

Here's a Screenshot for ref:

3.currently our Min RSOC for balancing is 20%

• Can we lowered this value let's say down to 5% and what will happen if we do change this value?

Regards

Jonathan Kabangu

Hi Jonathan,

Jonathan Tshimama-Kabangu said:

1.I had a question in regards to the bits flags being raised in BQstudio

logically we know 1=True/ON & 0=false/OFF

in BQstudio there's the colour RED & GREEN

Which one represents ON and which one represents OFF?

Red = 1/ON

Green = 0/OFF

Jonathan Tshimama-Kabangu said:

What's the difference between CB&CB_EN bits?

OCVFR=open circuit voltage flat region:what does this mean 

SO in this case since they're RED that means it's ENABLED???

Here's a Screenshot for ref:

BAL_EN means that at that moment in time, cell balancing is possible, however it does not mean whether cell balancing is actively occurring. CB means whether cell balancing is actively occurring or not (active = 1).

The meaning of OCVFR can be found below:

Jonathan Tshimama-Kabangu said:

Can we lowered this value let's say down to 5% and what will happen if we do change this value?

Min RSOC for Balancing refers to what the minimum RSOC value needs to be before balancing can occur. This value can be set to whenever you want cell balancing to begin, including 5%.

Regards,

Anthony Baldino

Hi Anthony,

1.that paragraph does not define what's OCVFR is, i even clicked on the "SLUA372" link it does not quite expand on it,can you help out on this please :)

in simplicity is an "open circuit voltage flat region" a good thing or bad

2.Min RSOC for Balancing refers to what the minimum RSOC value needs to be before balancing can occur. This value can be set to whenever you want cell balancing to begin, including 5%.

JK:our battery vendor told us the reason this is at 20% is because cell balancing process drains the battery capacity so setting it at 20% was a safe bet rather than 10% or 5% ,is this accurate?

Regards

Jonathan Kabangu

Hi Jonathan,

Jonathan Tshimama-Kabangu said:

1.that paragraph does not define what's OCVFR is, i even clicked on the "SLUA372" link it does not quite expand on it,can you help out on this please :)

in simplicity is an "open circuit voltage flat region" a good thing or bad

Being within the OCVFR is not a good thing, since when the gauge begins to take OCV measurements to update the Qmax parameter of the gauge, these measurements and calculations will be invalidated if the measured voltage is within this region. Where this region is based on the chemID being used. When the cell is at rest, this region should be avoided.

Jonathan Tshimama-Kabangu said:

our battery vendor told us the reason this is at 20% is because cell balancing process drains the battery capacity so setting it at 20% was a safe bet rather than 10% or 5% ,is this accurate?

This is correct. Having the parameter at 20% can protect the individual cells from becoming too low.

Regards,

Anthony Baldino

Hi Anthony,

1.Being within the OCVFR is not a good thing, since when the gauge begins to take OCV measurements to update the Qmax parameter of the gauge, these measurements and calculations will be invalidated if the measured voltage is within this region. Where this region is based on the chemID being used. When the cell is at rest, this region should be avoided.

JK:how do we avoid being in this flat region?

is there any numerical value to watch out for that can indicate if we're in this region?

2.

in the screenshot above the CB,CB_EN & REST flags are all 1/ON

2A. how's cell balancing possible whilst charging 

2B. When Pack is charging this is not longer in rest ? so how come the REST flag is raised 

Regards

Jonathan Kabangu

Hello Jonathan,

Anthony will be out of town for a while, but I can continue to support you.

Jonathan Tshimama-Kabangu said:

JK:how do we avoid being in this flat region?

To help answer this, can you tell me more about the typical application you will be using. Maybe even sharing a load profile that might be typical for your system.

Jonathan Tshimama-Kabangu said:

is there any numerical value to watch out for that can indicate if we're in this region?

This depends greatly on the specific battery and chemistry. 

Jonathan Tshimama-Kabangu said:

2A. how's cell balancing possible whilst charging 

Please read this documentation to learn more about this: https://www.ti.com/lit/an/slva155/slva155.pdf

Jonathan Tshimama-Kabangu said:

2B. When Pack is charging this is not longer in rest ? so how come the REST flag is raised 

Can you send me a log file of this occurring? Can you also send me the gg file for the gauge?

Regards,

Nick Richards

HI Nick,

1.NR:To help answer this, can you tell me more about the typical application you will be using. Maybe even sharing a load profile that might be typical for your system.

• JK:in terms of application our device lies inside a hub and delivers power to an internal security device inside a car and pulls a max current of 400~450mA
• there's also a sleep mode of about 20~30mA until it detects an event then it goes up 450mA
• I will try to get a load profile for you 

2.if you can get information and details on flat region values for Lifepo cells that will be appreciated

3.another issue occurred whilst i tried getting the log for you ,the pack stopped charging and the pack enabled "COV" and stopped charging at 94%

i'm guessing cell 3 hit COV ,i'd like to understand the root cause it was simply in charge then this happened

furthermore how did this happen as CB & CB_EN is enabled meaning it's balancing cells but the

log file:

NL-02.log

gg file:

nl02gg.gg.csv

Regards

Jonathan Kabangu

Hello Jonathan,

Jonathan Tshimama-Kabangu said:

• there's also a sleep mode of about 20~30mA until it detects an event then it goes up 450mA
• I will try to get a load profile for you 

I took a look at your gg file and I think the dsg current threshold should be set lower to account for the sleep mode current of between 20-30mA. Right now the Dsg current threshold is set to 100mA and I think it will be best if that is set below 20mA. So maybe around 15mA. 

Jonathan Tshimama-Kabangu said:

if you can get information and details on flat region values for Lifepo cells that will be appreciated

I can not share specific voltage values of the flat region however I can share some knowledge in terms of estimating the flat region. LFP chemistry is much more difficult because it has a larger flat region compared to other chemistries. 

This is an example graph of the discharge profile for an LFP battery and the red lines is what I would consider to be an approximation of the flat region. 

The gauge implements passive cell balancing and it takes a while for the cells to become balanced since it uses very small current to balance the cells. If you want the cells to balance faster, then you will need to implement an active cell balancing circuit.

Regards,

Nick Richards

Hi Nick/Anthony,

sorry for the delayed response ,been out of town for a few days

1. as for the CHG/DSCH current thresholds ,are these the points to which charging is triggered ?, e.g when charging input is applied to pack as soon as as it sees current let's say 15mA for a certain amount then Pack will enter charge mode?,similarly for discharge if it sees 15mA for a certain period then it will enter discharging mode ?
2. how do we better control the Flat region so our pack never enters this section whilst taking measurements?
3. when one of the cells hit COV does it recover itself ?
4. when COV occurs is this due to imbalance in cells since one of the cells has it's maximum first ?
5. what's the difference between Passive & active balancing in layman's term

hope to hear from you soon

Regards

Jonathan Kabangu

Hi Jonathan,

Jonathan Tshimama-Kabangu said:

as for the CHG/DSCH current thresholds ,are these the points to which charging is triggered ?, e.g when charging input is applied to pack as soon as as it sees current let's say 15mA for a certain amount then Pack will enter charge mode?,similarly for discharge if it sees 15mA for a certain period then it will enter discharging mode ?

When either the CHG or DSG Threshold is passed, the gauge will enter the respective mode for the current being seen. This is measured across the sense resistor over a 1s period, meaning the average current over the one second period must break the threshold. The gauge will automatically enter the respective mode after this is seen.

Jonathan Tshimama-Kabangu said:

how do we better control the Flat region so our pack never enters this section whilst taking measurements?

The flat region is not something that can be altered, since it is defined by the chemID being used with the gauge. 

Jonathan Tshimama-Kabangu said:

when one of the cells hit COV does it recover itself ?

If COV is triggered, the gauge will recover if the conditions below are met:

Jonathan Tshimama-Kabangu said:

what's the difference between Passive & active balancing in layman's term

Passive cell balancing dissipates charge throughout the charge cycle, while active cell balancing redistributes the charge during the charge cycle.

Regards,

Anthony Baldino

Hi Anthony,

it's set at 3750mV ,the recovery setting is implemented at 3500mV

Question:See screenshot:

gg file:01GU.gg.csv

gg file:006k.gg.csv

:Why's the COV triggering at 100%

• i heard active balancing is much better and faster than passive ?

Regards

Jonathan Kabangu

Hi Jonathan,

I believe the COV protection is not clearing due to the Cell 3 voltage being higher then the recovery threshold. Also, I cannot pin point where the COV protection was triggered without a log file, however there could of been a moment where the COV protection threshold was passed by one of the cells.

I believe that active balancing is more effective then passive.

Regards,

Anthony Baldino

Hi Anthony,

if you look at the screenshot ,this flag seems to raising after pack has reached 100%,any reason why?

i will provide logs for this pack tomorrow so we can deep dive it further

i will look into active balancing method and it's advantages 

Regards

Jonathan Kabangu

Hi Jonathan,

Jonathan Tshimama-Kabangu said:

if you look at the screenshot ,this flag seems to raising after pack has reached 100%,any reason why?

I believe the log file will give us better insight into why this is potentially occurring within the gauge.

Regards,

Anthony Baldino

Hi Anthony,

I've been trying to reproduce cause the same pack no longer shows this COV bit

from the Screenshot it looks cell 3 went above the COV Theshold

My question:

once pack has reached 100% ,no cells should be topped up further i'm interested as to why this reached 3750mV> at 100% or after

Regards

Jonathan Kabangu

Hi Jonathan,

When Valid Charge Termination is reached, the gauge's charging algorithm will change to the maintenance charge, which should keep the voltage of the device at the same place, but it will not stop charge all together. If possible, can you see what the charge current was once 100% was reached?

Regards,

Anthony Baldino

Hi Anthony,

somehow i forgot to attach the screenshots and logs so we can analyse this 

logs:0037 (1).log

if you look at the logs and values above the current is at about 892mA at 100%,this then pushed then cells to go above COV, this tells me that the charge termination did not kick in to reject charging once 100% was reached any reason why 

Regards

Jonathan Kabangu

Hi Jonathan,

I believe that since for valid charge termination needs to be met for 2 consecutive 40 second periods, the sudden jump in voltage from 13700 to 14000+ is causing the COV protection to go off since the timing was not met to meet valid charge termination and the voltage went right past it.

Regards,

Anthony Baldino

Hi Anthony,

Charge term voltage :100mV

what does this mean and how do i watch out for it if it's met or not?

Regards

Jonathan Kabangu

Hi Jonathan,

The charge term voltage is used to meet the condition below, where it is added to the maximum cell voltage then compared to the charging voltage. If this condition along with the other conditions below are met for 2 consecutive 40 second periods, then the [VCT] bit will become set.

Regards,

Anthony Baldino

Hi Anthony,

Just to confirm ,is the charge term voltage something we can see in the BQstudio registers in real time like the avg current, remaining capacity ?

Regards

Jonathan Kabangu

Hi Jonathan,

The Charge Term Voltage is a settable parameter that can be found in the Data Memory section of bqStudio. This parameter is static and should not move during the functioning time of the gauge.

Regards,

Anthony Baldino

Hi Anthony,

can you help out with this please,FC & TC are not being set despite our Pack meeting the conditions(3500mv,100%)

i've attached logs,screenshot and gg file of the pack

6332.01NL.log

2112.01NL.gg.csv

Regards

Jonathan Kabangu

Hi Jonathan,

In your SOC Flag Config A and SOC Flag Config B, you have FC and TC to set upon valid charge termination. These parameters can be changed in the registers below:

Regards,

Anthony Baldino

Hi Anthony,

How were you able to figure that information out?

cause all i can see in the gg file is this 

can you breakdown what the hex codes mean please

Regard

Jonathan Kabangu

Hi Jonathan,

To understand the bits within the register, convert the value from hex to binary:

8C -> 10001100

Regards,

Anthony Baldino

Hi Anthony,

I will play about with these settings and update you 

Regards

Jonathan Kabangu

Hi Jonathan,

Understood, please let us know if there is any improvement in performance.

Regards,

Anthony Baldino

Hi Anthony,

Question 1: For FC or TC to be set do we need to meet ALL conditions set in the gg file or if we meet one of them the bit will set?

example for FC:

for this to be TRUE(FC=1) ,does voltages of all cells have to be above 3.5V AND RSOC @ 100% or if we meet one of the two conditions then this will be TRUE

Example for TC:

for this to be TRUE(TC=1) ,does voltages of all cells have to be above 3.5V AND RSOC @ 100% or if we meet one of the two conditions then this will be TRUE

Question 2:

1. Although Reached 100% ,VCT ,FC or TC is NOT SET?
2. do all cells have meet the FC,FC threshold at 3.5V for it to be set to 1?
3. does COV play a part here on not seeing these bits turning ON?
   
4. the gauge seems to be balancing by the indication of CB,CB_EN flags but the DSG flag is also ON which indicates the system is discharging ,and from my understanding Cell balancing does not occur during discharge so how is this possible?

Regards

Jonathan Kabangu

Hi Jonathan,

Jonathan Tshimama-Kabangu said:

Question 1: For FC or TC to be set do we need to meet ALL conditions set in the gg file or if we meet one of them the bit will set?

example for FC:

for this to be TRUE(FC=1) ,does voltages of all cells have to be above 3.5V AND RSOC @ 100% or if we meet one of the two conditions then this will be TRUE

Example for TC:

for this to be TRUE(TC=1) ,does voltages of all cells have to be above 3.5V AND RSOC @ 100% or if we meet one of the two conditions then this will be TRUE

I believe that meeting just one of the thresholds should set the FC or TC bit.

Jonathan Tshimama-Kabangu said:

Although Reached 100% ,VCT ,FC or TC is NOT SET?

I would need a log file to look deeper into what is occurring here,

Jonathan Tshimama-Kabangu said:

do all cells have meet the FC,FC threshold at 3.5V for it to be set to 1?

Just the Maximum Cell Voltage from the stack has to meet the threshold for the FC bit to be set.

Jonathan Tshimama-Kabangu said:

does COV play a part here on not seeing these bits turning ON?

Potentially, I would need to see the log file to understand what is going on here deeper. Looking at the TRM, the COV protection only alters the [TCA] bit out of the ones above.

Jonathan Tshimama-Kabangu said:

the gauge seems to be balancing by the indication of CB,CB_EN flags but the DSG flag is also ON which indicates the system is discharging ,and from my understanding Cell balancing does not occur during discharge so how is this possible?

The DSG bit reflects when the gauge is in discharge or relax. Cell Balancing can occur in relax mode.

Regards,

Anthony Baldino

Hi Anthony,

You mentioned "In your SOC Flag Config A and SOC Flag Config B, you have FC and TC to set upon valid charge termination. These parameters can be changed in the registers below:"

JK: Does this mean that the TC and FC flags are tied to VCT, in other words for TC and FC it will only be set if VCT is TRUE, is this correct?

JK:is this the setting that's implemented on our gauge?

JK:not sure if you've already defined this but was wondering how were you able to figure out that our setting is TC & FC were TRUE upon VCT=1,

all the GG file says is:

SOC flag Config A:0c8c

SOC flag Config B:8c

JK: Wanted to Breakdown the conditions for VCT further, correct me if my statement is wrong!!

All of the following conditions must occur for

two consecutive 40-s periods:

Charging (that is, BatteryStatus[DSG] = 0) :Battery has to be in charge mode

AND

AverageCurrent() < Charge Term Taper: The average current that is the charge current has to be less than the termination current 

Current AND

Max cell voltage1..4 + Charge Term

Voltage ≥ ChargingVoltage() / number of: the voltages of the cells combined plus the termination voltage has to be greater the charging voltage divided by the number of cells in series 

cells in series AND

The accumulated change in capacity >: i'm not too sure about this one ,can you explain it please?

0.25 mAh

Regards

Jonathan Kabangu

Hi Jonathan,

Jonathan Tshimama-Kabangu said:

JK: Does this mean that the TC and FC flags are tied to VCT, in other words for TC and FC it will only be set if VCT is TRUE, is this correct?

If [TCsetVCT] and [FCsetVCT] are set in the SOC Flag Config A, then this will rely on VCT being true.

Jonathan Tshimama-Kabangu said:

not sure if you've already defined this but was wondering how were you able to figure out that our setting is TC & FC were TRUE upon VCT=1,

The gg file tells the register value in a hexadecimal value. To find the settings, convert the value to binary and compare with the mapping for the register in the TRM.

0C8C -> 1100 1000 1100

Jonathan Tshimama-Kabangu said:

The accumulated change in capacity >: i'm not too sure about this one ,can you explain it please?

Your understanding is correct. The accumulated change in capacity means that the amount of passed charge within the period cannot exceed 0.25mAh. This means that the current needs to be low enough to not break this condition.

Regards,

Anthony Baldino

Hi Anthony,

"The gg file tells the register value in a hexadecimal value. To find the settings, convert the value to binary and compare with the mapping for the register in the TRM."

0C8C -> 1100 1000 1100

JK: What is the TRM, so i can compare those binary values against it ???

Regards

Jonathan Kabangu

Hi Jonathan,

The TRM is the bit mapping of the register. They can be compared like below:

0C8C -> 1100 1000 1100

The red box correlates to a 1, meaning that bit is set.

Regards,

Anthony Baldino

Hi Anthony,

i get that part but i'm still a little bit confused on how 0c8c--> 1100 1000 1100 corresponds to TCSETVCT,FCSETVCT etc...

it does not show on the Datasheet document how that hexcode translates to those bits 

TCSETVCT=11

FCSETVCT=10

TCCLEARRSOC=7

TDCLEARRSOC=3

TDSETRSOC=2

hope you do not mind breaking this down further

Regards

Jonathan Kabangu

Hi Jonathan,

Please let me know if this helps:

The Technical Reference Manual can be found here: https://www.ti.com/lit/pdf/sluubk0 

The bits directly correlate to the binary translation of the hex value.

Regards,

Anthony Baldino

Hi Anthony,

Just back on this topic 

For VCT condition to be met i believe there's several condition that needs to be met ,

as seen here

• Do we know how long in practice this may take to set VCT?
• For our Pack the LED goes solid at 100% to indicate 100% but then the LED stays solid until the VCT conditions are met then it goes OFF,in other words the charge termination in our pack is linked to our LED,that's why i asked how long can this VCT condition take so it can be set?

Regards

Jonathan Kabangu

Hi Jonathan,

Jonathan Tshimama-Kabangu said:

Do we know how long in practice this may take to set VCT?

At minimum, it will take 80 seconds due to two different 40s periods. It could take longer if any of the conditions are not met during this time.

Jonathan Tshimama-Kabangu said:

For our Pack the LED goes solid at 100% to indicate 100% but then the LED stays solid until the VCT conditions are met then it goes OFF,in other words the charge termination in our pack is linked to our LED,that's why i asked how long can this VCT condition take so it can be set?

Understood, is it being seen that this process is taking an extended amount of time to complete?

Regards,

Anthony

HI Anthony,

80 seconds minimum as per the documentation ! but this is not the case for our pack, did testing around this the longest it took was 20 minutes and the quickest time was 2 minutes ,any reason why this is happening 

i'll share with you the test report

i'll also share with you the log for the for pack that took the 

FE002FJ00263240005Z-01:this pack met the condition the fastest

005Z-01.log

FE002FJ002632400AN-01:this pack took the longest:

00AN-01.log

FE002FJ002634301NL-02:this took 4 minutes

01NL-01.log

FE002FJ00263170005-01:this pack took 10 minutes

0050-01.log

Can you have a look at the logs and please help me understand why they all have different timing for VCT Setting 

Regards

Jonathan Kabangu