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BQ40Z50: Algorithm

VICTOR VICTOR
Intellectual 290 points
Part Number: BQ40Z50
Other Parts Discussed in Thread: GPCRB

Hello, After reading the technical reference and SLUA364B i have some questions :

1) the technical ref say that once in RELAX mode , OCV is taken after :


A dv/dt condition
B five hours of Current condition
C) upon reset
D Enable commmand

on the other side, slua364b say that OCV readings are taken after 30 minute relaxation period has passed then ocv readings continie to be taken every 100 sec. 

how can i solve this misunderstanding?

2)The resistance is calculated using the next formula :


R(DOD)=dv/i

where dv=V-OCV(DOD,T)

in order to calculate OCV(DOD,T) according to the technical reference the device should be on RELAX mode on each point of DOD to calculate the OCV(DOD,T).

but during the Learning Cycle there is a continuous charge and discharge , so how do we get these OCV(DOD,T) ?


3) the calculation of Remaining capcity is executed using different methods . can you please reconcile the contradiction?

on the one way , it is written that the Remaining capacity is calculated using Simulation( of V(DODx,T)=OCV(DODx,T)+IxR(TOTx,T)....)  and is taked place after each resistnce grid point update.

on the other hand  it is written that Remaining capaicty is continuously (every 1 second) updated based on the integrated Charge .


4)  can you please elaborate the meaning of " Q START "

5) what is the motivation to update the temperature model ? for example if the CV curve is changed during discharge under Some temperature so the gas gauge change the coefficients of the Deafult chemistry file ?
6) is there any register which implies that the stack is balanced?

7) is there any register which represent te version of the srec file?

8) on the SLUSCB3 . page 28 there is an application scheme.

if i disconnect R12 and conect Pack to the ground,  Will it damage the device ? will Q2 not conduct?( of course i am not speaking about the suggested operation..)

as i understand the power supply control of figure 1 from page 5 of SLUSCB3 , if the PACK is connected to ground . the pack detector disable the connection of VCC and BAT to supply the Gas gauge controller . am i correct ?


thank you for you help 

  • 0
    TI__Mastermind 42535 points

    1. OCV readings are taken after 5 hours in relaxation.

    2. Readings are taken by the gauge based on grid points referenced from the DOD. It's not an OCV reading during dsg but a measurement of Ra at the grid points. Also, these are not actual readings but calculations based on your load select to determine the load used to calculate RSOC

    3. Reported remcap is based on coulomb counting which is augmented by IT simulations done using the value of Remcap adjusted at grid points based on load select used for IT simulations.

    4. Qstart is basically the charge available during start of chg or dsg at any particular state.

    5. Because you want the gauge to be accurate across temps and not at a particular temperature. This is why we have GPCRb tool as well which allows you to characterize for temperature as well.

    6. Yes, CB registers in OperationStatus

    7. No, but you can check fw version by command 0x0002.

    8. Yes, if you don't have the reverse charger connection as shown by Q4, you can damage the device.