Battery pack Production flow With bq20z75........

Hi Kjell,

I wouldn't advice using command 21. writing command 46 word 0006 turns the fet on. After turning them on, what causes them to switch off?

Also, after creation of your golden gg file, you need to change update status from 06 to 02 before programming on other devices otherwise IT will be automatically enabled upon programming and that will  cause inaccuracies in gauging.

Try to check what causes your fets to turn off after sending command 46 word 0006. This is the right command and ought to be what is used.

thanks

Onyx

Hi Onyx,

Thanks for your support Onyx. Having this "source of information" is very much appreciated.

Our Golden DFI has the update status set to 02. We do the calibration as recommended by TI, (using powersupply and  resistors simulating the cells etc) but after that, - each PCB goes through several function tests in a test fixture (before attached to the battery cells) where several 1st Level and 2nd Level Safety parameters are tested. If we are using the 0x46 to Control the FET's we have to issue this command after each individual test which is time consuming. I think checking the different safety Level is the reason for the bq to take Control of the FET's.

Do you think it would be OK to do the command 21 before the function tests and when finishing this testing - but before the PCB is attached to the cells,  change update status to 02 ?

Best regards

Kjell

Hi Kjell,

I would not recommend using 21, because once IT has been enabled,  it stays that way and the only way to disable it will be to load a .senc file on the device. Changing update status to 02 using EVSW does not enable or disable IT.

I do not really see how controlling the fet using command 46 is harder than using 21. Besides having to enter 46 word 0000 to turn off and 46 word 0006 to turn on and then running each tests I do not see how that adds to the delay.

thanks

Onyx

Hi Onyx,

Again, thanks for your support.

Your info is valuable, - I did not know that it is not possible to enable or disable IT from the DF Update status.

The reason for my question is actually - the function tester is a hardware based system with no SMB communication. To do the command 46 the PCB has to be removed from that fixture, connected to the programmer to load the 46 command and then back to the function tester again. This has to be repeated several times.

My last question - do you think that the errors that might be introduced by initializing IT during function testing - would they be corrected after a couple of charge - discharge cycles ? (may be a hopless question).

Best regards

Kjell

HI Kjell,

Now I see what you mean.

If IT is enabled before your tests, then running a few charge- rest- discharge- rest cycles should correct whatever errors was introduced.

Also, I believe whatever errors introduced by enabling IT before your tests can be avoided if you enable it when the cells are well rested, say about 2 hours  after a charge or about 5 hours after a discharge action. Also avoid enabling IT when your cells are in the disqualifying voltage range for your chem id. This range can be found in the excel sheet for the chem updater downloadable from our website. Then that way the possibilty of any errors being introduced by enabling IT instead of command 46 will be possibly eliminated.

thanks

Onyx