Calibrate battery with BQ34Z100PW

Roel Klarenberg

Hi,

I've a problem with the calibration of my battery with the BQ34Z100PW.

My battery specs:
26.4V
12 Ah
316.8Wh

The problem is my capacity in the data ram isn't the same as the design capacity I programmed to the BQ34Z100PW.
I thought when I use the learning cycle, the capacity will change.
But when I start the learn cycle the VOK bit is still high after 3 hours.
I followed this document http://www.ti.com/lit/an/slua334b/slua334b.pdf.
The charge current is 4A and I discharge with 2.4A.

Also I need to use the X10, because I need to fill in 316.8Wh.
What is the effect for the other settings of the X10.
Because when I read page 19 of the datasheet I can't find which settings are scaled.

I look forward for the answers on my questions.

over 11 years ago

0 ThomasCosby over 11 years ago

TI__Guru 73830 points

Roel,

It looks like you can just use the Design Energy Scale and you will not need to use the X10 mode as long as the Design Energy is the only parameter that is too large. You can set the Design Energy Scale to 10 and enter the parameters presented in Table 10 of the datasheet by divide-by-10. You will not need to adjust the current entered during calibration.

Regards

Tom

0 Roel Klarenberg over 11 years ago in reply to ThomasCosby

Prodigy 40 points

Tom,

I see the design energy scale is at the moment 10, but I set all values 1:1.
For one cell the calibration is succeeded (status is set at the end 0x06), but with the design energy scale at 10.
I doesn't set the X10 bit, because a single cell is 3.3V with a capacity of 1500 mAh.
Does the design scale has any effect for the calibration?
I think the design scale can easy solve my problem, as I understand from you.

Kind regards,

Roel

0 Roel Klarenberg over 11 years ago in reply to Roel Klarenberg

Prodigy 40 points

I use the constant current mode.

So load = 0 and Select = 1.

0 ThomasCosby over 11 years ago in reply to Roel Klarenberg

TI__Guru 73830 points

Roel,

The Design Energy Scale does not affect calibration.

Regards
Tom

0 Roel Klarenberg over 11 years ago in reply to ThomasCosby

Prodigy 40 points

Tom,

Thanks for the answer.
I've a question about the FC bit.
I read in the datasheet you can choose between state of charge or charging and charge termination indication.
Is for calibration the charging and charge termination indication not the best option?

Kind regards,
Roel Klarenberg

0 ThomasCosby over 11 years ago in reply to Roel Klarenberg

TI__Guru 73830 points

Roel,

You can choose between two conditions to set the FC bit during charging.

If FC Set%=-1, then the FC bit will set after the voltage and taper current requirements have been met.

If FC Set%= a percentage value, then the FC bit will set after the SOC reaches that percentage value.

I am not sure what you are referring to on the calibration comment.

Regards

Tom

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Calibrate battery with BQ34Z100PW