BQ33100 EVM with 5 cells question

Seonghyun Kim

Hello,

I work with the bq33100 EVM. I connected 5 caps (120F, 9mOhm, 2.8V) to the board. The value of capacitance I expected was 24F, but the measurement from the board is 17.5F when I started a learn cycle with command 23. What could be the reason for this fault?

The ESR measurement is also different. I expected 5*9mOhm=45mOhm but the board gives 139mOhm.

I attached my log file and .gg file.

bq33100evm_0.zip

Please give some suggestions or comments for the issue. Thanks.

Best regards,

Kim

over 8 years ago

0 Benjamin Lough over 8 years ago

TI__Mastermind 27145 points

Hi Seonghyun,

Make sure that voltage and current have both been calibrated on the EVM. Try initiating the learning cycle when your voltage is close to Vnominal and not immediately after power on.

Page 15 of the datasheet provides more information on the calculation of capacitance and ESR:www.ti.com/.../bq33100.pdf. Capacitance measurement is based on I=C*dV/dt. ESR is calculated as ((V at rest)-(V at initial discharge))/(I discharge).

Best Regards,
Ben Lough

0 Seonghyun Kim over 8 years ago in reply to Benjamin Lough

Prodigy 25 points

Hi benjamin,

Thanks for your reply.

I tried to initiate learning cycle when voltage is close to Vnominal but nothing change.

Please help me one more time.

I attatched word file. It contains what I did.Help me.docx

Best regards,

Kim

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BQ33100 EVM with 5 cells question