BQ34Z100-G1: Design Energy Capacity

Fahad Akhtar

Part Number: BQ34Z100-G1

I have 16cells with 280Ah each, as such my design energy is 14336Wh. Design Energy parameter of the guage has upper limit of 32767. Hence even with x10 scaling, I cant enter actual design energy capacity of my pack

Please confirm this parameter is not important for guage performance. One way I am thinking to get around the upper limit is to assign a value of 1433 (3.2*16*280/10 @ x10 scaling) to this parameter and treat all the energy values coming from the guage as Wh instead of mWh

Best regards

Fahad

over 3 years ago

0 Jackson DiGiovanna over 3 years ago

TI__Expert 8315 points

Hi Fahad,

While it is technically possible use the method you described, the magnitude of your pack will make gauging much less accurate. While the energy scaling does not affect gauging if load mode is current based, You will still need to scale current related parameters by 155 (280*16/29 rounded up) because the design capacity of your pack is so large. We do not have concrete data on how a pack of this size would be impacted on scaling to this level so I would recommend testing on your design to see if the gauging accuracy is suitable for your application.

For more info on this you can refer to the following document https://www.ti.com/lit/an/slua760/slua760.pdf?ts=1657555074963&ref_url=https%253A%252F%252Fe2e.ti.com%252F.

Best Regards,

Jackson

0 Fahad Akhtar over 3 years ago

Prodigy 210 points

Jackson

Why are you multplying Ah by 16 to calculate scaling factor? All 16 cells are in series so Ah of the battery pack is 280Ah (i.e 280A for 1hr), which means scaling factor rounded up is equal to 10 (280/29)?

0 Jackson DiGiovanna over 3 years ago in reply to Fahad Akhtar

TI__Expert 8315 points

Hi Fahad,

Sorry, I forgot that these were all in series here. you would be correct. The scaling factor would be 280/29 rounded up which = 10.

Sorry for the confusion. With a scaling factor of 10 you should not encounter the large gauging inaccuracies I described previously.

Thanks,

Jackson

0 Fahad Akhtar over 3 years ago in reply to Jackson DiGiovanna

Prodigy 210 points

Jackson

My original question though still remains. Does Design Energy paramter value impact guaging performance (SoC and Qmax measurement specifically) in anyway because my pack energy is significantly higher than max value allowed for this parameter, even with x10 scaling.

Thanks

Fahad

0 Jackson DiGiovanna over 3 years ago in reply to Fahad Akhtar

TI__Expert 8315 points

Fahad,

As long as Load Mode is set to Constant Current rather than Constant Power (I believe Constant Current is default on this device) then all of the gauging parameters (like QMax and SOC) will be based off of Design Capacity not Design Energy. Because of this, Design Energy should not impact gauging performance.

Thanks,

Jackson

0 Fahad Akhtar over 3 years ago in reply to Jackson DiGiovanna

Prodigy 210 points

Thanks alot

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BQ34Z100-G1: Design Energy Capacity