BQ27520-G4: Maximum Capacity

Nicholas Carley

Expert 8185 points

Part Number: BQ27520-G4
Other Parts Discussed in Thread: BQ27Z561-R2, BQ27220,

The datasheet contradicts itself on the maximum capacity.

Section 9.1 says the maximum capacity is 14.5Ah but Section 1 (and the website) says it supports 32Ah. Which one is it?

Nick

over 2 years ago

0 Jackson DiGiovanna over 2 years ago

TI__Expert 8245 points

Nicholas,

This is a typo in the datasheet that we will get fixed. The correct max capacity for this device is 14.5Ah.

Thanks,

Jackson

0 Nicholas Carley over 2 years ago in reply to Jackson DiGiovanna

TI__Expert 8185 points

The customer's capacity for their configuration combines to 14.8Ah. Will this mess up the algorithm in a meaningful way? Or just less accuracy of the SoC?

0 Jackson DiGiovanna over 2 years ago in reply to Nicholas Carley

TI__Expert 8245 points

Overflow can occur if 14.5Ah is exceeded which would cause tons of errors. I would not advise exceeding the 14.5Ah limit.

0 Nicholas Carley over 2 years ago in reply to Jackson DiGiovanna

TI__Expert 8185 points

Hello,

This is a consistent issue on multiple devices, including the BQ27546... What is a solution that actually supports >14.5Ah?

Nick

0 Wyatt Keller over 2 years ago in reply to Nicholas Carley

TI__Guru** 102355 points

Hello Nick,

The BQ27Z561-R2 is our flagship single cell gauge which should support up to a 30Ah battery.

Sincerely,

Wyatt Keller

0 Nicholas Carley over 2 years ago in reply to Wyatt Keller

TI__Expert 8185 points

Hi Wyatt,

Thank you for the recommendation, long term this will be a good solution. Are there any devices that for sure do >14.8Ah that have some immediate units available?

Nick

0 Wyatt Keller over 2 years ago in reply to Nicholas Carley

TI__Guru** 102355 points

Hello Nick,

The supply changes quickly and I'm not sure which device would have stock and where from.

Sincerely,

Wyatt Keller

0 Sindre Georgsen over 2 years ago in reply to Jackson DiGiovanna

Prodigy 20 points

Hi,

Originally we used BQ27220 in our product (still in development) but due to component situation we can no longer find stock for it so we have preliminiary changed to BQ27520-G4. Our battery pack is 4 cells in parallell to increase capacity to a total of 19400mAh.

I found this document in another thread that describes how to bypass the capacity limit by scaling certain registers /cfs-file/__key/communityserver-discussions-components-files/196/Gauge_5F00_Design_5F00_Configurations_5F00_for_5F00_High_5F00_Charge_5F005F00_Discharge_5F00_Rate_5F00_Applications_5B00_1_5D00_.pptx

Does this workaround applies to BQ27520-G4 also? If not can you redirect me to another fuel gauge (preferrably in stock) that can handle 19400 mAh since I can't trust your parametric search engine?

Is the battery capacity a limit for the Impedance Track algorithm only, or does it also applies to CEDV algorithm? I can't find anything in the BQ27220 datasheet regarding this limitation.

-Sindre

0 Wyatt Keller over 2 years ago in reply to Sindre Georgsen

TI__Guru** 102355 points

Hello Sindre,

You should be able to calibrate any of our gauges to a lower current value (for example apply 2A and calibrate the gauge with input as 1A.) Then you would need to decrease any of the capacity and current inputs for your battery by 1/2.

Sincerely,

Wyatt Keller

Power management

Power management forum

BQ27520-G4: Maximum Capacity