BQ78350-R1: How to stop charge termination caused by incorrect RSOC/ASOC values?

Gary Bloomfield

Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQSTUDIO

On a new battery pack design and after a few charge and discharge cycles the pack stops charging with a 100% RSOC & ASOC – TC and TCA are set. However looking at the voltage, the pack is not 100% fully charged. If we discharge the pack some more then we are able to start charging again.

Our application does not need the RSOC or ASOC information – only the over voltage, temperature, short-circuit, etc. protection.

We changed the SOC Flag Config to 0x28A which disables the FCSETRSOC, TCSETVCT, FCSETVCT, and TCSETRSOC bits - thinking that TC would not get set. However, TC still gets set to 1 after a few charge/discharge cycles and charging gets disabled with TC set to 1.

Can all of these conditions (FCSETRSOC, TCSETVCT, FCSETVCT, and TCSETRSOC) be disabled at the same time? If so, why would TC still be set if these bits were disabled (0)?

Or, do you have to pick whether to use RSOC or VCT (primary charge)?

Thanks.

over 5 years ago

0 Dominik Hartl11 over 5 years ago

TI__Guru 61516 points

I would make sure that your charge termination configuration is correct. Please set the Charge Term Taper Current and the Charge Term Voltage so that it is compatible with your charger - then this will fix your problem.

Check chapter 5.3, http://www.ti.com/lit/ug/sluubd3d/sluubd3d.pdf

0 Gary Bloomfield over 5 years ago in reply to Dominik Hartl11

Prodigy 100 points

I have reviewed the section, but maybe I was focused on a tree instead of the forest before. To restate the issue, we have a 13Cell pack. When we run a "job" if the pack only discharges to about 3.0V per cell, the pack will not accept a charge [CHG=0, FCHG=1, FC=1, TC=1, VCT=1, ChgM=1, AM=1, ICC=1]. We have to manually discharge the pack until the cells are below 3.0V per cell before the pack will accept a charge. Once charging, it charges to a full charge (going by cell voltage) and terminates the charge properly.

0 Matt Sunna over 5 years ago in reply to Gary Bloomfield

TI__Guru* 81034 points

Hi Gary,

Can you capture a log file using BQStudio with this behavior (click Start Log in the Register screen)? This will help to debug exactly what is happening that is preventing the CHG FET from turning on. Also, can you please send your data flash settings (Export from the Data Memory screen)?

Thanks and best regards,

Matt

0 Matt Sunna over 5 years ago in reply to Matt Sunna

TI__Guru* 81034 points

Hi Gary,

Do you have any update on this issue?

Thanks,

Matt

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BQ78350-R1: How to stop charge termination caused by incorrect RSOC/ASOC values?