BQ34Z100-G1: replace a battery with less charge

Andres Suarez

Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQ34Z100

Hello,

I'm monitoring two batteries with the BQ34Z100-G1, I need to switch the batteries in specified moments.

I'm facing a refresh problem with the SOC after I switch one battery (the batteries are the same model), but only when the SOC of the battery that is replaced is higher than the new one.

For example: BAT1_old SOC = 90% switched with BAT1_new SOC = 60%.

The value of the SOC stays at 90%, even when the battery is discharging.

This a problem related to the algorithm used to calculate the SoC or is a problem of programming?

Best regards,

Andres Suarez

over 5 years ago

0 Steven Yao over 5 years ago

TI__Genius 12215 points

Hi, Andres

Does the bq34z100 experience a power cycle when you switching the battery.

bq34z100 is a pack side gauge, but if you do want to switch it from one battery to another, please make sure the battery is well relaxed when the bq34z100 module is switching to it

0 Andres Suarez over 5 years ago in reply to Steven Yao

Prodigy 150 points

Reading more about the bq34z100 I found that it can be used as a pack side as well as a system side. Described in the DS https://www.ti.com/lit/ds/symlink/bq34z100-g1.pdf, section 8.2.4.

The description of the bq34z100 doesn't specify that the battery should be relaxed, but I don't know why the SoC is not updated.

0 Kang Kang over 5 years ago in reply to Andres Suarez

TI__Mastermind 24870 points

Hello Andres,

Perhaps this document will help. It applies to most general IT gauges.

http://www.ti.com/lit/an/slua364/slua364.pdf

I would recommend to use pack side architecture when possible. That way the gauge is always attached to the cell instead of the system to avoid POR. We will need relaxed battery voltages to compute initial capacity correctly.

0 Andres Suarez over 5 years ago in reply to Kang Kang

Prodigy 150 points

Hello Kang,

I understand, this requirement is the only one to swap the battery. I'll consider changing to a pack-side gauge.

Thanks for all

Power management

Power management forum

BQ34Z100-G1: replace a battery with less charge