BQ28Z610 connections when cell balancing unused?

MR Flashlight

Other Parts Discussed in Thread: BQ28Z610, BQ34Z100-G1

I'm working on an application which will have two Li-Ion batteries in a holder, where the mechanical constraints on my system prevent me from adding protection circuits within the batteries and also prevent me from accessing the center tap between the cells.

The BQ28Z610 seems to meet my needs for battery protection and a gas gauge, but I'm not sure how to connect the cells given that I can't do cell balancing. Do I connect the series cells to VC1, short VC1 to VC2, and turn off battery balancing? Do I connect the series cells to only VC2 instead?

over 7 years ago

0 ThomasCosby over 7 years ago

TI__Guru 73830 points

You will need to connect to all three points in the 2S battery stack when using the bq28z610. You can consider the bq34z100-G1, since it only monitors the stack voltage.

0 MR Flashlight over 7 years ago in reply to ThomasCosby

Intellectual 420 points

I am extremely space-limited, and the bq34z100-G1 is probably too big for me to use. Are there any options that stay at 4x4 mm or smaller?

0 MR Flashlight over 7 years ago in reply to ThomasCosby

Intellectual 420 points

In addition, the cell protections are far more important to me in this application than the actual gas gauging. The bq34z100-G1 does not do protection.

Would it be possible to connect a 50% voltage divider from 1N to 1P to 2P? That way the bq28z610 would always read the batteries as balanced?

0 ThomasCosby over 7 years ago in reply to MR Flashlight

TI__Guru 73830 points

You should be able to use a resistor divider to emulate the cell connections, but that will defeat your desire to support protection features. You really need to monitor both cells with this device.

Power management

Power management forum

BQ28Z610 connections when cell balancing unused?