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BQ20Z655-R1: Using 2S2P user-replaceable LiPo battery

Eesu
Prodigy 205 points
Part Number: BQ20Z655-R1
Other Parts Discussed in Thread: BQ40Z50-R2, BQ34Z100-G1

Hi,

We want to use 2S LiPo battery pack and we want the battery to be user-replaceable. We are considering 2S2P pack. My questions are:

  1. Is BQ20Z655-R1 right IC for this application?

  2. Are there any issues with using 2P batteries? Because the gauge will be measuring two cells in parallel and consider them as single cell.

  3. Are there any issues with the fuel gauge when the user replaces the battery regularly? How will the gauge keep track of the batteries each time the batteries are replaced?

  4. Are there any other considerations to be made in this design or can I treat 2S2P as 2S1P?

Thank you.

  • 0
    TI__Guru* 76230 points
    hi Eesu,

    The bq20z655 will not be ideal for your application as it is a pack side gauge and it is old. If you are considering using a pack side gauge, the bq40z50-R2 is your best choice. Note that with pack side gauges, the cells are not supposed to be replaced. They are always supposed to be attached to the gauge so that it maintains high accuracy. It isn't recommended for multi-cell applications for the cells to be replaceable because the end user may place in unbalanced cells and that will cause one cell to age faster than the other. If there is a means of ensuring that the cells are at the same voltages upon battery insertion, then consider using our multicell pack-side gauge which can work as a system side gauge- the bq34z100-g1. It doesn't measure the individual voltages of the cells but rather the stack voltage. Again i have to emphasize you have to ensure the cells are balanced.

    thanks
    Onyx