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BQ20Z95: Wont charge correctly with new cells

shawn DeBruyn
Prodigy 20 points

Part Number: BQ20Z95

Hello, I several packs that we are recelling. After new identical cells are installed the pack still charges the same like it did with the old cells. I get about an hour of charge time and an hour or so of use. When these packs were new they would charge for about 4-5 hrs and last 5-8hrs depending on use.

What do I need to do to retrain the BQ20Z95? 

Thanks

Shawn

  • 0
    TI__Expert 6575 points
    Hi Shawn,
    It is likely that you may have to download the golden gg file to the device so that it can re-train, since the resistance table and Qmax may be quite far off for the new cells.
    Also, if you can get an SBS Register Log file from bqEVSW while charging and discharging, I can check to see what exactly is happening during the charge and discharge. I will also need the ChemID you are using and the gg file from your pack.
    Regards,
    Swami
  • 0 in reply to Swaminathan Ramanathan75031
    Prodigy 20 points

    Hi Swmi, thank you for the reply.  Ok so it looks like im going to have to get into the ic. If I'm reading the ic layout correctly I need to solder a small wire to the SMBD and SMBC pin, and then wire that to the header on the ev2300. It mentions using a 10k pull  resistor. Is this what I will need to do? My IC is soldered to the factory controller board for the packs. So my next question is when I'm doing the reading and writing to the ic I assume we do this with the cells connected to the control board and that will power the ic? Or do i need to disconnect from the batteries and use an external 5v  power source from the ev2300? Sorry the literature I found is vague. Alot of good information for evaluation boards, but not so much for an ic that already implemented to a current in use pack. Unless I'm just not finding it.

    Thank you

    Shawn

  • 0 in reply to shawn DeBruyn
    TI__Expert 6575 points
    Hi Shawn,
    The cells should power the device, you don't need any external supply. In case the device goes to shutdown, you can apply a voltage to the PACK+ and this should make the device exit shutdown (Typically I short the Cell Stack BAT voltage to the PACK+ briefly to exit shutdown).
    The EV2300 should have pull-ups for the SMBus lines already. Apart from the SMBC and SMBD lines, please connect the Vss pin of the EV2300 SMBus connector to PACK- or ground on your battery pack.
    Here is the link to the Technical reference manual for bq20z95, this will give you more information on all the settings: www.ti.com/.../sluu264a.pdf
    Regards,
    Swami