BQ34Z100-G1: State of charge 0%

Hi Lukasz,

Can you please clarify if you experienced 100% capacity at startup and then it switched to 0%?

Can you please send me a log of the registers at startup and after it changes to 0%?

thanks

Miguel

Hello, thank you for answer.
I confim- the soc was 100% at the beginning and then switched to 0%.
I dont know how I can get you the csv from before changes, as everything is saved to non volatile memory. Is there any restore defaults command in bq studio?

Hello,
I have now observed another behavior: I discharged the battery to around 3.3 V (even though BQ studio said its 0% already). Then I started to charge it and left it for the night. I have seen that SOC % is rising. After Im back to work next day, the voltage is 4.4V (fully charged) and SoC is 0 % again... I dont have this logged on the graph, but I will now. What could be the case here?

Also I started logging this discharge run.

Hi Lukasz,

I will need to see the log. You can go see the picture below and it will create a log file automatically.

Thanks

Miguel

Thanks for answer Miguel,

At the moment I am logging the discharge process from a fully charged battery (in practice). In the software it shows 0% but its fully charged. After I do that, I will close logging, send you the files and start logging the charging process.

Hello Miguel,

In the attachement I add discharge and charhe log. The SOC is 0 % all the time, I dont understand this... I kindly ask you to shed some light on it please.bq.rar

Hi Lukasz,

I have a few more questions, but some initial findings show a bit of things that I need you to perhaps look into.

It seems that in your gg file under the Pack Configuration you have set 41d9 which according to the DS

So with this you have VOLTSEL to 0 which means that the internal resistor divider is chosen, but this is only for single cell packs. You will need to set this to 1 and use an external voltage divider.

Also your CAL_EN is enabled, i believe this should be set to 0 by default.

Are you using an EVM board for this?

Thanks

Miguel

Thanks for answer Miguel,

1. Yes I do have VOLTSEL to 0, since I have no external voltage divider. I am using 2 serial connected cells 2V each. This part was confusing for me- should I trick the BQ to think that I am using a single 4V cell? How should this be configured? This is my schematics:

Do you suspect what could be the case?

2. Yes, I do have CALEN set, as I forgot to turn it off. Can it affect anything?

Also, did I choose the chem ID correctly? I have simply taken the Enersys cyclon battery with 2500 mAh capacity. Mine is 5000 mAh and I have set that. Is this approach correct?

Hello,
Do you know what could be the case? The SoC keeps jumping between 0 and 100% for me... I am clueless now.

Hi,



Can you please add an external divider, since the BAT pin has to be around 1.5V or below. So this is probably why it is not just putting 0% capacity since it configured to work under single cell at the moment. Also please turn off CALEN.



Thanks



M

Hello Miguel,

But the total voltage is not 1.5 V, it is not possible in this config. The total voltage will vary from 4.4V to around 3.3 V at full discharge, please take a look:

That is why I use no physical external divider. I tried with series cells of 1 and 2, they both do not work. Should I also select external voltage divider even thought there is none? Bq shows 0% charge even thought the battery voltage is 4.3 V or similar, its visible in the logs.

The CALEN is off now, but that did not help, thanks.

Do you have any other ideas? This topic is starting to be really critical, as I was supposed to get this running long time a go but it still doesnt work. I would really appreciate your help.