BQ34110: How can I manipulate the "Remaining Capacity"?

Hi Shirish,
Thank you very much for your input. Eventaully I got little uncertain, if I have selected an approprate fuel gauge for my application. May I ask you to have a quick look to the following quesiton: Questioning the selection of the fuel gauge.

I have replied on the other thread

Meanwhile it seems like I have more or less successfully set up the fuel gauge. However, "Remaining Capacity" remains a little mystery.When start to charge empty batteris, it starts to increase "Remaining Capacity". However, it suddenly jumps up (gets sync) to Full Charge Capacity. The same thing happens when starting to discharge, it emidiately jumps down to a very low value (almost empty), and from there it decreases correctly by the amount of discharge.

Now, the first is probably because it determined fully charged batteries, causing it to sync RC with FCC (that's because CSYNC is set). However, I'm unable to understand the aprupt loss of charge when starting to discharge...?

You may have an answer to that?

Best regards
Nik

Hello Nik,

Have you used the GPCCEDV tool to set gauging parameters?

Hi Shirish,
No I haven't. I haven't because it required 6 log files, of which two pairs require different environment temperature then room temperature. As I don't have a climate chamber I remain unable to provides such log files. Thus, I'm unable to use this tool.

However, I am going to have different batteries inserted (i.e. NiMH with different capacities, as they are accessable for replacement by customer). Neither do I need to be super precics but may gain the ability to provide about 5 different state of charge (so no IPhone, no smart watch,...). Having Li-Io batteries I would simply take the voltage, however, NiMH have a very flag voltage descent, which makes it hard to determine the state of charge simply by voltage, even if only a few state are required.

Now, there's where I am. I mean, as all parameters are referenced to a single cell and the number of available chemistries (or covered by this fuel gauge) is very limited, there are of course default values (as the default values already programmed, unfortunatelly for Li-Io batteries, not for NiMH, what a pitty). So TI may provide such default values, as this would probably simply solve my issue, which otherway may take a few days/weeks until I successfully can use this deivce.

Best regards Nik

Hi Sirish,

Thank you for responding. 

I already have set the flag "FIXED_EDV0". 

I also have defined the fixed EDV 0 to 2 and all the DOD values:

However, as soon as I start to pull load from the battery the "remaining capacity" droppes from 2200 mAh down to 153 mAh, which doesn't make sence to me so far. However, I am unable to find any settings/description that the remaining capacity is recalculated as soon as I start to make us of the battey.

So you may help me out here?

Below I show the process when (on the left) just finished charging. The FG stated FC, thus reset "Remaining Charge" to 2200 mAh. However, as soon as I start the load of about 100 mA, the battery status immediatelly states "low charge" (??) and the remaining charge is set to about 153 mAh. The voltage is still on a level of about 1.37 V per cell. 

So what causes the remaining capacity to drop?

Best regards

Nik

Hello Nik,

I would check if charge termination parameters are set correctly in Operation Config A and "Charger Control"

Hi Shirish,

Here ar the settings in Operation Config A

and the Charge Control Settings

Do you see anything suspecious?

Hi Shirish,

Thank you for responding. Currently I have 4x 1.2V 2300mAh Energizer: link to datasheet: https://data.energizer.com/pdfs/nh15-2300.pdf.

So far, "Accumulated charge" is kind of useable, whereas "Remaining capacity" has a huge jump downwards, as soon as I start to discharge.

Kind regards

Nik

Hello Nik,

Just want to make sure that you completed a learning as described in TRM section 2.7.3 Capacity Learning (FCC Update) and Qualified Discharge

Hi Shirish,
I have noticed this section so fare. However, as I focused on the sections containing "Remaining Capacity" instead of also "RC" (that suddenly occurrs), I have to digg into this section. But this will take an other few days. Thank you very much so far!

Best regards
Nik