Help on using BQ27532 EVM (BQ27532-G1 with BQ24250)

January 27, 2015, 10:52 am

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Hello

I've acquired this EVM because I was interested on low footprint area and the possibility of using just a I2C interface to access both gauge and charger.

The problem is that somehow the I2C interface used between BQ27532 and BQ24250 seems not be working. On the board there are 2 jumpers, JP4 and JP5 connecting the I2C clock and data pins. These jumpers are connected, and as I understand, it's the only setup needed on hardware.

Operating the BQ27532 software, I see that the ChargerStatus register is always with ERR bit set (bits WAIT_CMD and WFAIL change accordingly). I tried to enable/disable the charger I2C interface several times (GG_CHRCRCTL_ENABLE / GG_CHRGRCTL_DISABLE), but nothing happens. I've already tried to communicate directly with BQ24250 charger using another I2C adaptor (unplugging JP4 and JP5 off course), and it works normally.

Is someone there having the same problem?

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Fuel Gauge and Protection for 6S/12S application

January 27, 2015, 11:54 am

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Hello,

I am looking for a battery pack fuel gauge and protection circuitry for an application with the following specifications:

Chemistry: NiMH
Cells: 6S (7.2V) and 12S (14.4V)
Power Rating: 7-12 Ah
Peak Current: 20+ Amps
Gauge Accuracy: Ideally 2% or better

Does TI have any products which can be used for this application?

CAD Files for BQ33100EVM-001

January 27, 2015, 12:21 pm

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Are there CAD files available for this EVM anywhere (BQ33100EVM-001)?

We use Altium so that would be preferable, but anything would be better than nothing : )

Thanks,

Jarrod

bq27530EVM etc

January 27, 2015, 11:54 pm

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After experimenting with the kit/reading the manual I got one more question:

In the bq27530-G1 TRM (SLUUA73) references are made to registers Chrgr_InCtrl_Reg0, Chrgr_POR_Config_Reg1 and so on (see pages 22 to 28 in the TRM). How do these register/messages relate to the Flags / Status Bits shown in the bqEVSW's DataRAM page? 

Example:
bqEVSW DataRAM shows Chrgr_Ctl_Stat_Reg0 --> is this the same as TRM, page 22, Chrgr_InCtrl_Reg0 ???
bqEVSW DataRAM shows Chrgr_Supply_Stat_Reg1 --> TRM, ?????

Thx
MH

Help for new state of health device for car's acid-lead batteries

January 28, 2015, 8:29 am

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Hi everybody.

I am searching for best chip to design a state of health meter for acide lead batteries in the car.

As you know, the battery in the car can't be detouched from the car's electric system, nor it should discharge a lot, since as soon as your engine is on the alternator recharges the battery.

Indeed, I want to design a device able to measure the state of health of the car battery and predict its fault in some way.

The device has to stay connected to the battery ad the rest of the electric system , nor I can disconnect the battery or espect it to discharge ( if I could discharge it a litlle with a shunt while the engine is turned off ).

I am new to this battery world, so any basic information and chip solution would be appreciated.

Regards

BQ34Z100-G1 Features and Compatibility with BQ34Z100

January 28, 2015, 1:35 pm

≫ Next: BQ27510-G3, SOC, SOH, state of health

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Tom,

I've successfully implemented the BQ34Z100 in a prototype with high discharge currents (you answered some questions for me about a year ago under my old account: http://e2e.ti.com/search?author=179082). I plan on updating my design with the G1 part as it becomes available, but I had a couple of questions as I think through this design change.

The G1 appears to be pin-compatible with the pre-G1 version. Is this new version also binary compatible (so I can use my existing golden SENC files), or will I need to generate a new golden image for the new chip?

Finally, what improvements does this new version offer? I can't pinpoint many differences in the datasheets save for idle and active power consumption.

Thanks,
Ethan Zonca

BQ27510-G3, SOC, SOH, state of health

January 28, 2015, 2:47 pm

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I understood that battery capacity can't be determined instantaneously for a newly-inserted pack without some discharge activities being done  in a system-side fuel gauge setup. What about SOH? is SOH monitored in real time under Impedance Track? Does SOH updating require charge/discharge activities? How is percentage of SOH achieved, what factors impact SOH percentage? The SOH (0x1c/0x1d) unit is %/num, what does num stand for, discharging cycles? 

In my system, battery cell is for backup only, after it's fully charged there is no many activities, any suggestion for accurately monitoring SOC, SOH for my situation? Will be load test or certain charge/discharge activity be good for reliable SOC and SOH?

Regards,

Yunfa

BQ2084-V143 Remaining Capacity and Fuel Level not working

January 29, 2015, 1:52 am

≫ Next: BQ40Z50 I2C Test Sequence Available?

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Hi,

I did a disign with a BQ2084-V143 and a BQ29312A and they working good up to now.

I don't know why but now I have a problem with them... :

The Voltage, Current, Temperature, ... all the datas readed are good but not the remaining capacity. 

The remaining Capacity (and so the fuel level)  are not updated when I charge or discharge my batteries.

I have put the factory dataflash into the BQ2084-V143 but it change nothing.

The batteries I use are 4 cells, 2600mAh. For the moment my Fuel level is 100%, I discharge my batteries with an 1A load, and the Fuel Level stay at 100%

I have the same problem if I reset the system (Fuellevel 0%) I charge my batteries but the fuel level stay at 0%

Can I solve it ?

Thx

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BQ40Z50 I2C Test Sequence Available?

January 29, 2015, 1:15 pm

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Customer is interested in testing thei I2C interface between their processor and the BA40Z50.

From customer: Regarding compatibility with I2C. We are trying to confirm compatibility with a processor's I2C port (and modified software if necessary).  We are looking for a command / response test sequence that they can try to communicate with the SMBus ports on the bq40z50 EVM (bypassing the EV2300).  Can TI provide us such a sequence, which would stress a standard I2C port?

 

Thanks,

John

BQ20Z95 Configuration - Alternative methods for setting and clearing TDA, FD

January 29, 2015, 6:00 pm

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Hello,

On page 63 of SLUA404, Configuration describes an alternative method for setting TDA, FD, purely using voltage measurements.  How do I disable this method - I don't need it?

Thank you,

Jeremy.

BQ20Z95 AFE.State_CTL

January 29, 2015, 9:36 pm

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Should I configure the AFE.State_CTL register (part of BQ29330 onboard the BQ20Z95) using bqEVSW, or does the gauge itself configure this register?

Thank you,

Jeremy.

bq40z50 startup

January 30, 2015, 6:21 am

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I am new to the bq40z50 and I see the bqStudio has no new project wizard like the bqEVSW. I normally use the wizard to get basic settings and then "tweak" them to the desired values.

Is there a method (such as a template gg file) to get started for a 4S LiFePO4 project, or must I edit all of the parameters manually one by one?

Thanks,

Larry

BQ40z50 Balance Time

January 30, 2015, 7:06 am

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I'm currently trawling through the settings to configure my BQ40z50 for use with my cells. I'm intend to use the internal cell balancing and have got to the "Bal Time /mAh Cell 1" value. I'm not convinced my value is correct. For a cell with nominal voltage of 3.65V, I get 16274 which seems much larger than the default value of 367. Is the formula correct (is my calculation correct)? 

Vcell = 3.65; RVCx = 100; DUTY = 66; Rcb = 150

I suspect the formula isn't quite right as the V/R portion gives a result in Amps which is the used to divide a value in mAs.

Additionally, the datasheet says Rcb is max 200 but the Tech Ref says to use 150.

Thanks

BQ34Z100 learning cycle issue and wrong passed charge value

January 30, 2015, 8:00 am

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Good morning,

I'm trying to perform a learning cycle on a 10S4P Li-ion battery pack with a total capacity of 11400mAh. I've followed exactly the procedure reported into the SLUA597 with also some further advices received some months ago (when I did the same on a different pack), but after the proper execution of the preliminary discharging phase and first charging phase, I've got a problem at the end of the first useful discharging phase:

• Qmax value hasn't been updated
• Update Status remains at 05 value (instead of 06)

I've analyzed all the configuration and I have some doubts about a couple of parameters, but I don't know if they can influence the wrong result I've obtained:

• Cell Terminate Voltage: has such a parameter to correspond to the protection circuit cut-off voltage, i.e. to the minimum allowable value for the cell voltage?
• Qmax Max Delta %: is any update into the Qmax value accepted only if it is less than this percentage of the design capacity?

Concerning the second question, I've noted the Qmax value registered at its first update (i.e. after the first charging phase) is completely different from any reasonable value: it is around 16000mAh instead of about 11400mAh (i.e. the nominal value). With this wrong value of Qmax estimation (why is that been accepted if it was completely different from the starting value, set equal to the design capacity?), maybe a further update of Qmax, after the discharging phase, has been rejected because too distant from it, but closer to the correct real value...

At this point, I've tried to understand the reason for a wrong Qmax estimation. In a document received from TI I've found the following formula: Qmax = PassedCharge / (SOC1 - SOC2), where SOC1 and SOC2 are calculated at full charge and full discharge conditions (and they should be always something like 100% and 0% respectively). Looking at Passed Charge, I've found it is completely wrong and correspond to 16000mAh at full charge and at full discharge. So this seems to be a wrong behavior. How does the passed charge is calculated?

The current value is measured by the BQ34Z100 with a small error (below 0.5%, but the calibration procedure does not compensate such an error). Anyway such an error cannot justify the 40% error on passed charge (16000 instead of 11400). Maybe an error on timing could be?

Please let me know if you have any idea for understanding this wrong behavior or any suggestion for reaching a successful learning cycle.

Thank you in advance and best regards

Matteo

BQ76940 SCL bidirectional or unidirectional?

February 1, 2015, 11:30 pm

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Hi All:

In our bq76940 circuit, we need to add a I2C isolation circuit.

The I2C bus have only one master (MCU) and a slave (bq76940), I2C specification (www.i2c-bus.org/clock-generation-stretching-arbitration) says that 

Clock Stretching

I2C devices can slow down communication by stretching SCL: During an SCL low phase, any I2C device on the bus may additionally hold down SCL to prevent it to rise high again, enabling them to slow down the SCL clock rate or to stop I2C communication for a while. This is also referred to as clock synchronization.

Note: The I2C specification does not specify any timeout conditions for clock stretching, i.e. any device can hold down SCL as long as it likes.

So my question is that bq76940 will hold down SCL?

In my one master (MCU)  and one slave (bq76940) circuit, the SCL isolation circuit is bidirectional or unidirectional?

It will determine ISO1540 or ISO1541 i use to.

BR.

Peter

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Balance Time values BQ40Z50 always zero

February 2, 2015, 7:39 am

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Hello,

I'm using the BQ40Z50 with a 4 cell configuration.

I want to use the intern balance option so the function is enabled in the register.

I tried al lot of settings but the four belance timers always says zero, so the BQ40Z50 will never balance the cells.

The cells are enough out of balance.

BQ40Z50EVM question

February 2, 2015, 5:26 pm

≫ Next: I have only BQ76PL536 IC not evaluation board module. so how i should proceed forward with connecting batteries and making a BMS

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Is the purpose of the BQ40Z50 to be included within the battery pack, and not part of my product? After playing around with the BQ40Z50EVM I am starting to think this is the case...?

I am designing a product that is powered by 2 18650 batteries in series. I would like to be able to charge these batteries from within the device, or if the user wishes, they can remove the 2 18650 batteries and charge using an external charger.

I could use something like the bq24004, but this doesn't support cell balancing, gas guage, etc.. Is cell balancing required when charging two 18650 batteries in series? I asked the question on eevblog (link below) and got mixed results...

Does TI offer a solution for this? I assume the BQ40Z50 would not work, as it seems to require a lot of calibration, and needs to learn by monitoring cell charge / discharge?

www.eevblog.com/.../msg592577

I have only BQ76PL536 IC not evaluation board module. so how i should proceed forward with connecting batteries and making a BMS

February 2, 2015, 11:35 pm

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I have only BQ76PL536  IC not evaluation board module. so how i should proceed forward with connecting batteries and making a BMS .I need information about the connections and circuits.

BQ78350 Charge Termination

February 3, 2015, 12:19 am

≫ Next: BQ40z50 Pack Pin

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I have developed a new board with the bq78350/76920 to 76940.

Now i try to set the parameters so, that the BMS switch the chargingcurrent of, when the battery is full.

I have set the Tapercurrent to 250mA, the Term Voltage to 75mV and the fast charging voltage is set to 4050mV.

At the end of charging the the device stops the charging (CHG-Fet switch of) for about 1500ms and starts charging again for about 250ms.

What can I change, that the charging stops for longer time, or the cellvoltage falls to 4050mV?

For the adjustments I use the BQ78350EVM with a battery 10S1P.

Many thanks and best regards

Karl

BQ40z50 Pack Pin

February 3, 2015, 1:36 am

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Hi,

Is the PACK connection to the BQ40z50 used for anything other than getting the device out of shutdown mode? I'm wondering if I can put a FET in-line with the pack connection to the BQ (between BQ & P+, not between P+ and the DSG/CHG FETs). If I can do this, I can use a processor to control when the pack wakes up, rather than have it automatically wake as soon as voltage appears on P+.

Obviously a FET would drop 0.7-1.5V so the pack voltage measurement would be inaccurate but that wouldn't be an issue for my application, provided I can be sure the PACK measurement is not used for anything other than wakeup.

Thanks