I'm using the bqEasy Software for callibrating my Li-Ion pack. Wen done with the full training I get the following error:
"Dataflash.GasGauging.State.UpdateStatus does NOT = 2. Impedance track learning cycle was not completed correctly. Verify procedure and repeat."
What does this mean. Does the battery have to be fully charged before I click "All Done"
Ive upgraded the firmware on the EVM like you mentioned, and fixed a small number of configuration details that I missed before, and even after 3 or 4 more attempts I still can not get to an Update Status of 1. One thing ive noticed is that the RUP_DIS bit is set from the beginning, and does not clear until the relaxation time after the initial discharge before the IT is enabled. Ive read that the learning cycle is disrupted once this bit is set, but I cannot find anything that explains why it sets. Even right after I click the reset button on step 5 of bqEASY it is still set from the start. Can you think of any reason why this would be happening, or have any other suggestions as to why I am not able to complete a learning cycle? Thanks for your continued support!
It's normal for the RUP_DIS bit to be set until you enable IT. Unless the IT algorithm is running, updates to the resistance tables will not occur, and this is what RUP_DIS (R updates disabled) indicates.
Can you confirm that RUP_DIS is cleared (green) after you enable IT, but the VOK and QEN bits are set (red). This should be the condition after you enable IT, and before you start your charging.
I'm experiencing the very same problems here with BQ27510-G1. And after just a few weeks, we seem to be lucky compared to others trying "3-4 months" already ;-)
Cycle update doesn't change either. Not even to a 1. And it doesn't even give the measured capacity.
It would be very helpfull, if the device (or software) could give a hint, of why
it didn't want to accept a valid cycle. Just stating "didn't work" (my translation of the bit not changing to a 1) leaves me to making wild guesses about possible reasons. And try again and again. Maybe a future improvement of the firmware / BQeasy-software could detail on the reasons. It then would more deserve the name "BQeasy
As David has been emphasizing, the charge and discharge currents should be around C/2 and C/5. This would require my charger to charge with 3000mA. Our charger simply doesn't allow such high currents (max power dissipation!). Is this really an issue? Is a 1000mA charge ok? Recommended charging curves for Li-Ion batteries go from a constant current to a constant voltage charge. So, reducing the charging current is an inherent feature of the charger. Could this be the reason for the BQ not to accept the cycle as valid? (I would assume, the battery monitor would rather monitor, "as is" instead of insisting of "having an attitude").
Changing parameters in the BQeasy configuration often produces a runtime error when writing to the BQ. What is "runtime error 6, overflow
" indicating? I would like to make the configuration, that I think suits best my setup. But how can I, if the software doesn't tell me, where the problems with my parameters is?
As temperature seems to be an issue, can the max. allowed temperature limit be changed, after the battery has been fully charged, or do I need to discharge / charge all the way again? (Charging time, waiting time, discharging time, waiting time: 2 working days...).
Is there a way to speed things up somehow? I have seen, the BQ is counting relaxation time, charging time etc. Can the BQ be fooled, to go with a reduced waiting time? Or does it insist on the very last second? I can go with a reduced accuracy of capacity prediction, but I need a sucess now! Is there a way to force the cycle count to 1, if I know the battery is actually full?
Our charger is reducing charge (tickle charge) to a few 100 µA. Is this low enough for the BQ to detect a full battery?
It seems like the voltage measurements are sensitive enough to detect changes of 4µV. When discharging in a real-life device, some digital noise on the power paths is a common issue. Could that noise be a reason for the problem?
Termination voltage from the charger is nominally 4100mV. Accuracy is +/-50mV approx. Should I reduce this value in the configuration to make sure, this voltage is achieved in every circumstance?
Thanks for your help!
I've tried to address each of your questions:
--Usually when the Update_Status doesn't even get set to '1', this means that the gauge didn't learn a new capacity for the battery, which is the first step. In order to get a new capacity, you have to make sure that you are charging from a completely discharged condition all the way up to the full-charge condition. First, make sure that you discharge your cell all the way to the termination voltage. Then, charge your battery up to the point that it is full. This is where the problem usually lies. For Li-Ion, we use a CC/CV profile. You need to make sure that the charger continues to charge for a period of time AFTER it meets the taper current condition (set in step 2 of bqEASY). This way, the FC bit will be set, and the gauge can learn a new QMax. If the FC bit is not set after your charge, you will not learn.
Note that your charger voltage is 4.1V. make sure that this is reflected in your bqEASY settings. One of the termination conditions is that the battery have a voltage within 100mV of the charger voltage. If your bqEASY settings have it left at 4.2V, then this will never happen.
--With respect to charge/discharge rates: the C/2, C/5 guideline is really a maximum allowable charge/discharge rate. If you charge at less than C/2 or discharge at less than C/5, this is really not a problem. (In fact, it is arguably slightly better, but it takes a much longer time).
--I have actually never seen the 'runtime error 6: overflow'. Could you send me some details on how/when this happens? It might also help if you could post/send me your bqEASY project file or configuration settings. You might be writing something that is out of range.
--I'm a little confused by your question on temperature. You have a flash setting that you program a max/min charge and discharge temperature. This is generally set during step 2 of bqEASY and then left alone.
--Unfortunately, the process really cannot be sped up very much. The low (C/5, C/2) currents are needed so that the gauge can get an accurate picture of the battery's behavior. The relaxation period time is also necessary because the gauge must wait for the battery voltage to stabilize.
--Your charger should be OK in terms of current, just make sure that your charging voltage is set to 4100mV in bqEASY, and the taper current is set to a reasonably high current (~50-100mA is typical depending on application). Note that you cannot set the taper current below 1mA. Trickle charging to 100uA is OK, but make sure that the taper current is set well above this value.
--The voltage measurement is heavily filtered, and should not be sensitive to digital noise in our experience.
--Setting the charge voltage to 4100mV is OK. This means that the gauge will be looking for the taper current condition between 4 and 4.1 V to indicate termination of charge.
Let me know if this helps.
thanks for your answer.
-- This is what I tried to do. I discharged the battery down to 3400mV (below this voltage, my system will shut down anyway, so this is the lowest voltage the battery will see). I gave it some relaxing time and then started the cycle. If wouldn't want to post the logfile here, it's a bit lengthy ;-) If you give me your email-adr, I can send it.
I indeed reduced the termination voltage to 4100mV in the configuration. After it reached 4080mV, I forced the charger to shutdown, reducing charging current to 0. I then gave the BQ another 40 mins to "think it over". Taper voltage is 100mV, so it should have seen a full state.
-- You said, the charger needs to charge, even after the current dropped below the taper current. So, this means, I_charge>0 but < I_taper? How long does it need to see this? How large must this current be?
-- Here's my configuration:
-- As the temperature window seems a concern, I set the limits as wide as possible. I'm using the internal temperature sensor, as the external sensor is connected to the battery charger (I'm aware, that this will reduce accuracy later). Internal temperature of the BQ never went beyond 47°C.
-- Is there a way to work with an adjustable power supply in order to simulate a real life battery? While this wouldn't give any meaningfull impedance values, it could be a way to get a success in the cycle procedure. I start losing faith, I'll ever see cycle count turn to 2 before xmas...
-- And again: Why doesn't the software SAY, what is wrong? If I tell BQeasy, the battery is full, it IS full. If the BQ believes, some condition is not yet met, I expect it to just tell me.Like "temperature too high", "cell voltage hasn't reached maximum value", "taper current too high", "cell voltage hasn't stabilized". Is this really asked too much?
-- If TI believes, it's all so easy, would it offer a service to obtain
the golden configuration for us? We are willing to pay for it!
...another day over, another day hoping in vain. The flags VOK and QEN keep staying zero.
Unless you can point out a reason in my configuration, I'm giving up. I now understand, why competitors advertise their component with "no training cycle needed"...
Please email a configuration, that you think will work for my battery data. I'm willing to test everything, if there is a realistic chance, the counter will finally go upwards.
The screen shot you attached has show VOK and QEN bits are not set. Have you sent IT enable command?
I assume you already went through the app note: http://focus.ti.com/lit/an/slua544/slua544.pdf on how to generate golden image. No training cycle gauge is low end gauge and will not provide the high accuracy unless you want to go that route. If you can attach your gg file I will be happy to take a look. We have many customers who decided to use TI gauge for the best performance they are looking for.
I can see, those bits are not set. The key question is: why not? Of course, I have sent the IT command on the BQeasy.
Are you sure, I should include the logfile in this post? I've been logging the whole day and it is LONG. Maybe you can contact me by email, so I can send you the logfile that way.
Yes, I have read that app note. However, it still leaves my questions open.
I'm amongst the customers, who decided to use a TI gas gauge in order to get best perfomance - that's, why I have it on my PCB now. However, I'm not convinced, this was a good decision...
I actually is looking for DF dump (gg file) or DFI file so that I can see what has been programmed into the gauge. How do I contact you? May be a short phone call can clear things up.
here's my logfile from the last charging cycle.
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