Original question:
Hi,
I am testing the eval board with 6 capacitors of size 1 F. When the voltage on one of the cells is 4 V, I activate balancing just for that cell. The voltage on that capacitor drops to 2.8 whereas I have set the VCBDONE to 3 V. Do I need to activate OVUV protection separately to use this feature of the GUI? I can see that tUV_CYCLE is 8 ms so I assume worst case scenario, the voltage on the cap should be checked at 16 ms and balancing should be stopped if the voltage is lower than 3 V.
Hi Taylor,
Our cells have limited current capability so I just want to make sure we do not pull high current from them in balancing process.
According to this picture and the eval board's schematics, balancing resistance will be 20 Ohm for one cell and with a 1 F capacitor, the time it takes for the capacitor's voltage to go from 4 V to 2.8 V is almost 9 seconds.
I measured the current from the capacitor that balancing is activated for and you can see that there are not high transients involved and the voltage goes down gradually. CB Run is green for a visible amount of time. So it seems like VCBDONE is not set to the value chosen on GUI or the IC takes way longer than tUV_CYCLE to check the voltage and finish balancing
My issue is that I set the UV limit here in the GUI and then I activate
but the voltages drop to 2.8 V.
It does not say in the manual to activate OV protection for this but I will check to see if it is activated by default.
There is not a section as 9.3.3.1.4 in SLUUC36 and SLUSDT5A. Which document are you referring to?
I have voltage protection here and tried both threshold locks:
OVUV_CTRL looks like this (set it at b01 manually)
VCB_DONE_THRESH was not set as UV value in the GUI. Changed that manually and still did not affect the balancing stop point.
Some of the AUX ADC values do not make sense. Can that relate to this?
I tried that. I set VCB_DONE_THRESH to 17, took steps 2 and 3 and then went to cell balancing tab and selected one of the cells to balance and it went to 2.8 V.
But I figured that if I set this value at 3.3 V, it will balance to 3.03 V so it seems like it is off.
VCB_DONE_THRESH is 31 when that variable is set to 4 whereas based on datasheet it should be 0x3F = threshold of 4-V. So it seems like the GUI does not set the threshold correctly and I cannot set it manually in the register because then I have to activate balancing manually as well and I still do not know how to do that (will read the datasheet for that).
