Fixing 0 mA Current Readings
on the BQ28Z610 Device
Custom driver for the BQ28Z610 device was connected directly via I2C. It is possible to obtain non-zero values from functions Voltage(), Temperature() and other. Charging and Discharging are allowed, current flow can be seen on the ammeter, but functions "0x0C/0D Current()" and "0x14/15 AverageCurrent()" always return [0x00, 0x00].
You may try increase actual current up to 1 A.
You may try to call function "12.2.15 AltManufacturerAccess() 0x0021 Gauging" to turn on the gauging of the current.
If nothing else helps, you should check your hardware circuit and test the sense resistor (Rsense). To do this, pass some current through it and measure the voltage across it in millivolt fractions.
For example, Rsence = 2m0 (2 milliohms). So current 1 A will produce 2 mV on it: "1 A * 2 mO = 2 mV".
To exclude the software component of the test, you need to:
- Disconnect load and charger.
- Take constant current source, at least 1 A, bigger - better.
- Take some load. You may use adjustable load to control the current.
- Take millivoltmeter, which can show fractions of the millivolt, or just microvoltmeter.
- Connect "current source +" and + of the load.
- Connect "load -" to the "B-" terminal.
- Connect "current source -" to the "P-" terminal (charger/load negative connection).
- Read voltage on the sense resistor on the test pins: "TB-" and "TP-" - it should correspond to the current.
- Change current and read voltage again - it should be changed as well.
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Reverce polarity of the current source - voltage on the Rsence resistor
should become negative as well.
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Test circuit independent |
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Test schema independent |
If the voltage is 0, then check your main circuit and try to clean it a little bit and remove any stickers - perhaps during production, sense resistor connections were shorted.
If the voltage is correct then build another test circuit:
- Connect the battery to the BAT terminals.
- Temporarily short terminals BAT+ and PACK+ to activate the microchip.
- Connect the load to the PACK terminals.
- Read voltage on the sense resistor - it should correspond to the current.
- Change current and read voltage again - it should be changed as well.
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| Test circuit via BQ28Z610 |
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| Test schema via BQ28Z610 |
If the voltage is 0 this time then the problem is in the microchip, the possibly it's a software issue, maybe it shorts the sense resistor by some configuration - but it was not my case, so I cannot confirm or deny if such a case possible.
Was used microchip BQ28Z610 at the battery pack from "JBL Xtreme 2", with the Device Name from the Data Flash: "ID1019-A-M26-28z610".
Resources
- BQ28Z610 Technical Reference Manual (Texas Instruments): https://www.ti.com/lit/ug/sluua65e/sluua65e.pdf
