- Added Tamura L06P400S05 hall sensor to example parts

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Michael Balzer 2017-07-29 11:17:52 +02:00
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@ -124,7 +124,7 @@ The bluetooth module is optional but neat, it enables to check your VirtualBMS o
Cell voltages can be measured using the multiplexer shown and simple voltage dividers measuring the stacked voltages, but keep in mind you lose precision by the scaling. The Arduino analog ports provide 10 bit resolution on the voltage range of 0-5 V = ~5 mV. So when scaling to 60 V, resolution drops to ~60 mV. This is good enough to detect a bad cell, but not for precise health monitoring. You may use ADC shields with higher resolution and/or differential voltage probes to get the single cell voltages, but when thinking about this, take a look at specialized battery monitoring chips like the MAX11080 or LTC6811 first. Cell voltages can be measured using the multiplexer shown and simple voltage dividers measuring the stacked voltages, but keep in mind you lose precision by the scaling. The Arduino analog ports provide 10 bit resolution on the voltage range of 0-5 V = ~5 mV. So when scaling to 60 V, resolution drops to ~60 mV. This is good enough to detect a bad cell, but not for precise health monitoring. You may use ADC shields with higher resolution and/or differential voltage probes to get the single cell voltages, but when thinking about this, take a look at specialized battery monitoring chips like the MAX11080 or LTC6811 first.
The pack current can be measured using either a shunt (with an [instrumentation amplifier](http://www.vwlowen.co.uk/arduino/current/current.htm) or an [ADC with preamp](http://arduinotronics.blogspot.de/2015/05/reading-current-shunt-with-arduino.html)) or a hall sensor module like the [LEM HAC 600-S](http://www.lem.com/hq/de/component/option,com_catalog/task,displaymodel/id,64.05.52.000.0/). The LEM outputs -4…+4 V so needs to be mapped to the Arduino's 0…5 V (i.e. using a voltage divider). The pack current can be measured using either a shunt (with an [instrumentation amplifier](http://www.vwlowen.co.uk/arduino/current/current.htm) or an [ADC with preamp](http://arduinotronics.blogspot.de/2015/05/reading-current-shunt-with-arduino.html)) or a hall sensor module like the [LEM HAC 600-S](http://www.lem.com/hq/de/component/option,com_catalog/task,displaymodel/id,64.05.52.000.0/) or the [Tamura L06P400S05](http://www.tamuracorp.com/clientuploads/pdfs/engineeringdocs/L06PXXXS05.pdf). The LEM outputs -4…+4 V so needs to be mapped to the Arduino's 0…5 V (i.e. using an offset voltage divider), the Tamura outputs 0…5 V (2.5 V = 0 A) so can be used directly.
The temperatures can be measured using LM35 sensors. Depending on the variant used, voltage may need to be mapped to the Arduino input. If you want to measure every single cell temperature, you can also extend the setup by another MUX for the temperature sensors -- just use the same address pins as for the voltage MUX. The temperatures can be measured using LM35 sensors. Depending on the variant used, voltage may need to be mapped to the Arduino input. If you want to measure every single cell temperature, you can also extend the setup by another MUX for the temperature sensors -- just use the same address pins as for the voltage MUX.