Argonne Labs Downloadable Data

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bwilson4web

Well-known member
Joined
Apr 30, 2016
Messages
805
Location
Huntsville, AL
Hi,

One of my favorite data sites is Argonne National Labs because the detailed, quality engineering data they make available. Here is the URL for their BMW i3-REx shared in September 2015:
http://www.anl.gov/energy-systems/group/downloadable-dynamometer-database/plug-hybrid-electric-vehicles/2014-bmw-i3-rex

They take a test car, instrument it, and put it on a dyno in an environmentally controlled lab:
i3_rex_060.jpg

The instrumented test vehicle provides independent metrics. So notice they listed the actual traction battery as '18.1 kWh' versus the BMW specs of '18.7 kWh'. Both can be right because they were measured at different times with different test articles. My car would no doubt have different values.

The biggest contribution are sharing the Argonne collected data:
i3_rex_061.jpg

The somewhat difficult to deal with PDF files list the name of the associated data files at 20F, 72F, and 95F, test file names, and summary of the test environment. The '*.zip' files contain the raw data, tab-delimited text files that can be loaded into a spreadsheet. For example, the test 'SSS 0-80-0 0% Grade' is associated with test file '61504034.txt'.

The 'SSS 0-80-0 0% Grade' tests, two of them, are steady state, 0 to 80 to 0 mph, on a 0% grade:
i3_rex_035.jpg

Within that file are these data fields:
  • Time[sec]
    Dyno_Speed[mph]
    Dyno_Tractive_Effort[N]
    Test_Cell_Temp[C]
    Test_Cell_RH[%] Phase_#
    HV_Battery_Voltage[V]
    HV_Battery_Current[A]
    HV_Battery_SOC[%]
    Range_Extender_Speed[rpm]
    Engine_Oil_Temp[C]
    Fuel_Flow_FuelScale[cc/s]
    Range_Extender_Current[A]
    Accelerator_Pedal_Position[%]

Now I have a special interest in the 'mi/kWh' as a function of mph. This is what Argonne data provided:
i3_rex_036.jpg

Now the data is captured at 10 times per second, very detailed, and sometimes there is evidence of 'drift.' So in this case, I collected the data into 10 mph buckets and averaged the traction battery power. So be careful when analyzing the data.

Still, I used this data to adjust my model for a better overhead metric, 540W. This is my current, best estimate of the static overhead load of the car for this chart:
i3_rex_030.jpg

As I'd reported before, the field data strongly suggested my BMW i3-REx has (had) a problem with wheel alignment which wore out the tires at 7,400 miles.

My particular i3-REx has been in the local BMW shop for a week getting a 4-wheel alignment that led to four, new tires as well as getting the previous service actions applied. In effect these service actions are bringing my recently purchased car to as close to new as possible. Once I get it back, I will repeat my earlier tests and share the effect.

I have only scratched the surface of the Argonne Labs data and how it can lead to a set of engineering charts defining the i3-REx performance. Remaining for future analysis includes hill climbs, 20F, and 95F data.

Bob Wilson

ps. There is a BEV only page too: http://www.anl.gov/energy-systems/group/downloadable-dynamometer-database/electric-vehicles/2014-bmw-i3-bev
 
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