TickTock
Well-known member
My recent observation that my car came back with more gids on an 80% and 100% charge while still drawing the same power from the wall led me to go back and check more logs on the value of 1 gid. Using three turtle to 100% logs (so non linearity won't be considered a factor), I computed the total energy into the battery as the integral of V*I*delta_t and compared to the power from the wall for the same charge. Then I divided both by the number of gids that charge added:
11/21/2011:
input:
gid start: 6
gid stop: 256
wall start(kWh): 508.93
wall stop(kWh): 531.57
battery start(kWh): 0
battery stop(kWh): 20.02
computed:
charger efficiency: 88.4%
wh/gid into battery: 80.0
wh/gid from wall: 90.6
7/6/2012:
input:
gid start: 6
gid stop: 217
wall start(kWh): 2857.34
wall stop(kWh): 2878.11
battery start(kWh): 0
battery stop(kWh): 18.50
computed:
charger efficiency: 89.1%
wh/gid into battery: 87.7
wh/gid from wall: 98.4
8/11/2012:
input:
gid start: 5
gid stop: 232
wall start(kWh): 2979.18
wall stop(kWh): 3000.01
battery start(kWh): 0
battery stop(kWh): 18.82
computed:
charger efficiency: 90.4%
wh/gid into battery: 82.3
wh/gid from wall: 91.8
I think since the efficiency (power_into_battery/power_from_wall) is pretty consistent, the power_into_battery computation should be valid --> although 80Wh may be the nominal target for 1 gid, it can be off by as much as 10%. Just something to keep in mind if you are counting gids and cutting your range close. Maybe my car just got out of cal and they recalibrated it for me when it was [Edit]at the Nissan Maricopa testing facility[/Edit] (between the 7/7 and 8/11 measurements), but I am going to be more cautious using a gid as an accurate unit moving forward.
11/21/2011:
input:
gid start: 6
gid stop: 256
wall start(kWh): 508.93
wall stop(kWh): 531.57
battery start(kWh): 0
battery stop(kWh): 20.02
computed:
charger efficiency: 88.4%
wh/gid into battery: 80.0
wh/gid from wall: 90.6
7/6/2012:
input:
gid start: 6
gid stop: 217
wall start(kWh): 2857.34
wall stop(kWh): 2878.11
battery start(kWh): 0
battery stop(kWh): 18.50
computed:
charger efficiency: 89.1%
wh/gid into battery: 87.7
wh/gid from wall: 98.4
8/11/2012:
input:
gid start: 5
gid stop: 232
wall start(kWh): 2979.18
wall stop(kWh): 3000.01
battery start(kWh): 0
battery stop(kWh): 18.82
computed:
charger efficiency: 90.4%
wh/gid into battery: 82.3
wh/gid from wall: 91.8
I think since the efficiency (power_into_battery/power_from_wall) is pretty consistent, the power_into_battery computation should be valid --> although 80Wh may be the nominal target for 1 gid, it can be off by as much as 10%. Just something to keep in mind if you are counting gids and cutting your range close. Maybe my car just got out of cal and they recalibrated it for me when it was [Edit]at the Nissan Maricopa testing facility[/Edit] (between the 7/7 and 8/11 measurements), but I am going to be more cautious using a gid as an accurate unit moving forward.