Friday 21 January 2011

Standby power consumption

Deutsche Version
To have an idea, what is the standby power consumption of the wallbox and the car, I watched the electric meter that was installed with the new power cable feeding the wallbox in the garage. 
Due to the electric meter switches digitally in 0,1kWh-steps and I do not have higher sophisticated measuring equipment, this is not more than an estimated conclusion.

Monitoring the electric meter for several days without pluging in the car shows a power consumption of 0,1kWh/24h. This may be slightly more because of  the digital switch.
So the Siemens wallbox has a standby power consumption of about 4,2 Watt (or slightly more).
This is not a big value, but projected to the period I use the MINI E (9 1/2 month, 285 days) this means 285x0,1kWh = 28,5kWh. This is equal to a full charge of MINI Es usable battery capacity of about 28kWh. At a price of 0,207 Euro/kWh this is about 5,90 Euro for the powering of the wallbox during the test period.
Integrating some smart grid features, the power consumption may rise and developers and customers should have an eye on this.
Whenever I do not need the wallbox for a longer time, I shut it off via the circuit breaker.

Monitoring the electric meter with the car plugged in after achieving a SOC of 100% and the flashing charging light is gone, the effect is the same: 0,1kWh/24h combined consumption of wallbox and fully charged car.
So it seems that the MINI E has a negligible power consumption when it is fully charged and there is no need to plug it off to avoid some extra cost.
 
Siemens Wallbox with plugged in MINI E.

This issue changes with the next generation electric vehicles providing thermal management of the battery pack and preconditioning of the cabin.

I hope the driver may choose from different scenarios ranging
... from full range priority providing optimum battery temperature and fully conditioned cabin neglecting the energy consumption
... to an eco mode with priority to minium energy consumption providing just in time battery temperature sufficient for using the regenerative brake and a moderate cabin temperature.

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