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Multi-Phase Electric Vehicle Charging Timer Disclosure Number: IPCOM000221014D
Publication Date: 2012-Aug-21
Document File: 2 page(s) / 32K

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Disclosed is a Multi-Phase Electric Vehicle Charging Timer that helps assure your electric car is charged when you need it.

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Electric vehicles, either pure battery electric vehicles (such as the Nissan* Leaf or Tesla Model

S) or range extended plug-in hybrid electric vehicles (such as the Chevrolet Volt** or the Prius*** Plug-in) use lithium battery chemistries for the traction battery. Such vehicles often have charging timers to schedule charging late at night to enable the user to take advantage of time-of-use (TOU) metering wherein electricity is purchased at lower "off-peak" prices, thereby improving grid utilization.

    One drawback to this simple charging timer mechanism is that the vehicle may return home with a low state of charge and be connected to the electric vehicle supply equipment (EVSE), but since it is not scheduled to begin charging until late at night, it will not be ready for an evening outing that may arise unless the user manually overrides the charging timer. Users may forget to do this, creating reluctance to use the charging timer function.

    Another drawback stems from the fact that lithium batteries generally experience their greatest longevity by minimizing time spent at either high or low state of charge (SOC). Simple charging timers leave the user with two options:

Charge immediately upon connection to the EVSE. This increases the likelihood the vehicle


will be charged if they need to use it, but results in unnecessary consumption of electricity at peak rates and increases the time the battery sits at a high SOC, since the charging will likely complete well in advance of being driven the following morning. This is most pronounced when the vehicle is not driven again during the evening.

Defer all charging until late night. This increases the time the battery sits at a low SOC in


cases where the vehicle returns home with a low SOC.

    This invention solves these problems with a charging timer that allows multiple phases to be defined. In the most likely application, the charging timer would charge the vehicle battery in two phases:

Phase 1: When the vehicle is connected to the EVSE at its home location, the SOC is evaluated. If the SOC is below either a threshold set by the manufacturer for low SOC for battery longevity or below a user-settable threshold for minimum SOC to be attained before deferring to TOU charging, charging begins immediately. Once the SOC meets these two thresholds, phase 1 charging stops.

Phase 2: Charging then resumes in the second phase, generally at the low TOU rate, to
complete vehicle charging to the desired SOC level.

This invention provide...