Li-Ion BMS

Home resources about_technology about_charge_control

Charge Control

Letting the power company decide when you should charge (or discharge to the grid)

Charge Control: Smart Charge and V2G anchor

*Vehicle-To-Grid

Smart Charge and V2G are Charge Control technologies that let the power company control a plug-in vehicle's charging or discharging in real time:

  • to postpone a plug-in vehicle charging during time of peak demand, or
  • to buy back the energy from a plug-in vehicle's battery

It also enables both the owner and the power company to track the plug-in vehicle's usage and performance, while on the road and while charging.

What's the point of Charge Control? anchor
  • During times of peak demand, the power company prefers to reduce the demand, rather than turning on additional (dirtier and more expensive) power plants. In places that subscribe to such services, the power company shuts off appliances such as air conditioners until the peak demand is over. Similarly, Smart Charge allows the power company to postpone charging until the peak demand is over. Smart Charge is not as far reaching as V2G (a technology that allows the power company to buy energy back from a plug-in car) but is very effective because it is less expensive than V2G
  • The hardware used in Charge Control (V2G or Smart Charge) also monitors the vehicle (when driving or when plugged-in). As a side benefit, that information is available, through the web, to both the power company and the owner, for the purpose of tracking and optimizing the performance of the vehicle.
  • At this point there is no financial benefit from using Charge Control. However, one day the power utility may sell electricity at a lower price to charge Smart Charge vehicles, and may buy back that electricity back at a premium.
What's the difference between Smart Charge and V2G? anchor

In both V2G and Smart Charge, the power utility can control the power flow between a plug-in car and the power grid. However, in Smart Charge power only flows from the grid to the car, while in V2G power can flow in both directions.

Smart Charge block diagram V2G block diagram
Charge Control system diagram

In Charge Control (Smart Charge or V2G), a fleet of plug-in vehicles is fitted with Charge Control hardware, plus, optionally V2G.

Charge Control car diagram
Vehicle diagram

The Charge Control hardware is connected to the the servers of a company that manages Charge COntrol through the Cell Phone network and the Internet. The owners, the utilities and research organizations have access to data from each plug-in vehicle. In addition, the utility can disable charging, or request discharging (V2G).

Charge Control system diagram
System diagram
Sample screen of status report
Example of a status report for a plug-in vehicle with Charge Control, available in real time through the Web.

© 2008~2014 Davide Andrea. All rights reserved, except where noted by CC mark. Page published on Mar 23 2010. Graphic design by morninglori