Power Management Overview
Power management is an essential feature that helps site hosts significantly reduce costs associated with their charger installations. This is achieved through the intelligent sharing of existing power among groups of chargers. By optimizing the use of available power, site hosts can avoid expensive infrastructure upgrades and ensure efficient energy distribution.
Your dashboard is equipped with several advanced features and capabilities designed to support complex commercial installations. These features aim to maximize the efficient utilization of power capacity, thereby saving site hosts on infrastructure costs. The key features include:
- Flexibility: The system is capable of modeling a wide variety of complex installations. For example, it can handle: Multiple circuits at a single location, allowing for diverse and adaptable power distribution setups and hierarchical model that supports tiers of nested sub-panels under main panels.
- 3-phase power: The system represents charger phase wiring to allow for power allocation by phase. This method ensures the most efficient use of available capacity, which translates to reduced costs for site hosts.Additionally, other power-consuming devices sharing circuits with chargers are represented in phase wiring, providing a comprehensive view of power distribution.
- Reallocation of power: When vehicles reach full charge and the charging process slows down, the system reallocates power to other chargers. This maximizes the efficient utilization of available capacity. This reallocation leads to faster charging speeds for drivers and further cost savings for site hosts.
- Round robin for over-subscription: In scenarios where a breaker is oversubscribed by chargers such that even their minimum charging power (e.g., 6A) would exceed the breaker's limit, power is allocated in a round robin fashion. This method ensures that power remains within safe operating limits. This feature is particularly useful for long-term parking use cases, such as those found at airports.
The diagram below shows an example of our EVEMS in action with four 32 A EV chargers installed on a circuit that only has 80 A of power available. Power is distributed based on the number of EVs plugged in and requesting a charge, but never exceeds 80 A.
Use Cases
The power management dashboard is meticulously crafted to support three essential functions, enhancing operations across different roles:
- Demonstrations by Sales Teams:
- Visual Interface: The dashboard features a graphical interface that enables sales teams to effectively present and demonstrate the capabilities of the power management system.
- Client Engagement: Through this visual tool, potential clients can visually comprehend the system's benefits and functionalities, facilitating a clearer understanding of its value.
- Installer Validation:
- Deployment Confirmation: Installers receive immediate visual confirmation of successful system setups. The dashboard displays power management rules applied to specific locations, verifying that installations are completed correctly.
- Confidence and Assurance: This instant feedback provides installers with the assurance that all components are functioning as intended, promoting confidence during and post-installation.
- Troubleshooting by Technicians:
- Real-Time Monitoring: Technicians can monitor power allocations for individual chargers and entire power management groups directly from the dashboard.
- Efficient Diagnostics: The ability to view this data in real time is vital for quickly diagnosing and addressing any operational issues, thereby minimizing downtime and enhancing system reliability.
FAQ
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- Presently, power management must be set up by the Power Management Team working in conjunction with the certified electrician that is installing your EV chargers. Power management is not enabled by default when deploying a new EV charging site.
There is no software limitation for the number of chargers that can be set up on the same circuit. We advise against severe over-subscription, since OCPP EV chargers have a minimum amperage they will output while still delivering a charge. The minimum amperage most Level 2 chargers will output is between 6–8 A, but this varies depending on manufacturer.
For a 100 A panel or circuit, we set a usable limit of 80% or 80 A within our system. If you are deploying chargers with an 8 A minimum output, we would recommend deploying a maximum of 10 chargers on the 100 A circuit. This is because 10 × 8 A = 80 A, or 80% of the circuit’s limit.
If you are deploying chargers with a 6 A minimum output, you could deploy up to 13 chargers on the 100 A circuit (13 × 6 A = 78 A).
Assuming the installation of 32 A EV chargers, only 2.5 chargers would fit on a 100 A circuit without power management. Using the examples above, power management enables an expansion ratio of 1:4 in the case of chargers with an 8 A minimum, and greater than 1:5 in the case of chargers with a 6 A minimum.
In general, you can calculate the oversubscription rate that a given charger will support using an equal charger algorithm by dividing the output power of the charger by the minimum amperage. A 32 A EV charger with a minimum output of 8 A would support oversubscription of 32 A ÷ 8 A = 4. So you could quadruple the number of chargers your infrastructure would support without power management. An 80 A EV charger with a minimum output of 8 A would support oversubscription of 80 A ÷ 8 A = 10. Or 10× the rated capacity.
If the chargers you are installing support 0 A Charging Profiles, you can expand a circuit even further by using round-robin charging.
This power management system is designed to re-allocate amperage any time there is an update to the status of a charging session. Here is what happens when a new car plugs into a charger that is part of a power management group:
- The vehicle requests a charge from the charger. The charger communicates this request with the CSMS.
- The CSMS re-calculates power allocation based on the selected algorithm.
- Before power is allocated to the new vehicle, the system will first reduce the power for ongoing sessions to ensure a safe transition.
- After the system has confirmed successful decrease of power across all ongoing sessions, the new session will begin for the vehicle that just plugged in and requested a charge.
In practice, the process above will usually take place in a fraction of a second. This makes a power re-allocation feel virtually real time. In reality, there are checks and balances that take place before power is reallocated.
Power management groups, access control groups, and pricing groups are all separate in the system. This means that chargers can be part of the same power management group but different access control or pricing groups. If chargers use a “bill by kWh” pricing profile, power management is already accommodated for, since reducing output power will also reduce the kWh that a vehicle uses.
If chargers use a “bill by time plugged in” pricing profile, then there is no accommodation for power management. End users will be billed the full hourly amount for the entire time they are plugged in. If chargers use a “bill by effective time charging” pricing profile, your dashboard system automatically pro-rates the billing rate based on power management. For example, if a charger bills $2.00 per hour but a power management profile reduces output power by half for a certain time period, the end user will only be billed $1.00 per hour for that time period.
Your dashboard's power management only works with supported EV chargers. Just because an EV charger claims OCPP compliance does not mean it will work with this power management system. If you are unsure if your hardware is supported, please contact Support.
Your CSMS and power management system depends on chargers maintaining an active connection to the internet. The system is designed to accommodate individual chargers dropping offline from time to time, but it cannot do anything to control chargers that remain disconnected for long periods of time.
Your dashboard's power management is a cloud-based system with offline redundancies. We rely on EV chargers being connected to the cloud and communicating to our CSMS most of the time, but the system is designed to accommodate EV chargers that drop offline temporarily.
If all chargers are offline, power management will not work. Cloud-based power management provides more flexibility to adjust the system over time. It also combines load balancing with other CSMS functionalities like monitoring, reporting, billing, or access control.
- Yes. Power management is accessed via the “Power” tab on the navigation sidebar of the dashboard. The electrical infrastructure is represented, including all main panels and any sub-panels for a circuit with chargers with their names/labels, breaker ratings, and maximum continuous load. Charger phase wiring and other power-consuming devices sharing a circuit with chargers (referred to as “unmanaged loads” in the dashboard) are also included.
- If chargers lose internet connection, power limits will still not be exceeded thanks to fallback amperages on individual chargers. Chargers can also be configured to only initiate a new charging session while they are online, ensuring no additional load is added until internet connection is re-established.