California Puts Battery Chargers on an Energy Consumption Diet
January 17, 2012 - The California Energy Commission (CEC) has started off 2012 all charged up and ready to reduce battery charger system (BCS) energy waste.
On January 12th, the Commissioners voted to adopt limits (proposed in last December's 15-day Language) as amendments to the Appliance Efficiency Regulations (Title 20). That makes the CEC the world's first government agency to mandate minimum requirements for BCSs efficiency, ranging from under a watt to over 2 kW. This standard covers just about every system that plugs in the wall and charges batteries including cell phones, laptop and tablet computers, power tools, personal care products, UPSs, and non-highway vehicles (i.e. forklifts and golf carts).
The CEC has been working since April 2008 to develop a cost-effective and technically feasible BCS regulation, with multiple stakeholder meetings attended by utility companies, environmental organizations, manufacturers, and consumer groups (and me). But some stakeholders question if another California-only efficiency standard is really necessary. The commission believes it is, considering that of the 8,000 GWh/year that BCSs currently consume in the state, only 2,000 GWh of electricity is actually delivered to the battery. And, even if a federal government BCS standard is published in the future, the state would be saving energy for approximately 18 months before the federal one becomes effective.
So, how difficult is it to cost-effectively meet the CEC standard when it begins kicking in, staring February 2013? Probably not that difficult, based on a report, submitted to the CEC by utilities, that says there are currently a large number of BCSs available on the market that already meet the standard's levels. The report also determined that there are multiple technologies used in BCSs that cheaply and effectively reduce energy consumption, addressing fears from manufacturers that they could be forced to use proprietary methods to comply with the standard.
The CEC believes that focusing on two specific areas - AC-DC power conversion and maintenance mode - can lead to conformance. Since AC-DC power conversion plays a key role in overall system efficiency, changing from a linear to an efficient switching power conversion circuit is an easy and cost-effective way to improve power consumption. The CEC also found that the least efficient chargers on the market don't detect when a battery is fully charged and continue to provide unnecessary power to the battery. By shutting off the continuous flow of electricity to the fully charged battery and providing a low maintenance charge not only prevents wasting energy but also avoids damaging the battery.
As a final note, while there were concerns raised at last week's meeting by some manufacturers that this standard, if approved, could keep some products off California store shelves and stall innovation, there were also comments by efficiency alliances and agencies (as far away as Australia) who said that they would consider adopting the California BCS standard in their regions.
Following is a summary of the efficiency requirements.
The BCSs are divided into four categories:
- Small Battery Charger Systems (SBCS): ≤ 2 kW, including golf cart chargers regardless of output power
- Inductive Charger Systems –magnetic or electric induction power transfer SBCS
- Battery Backup Chargers – SBCS that provides power to an end use product in a power outage
- Large Battery Charger Systems (LBCS): > 2 kW output power
The SBCS standard targets energy consumption over a 24 hour period including charge mode. The LBCS standard targets power conversion efficiency and charge return factor (CRF).
Table 1 below shows the limits that consumer SBCSs manufactured on or after February 1, 2013 must meet. Non-consumer SBCS must comply after January 1, 2017.
| Performance Parameter | Standard |
|---|---|
| Maximum 24 hour charge and maintenance energy (Wh) (Eb = capacity of all batteries in ports and N = number of charger ports) | For Eb of 2.5 Wh or less: 16 × N |
| For Eb greater than 2.5 Wh and less than or equal to 100 Wh: 12 x N +1.6Eb | |
| For Eb greater than 100 Wh and less than or equal to 1000 Wh: 22 x N+1.5Eb | |
| For Eb greater than 1000 Wh: 36.4 x N +1.486Eb | |
| Maintenance Mode Power and No Battery Mode Power (W) (Eb = capacity of all batteries in ports and N = number of charger ports) | The sum of maintenance mode power and no battery mode power must be less than or equal to: 1x N+0.0021xEb Watts |
Additionally:
- Inductive Charger Systems (built on/after February 1, 2013) must either meet the SBCS requirements above OR use < 1 W in maintenance mode and < 1 W in no battery mode and average ≤ 1 W/hr over the charge and maintenance test
- Battery Backup and UPSs (built on/after February 1, 2013 for consumer products and January 1, 2017 for all others) must consume ≤ 0.8+0.0021 x Eb W in maintenance mode.
The requirements for LBCS manufactured on/after January 1, 2014 are shown below.
| Performance Parameter | Standard | |
|---|---|---|
| Charge Return Factor (CRF) | 100 percent, 80 percent depth of discharge | CRF≤ 1.10 |
| 40 percent depth of discharge | CRF ≤ 1.15 13 | |
| Power Conversion Efficiency | Greater than or equal to: 89 percent | |
| Power Factor | Greater than or equal to: 0.90 | |
| Maintenance Mode Power (Eb = battery capacity of tested battery) | Less than or equal to: 10 + 0.0012Eb W | |
| No Battery Mode Power | Less than or equal to: 10 W | |
For a copy of the approved BCS standard wording (15-day Language), go to:
http://www.energy.ca.gov/2011publications/CEC-400-2011-005/CEC-400-2011-005-15-DAY.pdf
A copy of Frequently Asked Questions regarding this standard is available at:
http://www.energy.ca.gov/appliances/battery_chargers/documents/Chargers_FAQ.pdf
MrGreen
