The document summarizes an investigation into the applicability of the U.S. Department of Energy's battery charger test procedure for measuring the energy performance of wireless battery chargers available in Canada. It recommends clarifying the test procedure in four ways but finds that the overall framework is appropriate. Testing of one wireless charger found efficiency may decrease by 5% if the battery is offset slightly from the center position.

1. PAGE 1 | Wireless BCs Test Procedure Recommendations
MEMORANDUM
To: Augustine Orumwense and Marc Ostrowski, Natural Resources Canada
From: Suzanne Foster Porter, Dave Denkenberger, PhD, David Thomsen, Brian Spak, Ecova
Date: March 28, 2014
Subject: Wireless Battery Charger Test Procedure Investigation and Recommendations
___________________________________________________________________
SUMMARY
Our review of the U.S. Department of Energy’s battery charger test procedure concluded that the test
procedure accommodates wireless battery chargers currently available in Canada. Our market research
revealed that only near-field wireless battery chargers (i.e. products in which the charger and the battery
are in physical contact) are available in Canadian retail outlets. We recommend a few clarifications to the
test procedure to improve clarity and ensure repeatability. In no way do these changes affect the overall
test procedure approach or framework, timing, equipment required or other technical elements of the test
procedure. Recommended clarifications include:
 specifying language regarding rest of wirelessly charged batteries
 broadening the definition of cradle to explicitly include wireless battery chargers
 ensuring testing on an electrically nonconductive surface
 guiding language for the placement of the wireless battery on the charger
In addition to the clarifications that we recommend that NRCan pursue, this memo discusses some
additional issues related to the test procedure and its applicability to wireless battery chargers not
currently on the market. While NRCan could amend the test procedure to resolve these issues, we do not
recommend doing so at this time, because the changes are non-substantive or we lack data to support
the change. These include testing the battery at the edge of the physical charging range and including a
radiofrequency shielded box. Additionally, in the appendix, we list further opportunities to improve clarity
of the the test procedure for all battery chargers, wireless and wired, that we uncovered while conducting
our investigation.
INTRODUCTION AND OBJECTIVES
“Wireless power products,” which provide power to a product without a wired connection, have recently
entered the market. The enabling technology differs depending on the device, but depends on

2. PAGE 2 | Wireless BCs Test Procedure Recommendations
electrodynamics, electrostatics, microwaves or lasers. Three broad categories of wireless power
technology exist: i) far field or radio frequency (i.e. the charger and the battery are a few meters apart); ii)
mid-range or far edge inductive coupling (i.e. the charger and the battery are a few centimeters apart);
and iii) near field (i.e. the charger and the battery are in physical contact). The scope of this project was
limited to near-field inductive devices, the only wireless power products commercially available in Canada
in late 2013.
This project had two objectives: to survey wireless power products in the Canadian market and to
determine the applicability of the United States Department of Energy’s (DOE) external power supplies
and battery charger test procedure for measuring the energy performance of wireless power devices. This
memo aims to support NRCan’s participation in the Canadian Standard Association’s efforts related to the
development of external power supplies and battery chargers test procedures.
MARKET SURVEY, PRODUCT SELECTION, AND METHODOLOGY
To understand the market of near-field inductive devices, we researched available products through
identification of the common products available in online Canadian store catalogs and telephone
conversations with in-store employees to determine the stock at several major retailers in the Ottawa
region. The survey uncovered two trends: First, near field inductive charging devices available in Canada
largely cater to smart phones and game console controller devices. Secondly, these chargers are
primarily offered online (store representatives recommended buying wireless chargers online).
The two devices we chose to purchase represent the range of products in the market, ensuring that our
evaluation of the applicability of the DOE test procedure represented current products. Of the available
devices, we chose the Duracell Powermat pad compatible with mobile devices and inductive batteries
from Amazon.CA1
and the dreamGear DGWII-3116 Wii remote charger, capable of charging four remote
game controllers for the Nintendo game console, Wii. The dreamGear device was available from
FutureShop.com, BestBuy.CA and Amazon.CA. Figure 1 shows the two chargers. Additional batteries, a
cell phone for the Powermat and Wii controllers for the dreamGear were required to test the products
according to the DOE test procedure. Table 1 lists all items purchased.
1
This Powermat is capable of charging two batteries at once.

3. PAGE 3 | Wireless BCs Test Procedure Recommendations
Figure 1: Duracell Powermat (left) and dreamGear Wii Remote Charger (right)
The Duracell Powermat is compatible with smart phones with wireless charging cases and specially
designed inductive batteries. As a multi-capacity, multi-voltage, and multi-port battery charger, the
Powermat requires three tests: lowest voltage (lowest charge capacity, one port), highest voltage (highest
charge capacity, one port), and highest energy capacity (all ports).
Table 1
Item Description Category
dreamGear Wii remote charger for 4 remotes (DGWII-3116), four NiMH rechargeable
battery packs
Inductive Charging Mat,
Batteries
Rock Candy Nintendo Wii Remote Controller ( Model # PL8560GR) Wii Remote
Nintendo Wii U Remote Plus (WebID # 10227199) Wii Remote
Wii Remote Plus Controller (Model # RVLAWRPA) Wii Remote
Collective Minds Nintendo Wii U Motion Plus Deluxe Kit (Model # CM00059) Wii Remote
Duracell Powermat for two devices kit (Model # CSA4B1), iPhone 4 wireless charging
case and Duracell GoPower Day Trip Battery (5V, 1850 mAh)
Inductive Charging Mat,
Battery, Phone Charging
Case
Duracell GoPower Long Haul Battery (5V, 8800 mAh) x3 Battery (x3)
Apple iPhone 4 (A1349)- integrated phone battery (3.7V, 1420 mAh) Smart Phone
* An additional Duracell Powermat for 3 devices was purchased for comparison
ENGINEERING INVESTIGATION
I.Methodology for investigation
Based on the understanding of the battery charger test procedure and the fundamental science behind
wireless battery chargers, we looked in particular at two potential issues that could affect the applicability
of the test procedure to these wireless charger systems: battery selection and displacement. We also
conducted a thorough review of the entire test procedure language with the physical products in hand to
understand any other possible issues not in our original hypothesis. To determine the suitability of the

4. PAGE 4 | Wireless BCs Test Procedure Recommendations
DOE battery charger test procedure, we conducted a physical inspection of the selected products and
investigated the performance of one of the products.
II.Battery Selection
After we determined the chargers to purchase, we used the DOE test procedure to select the batteries.
We first determined the range of possible batteries in order to understand the number of tests required.
Then, these individual tests dictated which batteries to purchase. This process is identical for other
chargers sold without their batteries (car battery chargers, power tool chargers, some chargers capable of
charging many standard types of rechargeable batteries that replace primary batteries (AA, AAA, C and
D). Wireless products have battery selection requirements similar to many wired battery charger products
already covered by the test procedure. The test procedure’s existing requirements for battery selection
apply to wireless battery chargers just as they do for wired chargers.
III.Displacement
We chose the Duracell Powermat for further engineering investigation because it allowed greater freedom
of movement of the products being charged than the dreamGear2
remote charger; we hypothesized that
this freedom of movement would impact the efficiency of the product. We conducted a performance
evaluation with the largest battery to provide the greatest resolution of the potential for differing efficiency
based on the placement of the battery on the charger. The battery was charged and discharged both with
the magnets and coils aligned (on center) and offset at 3 mm from center. Table 2 shows that the 24-hour
charger efficiency falls by about five percent when the charger is on the edge of the viable charging range
(3 mm offset from center). We found that the results were repeatable to within one percent.
Table 2
Location
Energy (Whrs)
Charging
Energy (Whrs)
Discharging
24 hour
efficiency
2
The dreamGear Wii charger, able to charge up to four Wii remote devices, had designated grooves on the surface
that limited orientation of the battery when charging, significantly limiting the different battery layout options and
effectively preventing battery displacement (see
Figure 1).

5. PAGE 5 | Wireless BCs Test Procedure Recommendations
On center 69 34 49%
Offset 3 mm 73 34 46%
From this investigation, we recommend that the test procedure include clarification language that states
the battery shall be placed in the specified location, or barring that, placed according to the
manufacturer’s instructions (see Table 3).
As products evolve and new products are introduced, it is possible that an additional test to understand
the specific efficiency impact of placing the battery in different locations on the charger could be
appropriate (see Table 4). While this additional test would provide more data, it would also increase the
testing burden. In addition, it is unclear to what degree, if any, the difference observed in the lab would
manifest itself in the field because strong magnets present in some current products may automatically
align the coils. Indeed, the design of the Duracell Powermat did not allow displacement of the battery to
be offset greater than three mm.
IV.General investigation
We concluded in our assessment of Canadian wireless products that the market and technology of
wireless battery chargers are very similar to wired chargers. The wireless products are targeted for
consumer use; they are set up and operate similarly to other consumer battery chargers. The main
difference is that they have a receiver and a transmitter instead of a direct electrical connection to
transmit power from the charger to the battery. This affects efficiency and functionality, but it does not
substantially change the way they need to be tested. As a result, the general approach, the timing, the
instrumentation, etc. in the test procedure were all found to be appropriate.
We found a few additional opportunities for clarification to help ensure repeatability of the test approach to
these chargers (see Table 3):
1. adding a definition of wireless battery chargers,
2. adding language regarding rest of wirelessly charged batteries,
3. broadening the definition of cradle to explicitly include wireless battery chargers, and
4. ensuring testing on an electrically nonconductive surface.
Table 3
DOE Test
Procedure
section
Problem/issue Possible solution/resolution
2.8; 2.9 No definition of wireless battery charger A wireless battery charger is a battery

6. PAGE 6 | Wireless BCs Test Procedure Recommendations
charger that transfers charging energy via a
non-conductive route.
2.9 This section says “Battery rest period is a
period of time between discharge and charge
or between charge and discharge, during
which the battery is resting in an open-circuit
state in ambient air.” The term open circuit
does not apply for wireless chargers
considered in this study.
Change to “Battery rest period is a period of
time between discharge and charge or
between charge and discharge, during
which the battery is resting in ambient air in
an open-circuit state for conductive
chargers and outside the viable charging
range for wireless chargers.”
2.11 Definition is not clear whether an inductive
pad is considered a cradle.
Change “electrical interface” to “conductive
or inductive interface” to clarify that an
inductive pad could be considered a cradle.
3.3 “The UUT shall be conditioned, rested, and
tested on a thermally non-conductive
surface.” Electrical conductivity of the surface
could affect a wireless charger.
Replace with “The UUT shall be
conditioned, rested, and tested on a
thermally and electrically non-conductive
surface.”
5.6 c. (5) refers to placing in cradle “If the charger does not have a specific
physical location required for the battery on
the charger, place battery according to
manufacturer’s instructions.”
Lastly, our research identified an additional, potential issue with the test procedure. While we do not
recommend changes to the test procedure to address this issue at this time, it is worth monitoring going
forward. The test procedure could require the use of a radiofrequency (RF) shield box to prevent stray RF
signals from affecting wireless charger operation. For wireless small network equipment, the ENERGY
STAR test procedure specifies the use of an RF shielded box. While the science suggests that the use of
such a shield may be justified for wireless battery chargers, it would increase the testing burden and we
have not measured the impact of stray RF signals on product performance during the test procedure.
Table 4
DOE Test
Procedure
section
Problem/issue Possible solution/resolution
5.6 c. (5) refers to placing in
cradle
“If the charger is wireless, place battery according to
manufacturer’s instructions for the required tests. In addition, if
the charger is wireless, do one additional test which is a
repeat of the required test with the greatest energy capacity
with the battery on the edge of the viable charging range.”
5.6 Stray RF signals could affect
wireless charger operation.
“If the battery charger is wireless, place the UUT inside a
shielded enclosure large enough to fit the UUT without contact
with enclosure walls (or floor – elevate UUT with a thermally
and electrically non-conductive slab). The enclosure must
have sufficient RF absorbing material lining all inside surfaces
and also have sufficient feed-throughs to service the UUT.”

7. PAGE 7 | Wireless BCs Test Procedure Recommendations
V.Conclusion
Our investigation of the US DOE test procedure determined that the test procedure as currently written
applies to wireless power products. A reasonable reading of the test procedure and a good faith approach
by a laboratory certified to test battery chargers should produce a fair and accurate rating of the energy
consumption of a given wireless battery charger. We recommend amending the test procedure in a few
instances to improve clarity and ensure repeatability, but even absent these changes, the test procedure
currently applies to wireless products available for retail purchase in Canada.
APPENDIX
Through our investigation, we discovered that the test procedure could be amended to improve overall
clarity for the testing of all battery chargers, both conventional and wireless. Table 5 summarizes these
recommendations.
Table 5
DOE Test
Procedure
section
Problem/issue Possible solution/resolution
4.5, 5.3,
Table 5.2
“C” is ambiguous Replace “C” with “C-rate”
5.2 This section talks about indicators located
in the battery charger that show if the
battery is fully charged. What if the
indicators are located in the specific battery
used by the charger?
Replace “If the battery charger has an indicator
to show that the battery is fully charged” with “If
the UUT, battery charger, or battery has an
indicator to show that the battery is fully charged”
5.8 In part C.2 of this section it reads “Set the
battery analyzer for a constant discharger
current of 0.2 ˚C”
Replace “0.2˚C” with “0.2 C-rate based on
labeled capacity (or experimentally determined
capacity if there is no capacity label)”