3C-i 

APPENDIX 3C. EVALUATION METHODS FOR DIFFERENTIATING 

WALL ADAPTERS WITH CHARGE CONTROL 

TABLE OF CONTENTS 

3C.1 INTRODUCTION .........................................................................................................3C-1

3C.2 DEFINITIONS ...............................................................................................................3C-1

3C.3 SUMMARY OF EVALUATION METHODS .............................................................3C-2

3C.4 DESCRIPTION OF THE EVALUATION METHODS ...............................................3C-2

3C.5 TEST UNITS FOR EVALUATION .............................................................................3C-7

3C.6 RESULTS OF EVALUATION METHODS .................................................................3C-8

3C.7 CONCLUSION ............................................................................................................3C-14

LIST OF TABLES 

Table 3C.1 Units evaluated ....................................................................................................... 3C-7

Table 3C.2 Results of Method 1: Energy Star Inspection ........................................................ 3C-9

Table 3C.3 Results of Method 2: Battery Inspection .............................................................. 3C-10

Table 3C.4 Results of Method 3: Dedicated Operation .......................................................... 3C-11

Table 3C.5 Results of Method 4: No-Battery Operation ........................................................ 3C-12

Table 3C.6 Results of Method 5: Voltage Regulation ............................................................ 3C-13

Table 3C.7 Results of Method 6: No-Load Output Voltage ................................................... 3C-14

Table 3C.8 Summary outcome of different Evaluation Methods for Charge Control............ 3C-15

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3C.1 INTRODUCTION 

The following appendix considers different evaluation methods to identify charge control 

(CC) in wall adapters and hence whether it would be regulated as an external power supply 

(EPS). DOE considers a wall adapter to be an external power supply if it does not contain 

charge control (among other criteria). 

As noted in section 2.2.1.3 of chapter 2 of the preliminary analysis, DOE is considering 

using the Environmental Protection Agency’s Energy Star 2.0 EPS criteria to determine the 

presence of charge control, “DOE would consider a wall adapter with charge control to have 

‘batteries or battery packs that physically attach directly’ and a ‘battery chemistry or type 

selector switch AND an indicator light or state of charge meter.’ ” Throughout this appendix, 

these criteria are referred to as the “Energy Star” criteria.

In addition to the Energy Star criteria, in its framework document (page 38, section 

3.2.4), DOE described three other approaches that could be used to determine charge control in a 

wall adapter unit: 

(1) Short-circuit operation: How the wall adapter performs when a short-circuit load is 

applied. 

(2) Voltage regulation: How the output voltage of the wall adapter varies at different 

active mode loading conditions relative to the nameplate output voltage. 

(3) No-load voltage: How the output voltage of the wall adapter varies at no-load relative 

to the nameplate output voltage. 

 In this appendix, DOE reviews six alternative methods to test for charge control, 

including the above three methods. Section 3C.2 presents definitions used within this appendix. 

All of the evaluation methods are summarized in section 3C.3 whereas section3C.4 presents 

each method in detail. Section 3C.5 presents the units on which DOE performed the evaluation 

methods with the results presented in section 3C.6. Finally, section 3C.7 presents DOE’s 

conclusions. 

3C.2 DEFINITIONS 

Below, DOE provides summary definitions for some important terms used in this 

appendix. Full definitions are available in chapter 3 of the preliminary TSD: 

Application: The application is the main product used by the consumer (e.g. a notebook 

computer). 

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Battery: One or more sealed electrochemical cells that provide power to an application, 

allowing it to operate while disconnected from the AC mains. 

Charge Base: An electrical interface that recharges a battery or battery pack, but that is 

not designed to hold the application itself.

Cradle: An electrical interface between a consumer application and the rest of the battery 

charger designed to hold the application between uses.

Integral Battery: The battery is contained within the consumer application and is not 

removed from the application for charging purposes (Example: Mobile phones). 

Non-Integral Battery: The battery is removed from the application for charging purposes 

(Example: universal battery charger). 

Wall Adapter: Any external power adapter that connects a consumer application to the 

household electric supply (AC mains). 

3C.3 SUMMARY OF EVALUATION METHODS 

(1) Energy Star inspection: Visually inspect the wall adapter for Energy Star criteria 

(2) Battery inspection: Characterize the type of batteries in the application 

(3) Dedicated operation: Operate the application and charge the battery simultaneously 

(4) No-battery operation: Operate the application with the wall adapter but without the battery 

(5) Voltage regulation: Evaluate output voltage variation with load 

(6) No-load output voltage: Evaluate output voltage variation in no-load mode 

(7) Voltage source operation: Operate the application using a pure voltage source 

3C.4 DESCRIPTION OF THE EVALUATION METHODS 

This section of the appendix describes the specific steps involved with the evaluation 

methods under consideration. Each method consists of steps followed by a final evaluation. The 

steps are questions, procedures, measurements, or calculations. For the steps that are questions, 

an answer of “Yes” corresponds to a logical value of TRUE and an answer of “No” corresponds 

to a logical value of FALSE. The final evaluation of charge control is a logical statement that 

operates on the steps using “AND”, “OR” and “NOT” operators. An evaluation that returns a 

value of “TRUE” indicates that a wall adapter has charge control and would not be regulated as 

an EPS. In some cases, not all steps are used in the final evaluation; however, DOE includes 

them to allow for comment from interested parties. 

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(1) Method 1: Energy Star inspection: 

In this method the wall adapter is evaluated by visual inspection for the Energy Star criteria. 

Steps:

1A = Does the wall adapter have batteries or battery packs that physically attach 

directly?a

1B = Does the wall adapter have a battery chemistry switch? 

1C = Does the wall adapter have a type selector switch? 

1D = Does the wall adapter have an indicator light? 

1E = Does the wall adapter have a state of charge meter? 

Evaluation: 

 CC1 = {(1A) OR {[(1B) OR (1C)] AND [(1D) OR (1E)]}} 

If a wall adapter either has “batteries or battery packs that physically attach directly” or has 

“a battery chemistry or a type selector switch AND an indicator light or a state of charge meter”

then wall adapter has charge control. 

(2) Method 2: Battery inspection: 

In this method, the wall adapter is evaluated by visually inspecting its functions and what it is 

packaged with. 

Steps:

2A = Is the wall adapter packaged with the application? 

2B = Is the wall adapter or the application packaged with a battery? 

2C = Is the battery integral? 

2D = Is the wall adapter packaged with a cradle? 

2E = Is the wall adapter packaged with a charging base? 

2F = Does the wall adapter have a battery chemistry? 

2G = Does the wall adapter have a battery type selector switch? 

Evaluation: 

CC2 = {[(2A) AND (2B)] AND [(2E) OR (2F) OR (2G)]} 

 

a

An adapter that "physically attaches directly" is one with a galvanic connection to the battery. An example would be a 

universal battery charger or a power tool battery charging base, where the battery terminals physically touch the output of the 

wall adapter. If the adapter connects directly to the application rather than the battery itself, then it would not be classified as 

"physically attaching directly" (e.g. notebook computer adapters.)

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If the wall adapter is packaged with an application and a battery, and is either packaged with 

a charging base, has a battery chemistry switch or has a battery type selector switch, then wall 

adapter has charge control. Steps 2C and 2D are not used in this evaluation. 

(3) Method 3: Dedicated operation: 

In this method the wall adapter is evaluated based on its ability to charge an empty battery. 

The evaluation is carried out by operating the application and attempting to charge the battery 

simultaneously. 

Steps:

3A = Does the application have a battery? 

3B = Disconnect the wall adapter from the application. Operate the application 

using only the battery until the application stops functioning due to the 

battery fully discharging. 

3C = Connect the wall adapter to mains and to the application. Immediately 

attempt to operate the application. 

3D = Does the application operate? 

3E = Keep the application connected to mains via the wall adapter. Operate the 

application for 10 minutes.

3F = Disconnect the wall adapter from the application and operate the 

application only with the battery. 

3G = Can the battery now power the application? 

Evaluation:

CC3 = {(3A) AND ([NOT (3D)] OR [NOT (3G)])} 

If the application has batteries and does not operate when the application is immediately 

connected to the wall adapter with a fully discharged battery or when the wall adapter is 

disconnected after 10 minutes, then wall adapter has charge control. 

Steps 3B, 3C, 3E and 3F are not used in this evaluation. 

(4) Method 4: No-battery operation: 

In this method the wall adapter is evaluated by operating the application with the wall 

adapter but without the battery to check whether the application is fully operational. An 

application is considered to be fully operational if it can perform all functions that the application 

would perform were the battery connected, other than battery charging. 

Steps:

4A = Does the application have a battery? 

4B = Is it possible to remove the battery from the application without damaging 

the application? 

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4C = If 4B is TRUE then remove the battery from the application and connect 

the application to the wall adapter and connect the wall adapter to the 

mains. 

4D = Is the application fully operational? 

4E = If the application is not fully operational, does is it operate at all? (e.g., 

LED indicator light). List the functions that operate.

Evaluation:

CC4 = {(4A) AND (4B) AND [NOT (4D)]}

If the application has a battery which can be removed from the application without damaging 

the application and the application is not fully operational when it is connected to the mains via 

the wall adapter after removing the battery, then wall adapter has charge control. Steps 4C and 

4E are not used in this evaluation. 

(5) Method 5: Voltage regulation: 

In this method the wall adapter is evaluated by calculating output resistance. 

Steps:

5A = Measure the output voltage (V100%) when the current is at 100% of its 

nameplate output current. 

5B = Measure the output current (I100%), when the current is at 100% of its 

nameplate output current. 

5C = Measure the output voltage (V25%) when the current is limited at 25% of its 

nameplate output current. 

5D = Measure the output current (I25%), when the current is limited at 25% of its 

nameplate output current. 

5E = Calculate output resistance, Rout by using the formula: 

 

25% 100%

25% 100%

I I

V V

Rout

Evaluation:

CC5 = {5E > 1 ohm}

According to voltage regulation method, if a wall adapter’s output resistance, Rout, is greater 

than 1 ohm then the wall adapter has charge control. Steps 5A through 5D are not directly used 

in the evaluation. 

(6) Method 6: No-load output voltage: 

This method is evaluated by calculating the output voltage variation between the output 

voltage at no-load mode and the nameplate output voltage. 

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Steps:

6A = Measure the output voltage (V0%), when there is no-load attached to the 

wall adapter. 

6B = Note the nameplate output voltage (Vnameplate).

6C = Calculate Vvariation by using the formula: 

 

nameplate

iation V

V

V

0%

var

Evaluation:

CC6 = {6C > 1.1}

According to no-load output voltage method, if the calculated Vvariation of the wall adapter is 

greater than 1.1, that is, if the voltage variation between nameplate data and no-load mode is 

more than 10%, then wall adapter has charge control. 

Steps 6A and 6B are not directly used in the evaluation. 

(7) Method 7: Voltage source operation: 

This method is evaluated by operating the application using a pure voltage source and 

inspecting whether the application functions. 

Steps:

7A = Does the application have a battery? 

7B = Discharge the battery fully by operating the application without the wall 

adapter until the application stops operating because the battery is 

completely discharged. 

7C = Operate the application with the wall adapter using a pure voltage source 

with the output voltage set to the nameplate output voltage of the wall 

adapter. 

7D = Does the application operate? 

Evaluation:

CC7 = {(7A) AND [NOT (7D)]}

If the application has a battery and cannot operate with the wall adapter connected to a pure 

voltage source and with a fully discharged battery, then wall adapter has charge control. Steps 

7B and 7C are not used in the evaluation. 

This method was not performed on test units and hence, DOE seeks stakeholder comment on 

this method. 

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3C.5 TEST UNITS FOR EVALUATION 

DOE selected the test units from a variety of applications, each with a wall adapter and a 

battery. In addition, DOE chose several control units (#901, #904, #907, #910, #913, and #916) 

that do not use batteries and therefore have no charge control. These control units are used to 

verify the evaluation outcome. Table 3C.1shows the list of units that were evaluated: 

Table 3C.1 Units evaluated 

Unit 

#

Application Type Control 

Units

Features 

Accompanying Wall 

Adapter

Wall 

Adapter 

Nameplate 

Output 

Power [W]

Wall Adapter 

Average ActiveMode Efficiency 

[%]

662 Cordless Phone Base Station 

with Answering Machine No Application, Integral Battery, Cradle 2.4 63.1%

663 Cordless Phone Base Station 

with Answering Machine No Application, Integral Battery, Cradle 2.4 55.4%

623 Mobile Phones No None *4.3 36.4%

697 Mobile Phones No Application, Integral 

Battery 3.8 64.3%

696 Mobile Phones No Application, Integral 

Battery 3.6 66.0%

686 Mobile Phones No Application, Integral 

Battery 2.8 64.1%

632 Notebook Computers No Application, Integral 

Battery 64.8 87.6%

858 Notebook Computers No None *55.8 83.5%

857 Notebook Computers No None *54.0 87.3%

670 Portable DVD Players No Application, Integral 

Battery 16.2 78.4%

698 Portable Video Game System No Application, Integral 

Battery 4.1 69.4%

901 Computer Speakers Yes Application 18.0 79.8%

907 Digital Photo Frames Yes Application 18.0 86.1%

904 Digital Photo Frames Yes Application 18.0 85.8%

910 Digital Photo Frames Yes Application 10.0 70.1%

913 External Hard Drives Yes Application 18.0 85.7%

916 LAN Equipment Yes Application 18.0 86.6%

*

 These units are replacement units that were not packaged with the original application. 

DOE chose the above test units which were available with all the components from the 

DOE test laboratory and were not destroyed due to other tests conducted previously. 

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3C.6 RESULTS OF EVALUATION METHODS 

Results for the evaluation methods, discussed in Section 3C.4, are given in detail in this 

section. Method 7 was not conducted by DOE at this time but remains under consideration. In 

the following tables the “Yes” and “No” answers to questions are shown as “T” (TRUE) and “F” 

(FALSE), respectively. An entry of “-” corresponds to an answer of Not Applicable. 

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As shown in Table 3C.2, results from method 1 show that none of the 17 wall adapters 

tested, have charge control. Though two of the notebook computers had indicator lights, they do 

not meet the Energy Star criteria and hence do not contain charge control. 

Table 3C.2 Results of Method 1: Energy Star Inspection 

Unit Application Type 1A 1B 1C 1D 1E CC 1

662 Cordless Phone Base Station with 

Answering Machine F F F F F F

663 Cordless Phone Base Station with 

Answering Machine F F F F F F

623 Mobile Phones F F F F F F

697 Mobile Phones F F F F F F

696 Mobile Phones F F F F F F

686 Mobile Phones F F F F F F

632 Notebook Computers F F F F F F

858 Notebook Computers F F F T F F

857 Notebook Computers F F F T F F

670 Portable DVD Players F F F F F F

698 Portable Video Gaming Sys. F F F F F F

901 Computer Speakers F F F F F F

907 Digital Photo Frames F F F F F F

904 Digital Photo Frames F F F F F F

910 Digital Photo Frames F F F F F F

913 External hard drives F F F F F F

916 LAN Equipment F F F F F F

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As shown in Table 3C.3, results from method 2, also show that none of the wall adapters 

tested have charge control, similar to the results from method 1. 

Table 3C.3 Results of Method 2: Battery Inspection 

Unit Application 2A 2B 2C 2D 2E 2F 2G CC 2

662 Cordless Phone Base Station with 

Answering Machine T T T T F F F F

663 Cordless Phone Base Station with 

Answering Machine T T T T F F F F

623 Mobile Phones F F - F F F F F

697 Mobile Phones T T T F F F F F

696 Mobile Phones T T T F F F F F

686 Mobile Phones T T T F F F F F

632 Notebook Computers T T T F F F F F

858 Notebook Computers F F - F F F F F

857 Notebook Computers F F - F F F F F

670 Portable DVD Players T T T F F F F F

698 Portable Video Gaming Sys. T T T F F F F F

901 Computer Speakers T F - F F F F F

907 Digital Photo Frames T F - F F F F F

904 Digital Photo Frames T F - F F F F F

910 Digital Photo Frames T F - F F F F F

913 External hard drives T F - F F F F F

916 LAN Equipment T F - F F F F F

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As shown in Table 3C.4, results from method 3 show that out of the seventeen test units, 

the wall adapters used for both the cordless phones have charge control. 

Table 3C.4 Results of Method 3: Dedicated Operation 

Unit Application 3A 3D 3G CC 3

662 Cordless Phone Base Station with 

Answering Machine T F F T

663 Cordless Phone Base Station with 

Answering Machine T F F T

623 Mobile Phones F - - F

697 Mobile Phones T T T F

696 Mobile Phones T T T F

686 Mobile Phones T T T F

632 Notebook Computers T T T F

858 Notebook Computers F - - F

857 Notebook Computers F - - F

670 Portable DVD Players T T T F

698 Portable Video Gaming Sys. T T T F

901 Computer Speakers F - - F

907 Digital Photo Frames F - - F

904 Digital Photo Frames F - - F

910 Digital Photo Frames F - - F

913 External hard drives F - - F

916 LAN Equipment F - - F

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As shown in Table 3C.5, results from method 4 show that six wall adapters have charge 

control. Specifically, wall adapters for two of two cordless phones, three of four mobile phones 

and one of one portable video gaming system have charge control. 

Table 3C.5 Results of Method 4: No-Battery Operation 

Unit Application 4A 4B 4D 4E CC 4

662 Cordless Phone Base Station 

with Answering Machine T T F

Display states that the battery level is low. 

The entire cradle is functional T

663 Cordless Phone Base Station 

with Answering Machine T T F

Charge light on. 

Displays "Warning Check Battery" T

623 Mobile Phones F - - F

697 Mobile Phones T T F Screen lights dimly T

696 Mobile Phones T T F Displays "battery is required" T

686 Mobile Phones T T F Displays "Unable to charge" T

632 Notebook Computers T T T F

858 Notebook Computers F - - F

857 Notebook Computers F - - F

670 Portable DVD Players T T T F

698 Portable Video Gaming Sys. T T F Indicator light blinks T

901 Computer Speakers F - - F

907 Digital Photo Frames F - - F

904 Digital Photo Frames F - - F

910 Digital Photo Frames F - - F

913 External hard drives F - - F

916 LAN Equipment F - - F

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As shown in Table 3C.6, results from method 5 show that three wall adapters have charge 

control. This method identified charge control in wall adapters for both cordless phones and one 

of four mobile phones. The units that have charge control had output resistance ranging from 

7.77 to 13.07 ohms whereas the output resistance of the units without charge control range from 

0.0 to 0.37 ohms. Unit # 696 had the same output voltage for both the loading level, hence 0 ohm 

output resistance. 

Table 3C.6 Results of Method 5: Voltage Regulation 

Unit Application Type

V100% 

(V)

(5A)

I100% 

(A)

(5B)

V25% 

(V)

(5C)

I25% 

(A)

(5D)

R 

(ohm)

(5E)

CC 5

662

Cordless Phone Base Station with Answering 

Machine 5.96 0.40 8.29 0.10 7.77 T

663

Cordless Phone Base Station with Answering 

Machine 5.92 0.20 7.88 0.05 13.07 T

623 Mobile Phones 0.02 0.85 5.04 0.21 7.87 T

697 Mobile Phones 5.00 0.75 5.10 0.19 0.18 F

696 Mobile Phones 5.15 0.70 5.15 0.18 0.00 F

686 Mobile Phones 5.06 0.55 5.01 0.14 0.12 F

632 Notebook Computers 19.67 3.50 19.96 0.88 0.11 F

858 Notebook Computers 14.74 3.72 15.08 0.93 0.12 F

857 Notebook Computers 15.65 3.60 15.94 0.90 0.11 F

670 Portable DVD Players 8.83 1.80 9.09 0.45 0.19 F

698 Portable Video Gaming Sys. 4.64 0.90 4.89 0.23 0.37 F

901 Computer Speakers 11.87 1.50 12.00 0.38 0.12 F

907 Digital Photo Frames 11.85 1.50 12.12 0.38 0.24 F

904 Digital Photo Frames 11.87 1.50 12.13 0.38 0.23 F

910 Digital Photo Frames 4.78 2.00 5.04 0.50 0.17 F

913 External hard drives 12.04 1.50 12.20 0.38 0.14 F

916 LAN Equipment 11.98 1.50 12.16 0.38 0.16 F

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As shown in Table 3C.7, results from method 6 show that two wall adapters have charge 

control. Specifically, both wall adapters for cordless phones have charge control. Voltage 

variation for the two units is 1.53 and 1.64 whereas the voltage variation for the other units 

varies from 1.00 to 1.08. 

Table 3C.7 Results of Method 6: No-Load Output Voltage 

Unit Application Type V0% (V)

(6A)

Vnameplate (V)

(6B)

VVariation

(6C) CC6?

662 Cordless Phone Base Station 

with Answering Machine 9.84 6.00 1.64 T

663 Cordless Phone Base Station 

with Answering Machine 9.20 6.00 1.53 T

623 Mobile Phones 5.10 5.00 1.02 F

697 Mobile Phones 5.13 5.00 1.03 F

696 Mobile Phones 5.15 5.10 1.01 F

686 Mobile Phones 5.07 5.00 1.01 F

632 Notebook Computers 20.06 18.50 1.08 F

858 Notebook Computers 15.08 15.00 1.01 F

857 Notebook Computers 16.00 15.00 1.07 F

670 Portable DVD Players 9.18 9.00 1.02 F

698 Portable Video Gaming Sys. 4.97 4.60 1.08 F

901 Computer Speakers 12.04 12.00 1.00 F

907 Digital Photo Frames 12.19 12.00 1.02 F

904 Digital Photo Frames 12.20 12.00 1.02 F

910 Digital Photo Frames 5.13 5.00 1.03 F

913 External hard drives 12.25 12.00 1.02 F

916 LAN Equipment 12.21 12.00 1.02 F

3C.7 CONCLUSION 

In summary, different evaluation methods yielded different outcomes in identifying 

charge control in a wall adapter, as shown in Table 3C.8.

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Table 3C.8 Summary Outcome of Different Evaluation Methods for Charge Control

Unit Application Type CC 1 CC 2 CC 3 CC 4 CC 5 CC6

662 Cordless Phone Base Station 

with Answering Machine F F T T T T

663 Cordless Phone Base Station 

with Answering Machine F F T T T T

623 Mobile Phones F F F F T F

697 Mobile Phones F F F T F F

696 Mobile Phones F F F T F F

686 Mobile Phones F F F T F F

632 Notebook Computers F F F F F F

858 Notebook Computers F F F F F F

857 Notebook Computers F F F F F F

670 Portable DVD Players F F F F F F

698 Portable Video Game System F F F T F F

901 Computer Speakers F F F F F F

907 Digital Photo Frames F F F F F F

904 Digital Photo Frames F F F F F F

910 Digital Photo Frames F F F F F F

913 External Hard Drives F F F F F F

916 LAN Equipment F F F F F F

According to method 1, Energy Star criteria, and method 2, battery inspection, none of 

the wall adapters had charge control. Both method 3 and method 6, dedicated operation and noload output voltage respectively, found that both wall adapters for cordless phones to had charge 

control. Method 4 found the most wall adapters to have charge control: wall adapters for both 

cordless phones, three mobile phones, and a portable video game system. Method 5, voltage 

regulation, found both wall adapters for cordless phones to have charge control, as well as a wall 

adapter for a mobile phone. The last six test units in Table 3C-8 are control units because their 

applications do not use batteries. All of the six evaluation methods indicate that the control units’

wall adapters did not have charge control. 

DOE seeks comments from stakeholders on all of the evaluation methods and results 

presented in this appendix, especially to comment on whether any one or more of the methods in 

combination can be used to determine charge control more effectively than the current test 

according to Energy Star criteria. 

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