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Battery Capacity and Charge Mode Battery Charger Power Consumption June 21, 2005 Chris Calwell [email protected] 970-259-6801 x301 Director of Policy and Research Ecos Consulting

Battery Capacity and Charge Mode Battery Charger …...Battery Capacity and Charge Mode Battery Charger Power Consumption June 21, 2005 Chris Calwell [email protected] 970-259-6801

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Battery Capacity and Charge Mode Battery Charger

Power Consumption

June 21, 2005

Chris [email protected]

970-259-6801 x301Director of Policy and Research

Ecos Consulting

New Battery Charger Measurements Ongoing…

Li-Ion power tool charger NiCd power tool chargers

Cordless hygiene products

Power Conversion Durring a Cordless Tool Battery Charge Cycle

0

1

2

3

4

5

6

7

0.0 0.4 0.8 1.3 1.7 2.1 2.5 2.9 3.3 3.8 4.2 4.6 5.0 5.4 5.8 6.3 6.7

Hours

Pow

er (W

atts

) AC Input Power

DC Power Entering Charger

DC Power Entering Battery

Power supply efficiency @ charge start = 40%

Power supply efficiency @ charge end = 58%

Power supply efficiency @ 2 Hr. = 51%

Big differences between charge and maintenance mode power use in fast chargers

Charge for 14.4V NiMH Power Tool Battery Charger

0

10

20

30

40

50

60

0 0.25 0.5 0.75 1

Time (hrs)

Pow

er (W

atts

)

Charge Mode~ 49 watts

Maintenance Mode~ 3 watts

Not all Lithium Ion Chargers Have Low Power Use in Battery Maintenance Mode

Charge for 10.8V Li-Ion Multipurpose Tool Battery Charger

0

2

4

6

8

10

12

0 0.5 1 1.5 2 2.5 3 3.5

Time (hours)

Pow

er (A

C w

atts

) Charge Mode~ 9.5 watts

Maintenance Mode~ 4 watts

In some products, power use high in all “low power” modes, even with

extra features switched off

Charge for 12V Power Tool Battery Charger/Portable Stereo

0

5

10

15

20

25

30

35

40

45

0 1 2 3 4 5

Time (hours)

Pow

er (A

C w

atts

) Charge Mode~ 36 watts

Maintenance Mode~ 17 watts

In some consumer battery chargers, little difference between charge and maintenance

Charge Curve for 9.7 Volt Cordless Drill NiCd Battery Charger

0

1

2

3

4

5

6

0 30 60 90 120 150 180 210 240 270 300 330

Minutes

Pow

er (A

C W

atts

)

Charge Mode4 - 5.5 watts

Battery Maintenance Mode4 watts

Maintenance

Maintenance

Maintenance

Battery discharge at different rates can yield more/less energy

10.8V Li-Ion Multipurpose Tool Battery Discharge

0

2

4

6

8

10

12

14

0 1 2 3 4 5

Time (hours)

Pow

er (A

C w

atts

)

1C discharge0.2C discharge

12.9 Wh

13.2 Wh

On a percentage basis, nominal battery capacity can be higher than, lower than, or

similar to measured battery capacity

Normalized Comparison of Battery Capacity

0%

50%

100%

150%

Power Drill 15-min AA BatteryCharger

Cordless MultipurposeTool

Cordless Drill Ladies' Wet/DryRechargeable Shaver

Men's RechargeableBeard Trimmer

Per

cent

of R

ated

Ene

rgy

Cap

acity

RatedMeasured at slow dischargeMeasured at fast discharge

NiMH Li-Ion NiCd

Charge Rates Nicad NiMh Li-Ion Lead Acid

Slow 0.2C 0.2C 0.2C ?

Fast 1.0C 0.5C 1.0C ?

Voltage Indicating End of Charge 0.9 volts 0.9 volts 3.0 volts 1.75 volts

Differences by Chemistry

Charge and Maintenance Power Levels Are Closer to Each Other in Slow Chargers; Much Different in Fast Chargers

Power Consumption in Battery Chargers

0

10

20

30

40

50

60

70

80

Power Drill 15-min AA BatteryCharger

Cordless Tool Power Tool Charger Charger/Portable Stereo

Ave

rage

Pow

er (A

C w

atts

)

Charge Maintenance Standby

User behavior determines which mode dominates annual energy use

Annual Energy Use of 15-Minute AA Battery Charger

0.8

0.8

0.3

0.3

0.0

13.2

0 2 4 6 8 10 12 14

1 charge/week

1 charge/weekcontinuous standby

Annual Energy Use (kWh)

Standby ModeMaintenance ModeCharge Mode