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Chapter 3Chapter 3

Direct CurrentPower

Direct CurrentPower

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OverviewOverview

• Batteries• Safety Precautions • Marine Storage Battery• Charging Systems• Battery Utilization

• Batteries• Safety Precautions • Marine Storage Battery• Charging Systems• Battery Utilization

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BatteriesBatteries

• Cells and Battery• Battery Chemistry

Primary Cells Secondary Cells

• Series and Parallel Connections

• Cells and Battery• Battery Chemistry

Primary Cells Secondary Cells

• Series and Parallel Connections

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Cells and BatteriesCells and Batteries

• Cells generates DC by chemical reaction Two dissimilar electrodes (conductors) Immersed in electrolyte (current carrying

solution) Voltage function of electrode material

• Difference on the Galvanic Scale• Covered in Chapter 5

• Battery Group of cells connected together Classes – Primary and Secondary

• Cells generates DC by chemical reaction Two dissimilar electrodes (conductors) Immersed in electrolyte (current carrying

solution) Voltage function of electrode material

• Difference on the Galvanic Scale• Covered in Chapter 5

• Battery Group of cells connected together Classes – Primary and Secondary

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Primary CellsPrimary Cells

• Primary cells can not be recharged Chemical process is not reversible aka “Dry Cell”

• Common chemistries Zinc-carbon Alkaline (zinc and manganese oxide)

• Use Flashlights Portable radios

• Nominal voltage 1.5 VDC

• Primary cells can not be recharged Chemical process is not reversible aka “Dry Cell”

• Common chemistries Zinc-carbon Alkaline (zinc and manganese oxide)

• Use Flashlights Portable radios

• Nominal voltage 1.5 VDC

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Secondary CellsSecondary Cells

• Secondary Cells can be recharged Reversible chemical reaction aka “rechargable”

• Common chemistries Lead-acid (2.1 VDC) Nickel-cadmium (1.2 VDC) Nickel-metal hydride (1.2 VDC)

• Use Cars and Boats

• Secondary Cells can be recharged Reversible chemical reaction aka “rechargable”

• Common chemistries Lead-acid (2.1 VDC) Nickel-cadmium (1.2 VDC) Nickel-metal hydride (1.2 VDC)

• Use Cars and Boats

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Series and Parallel Connections

Series and Parallel Connections

6 V @ 100 A

6 V @ 100 A

+ +

--

-

12 V @ 100 A

Series

12 V @ 50 A

12 V @ 50 A

+ +

- -

12 V @ 100 A

Parallel

12 V @ 50 A

+

-

12 V @ 100 A

+

-

12 V @ 50 A

24 V @ 50 A

Common

Dual Voltage

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Safety PrecautionsSafety Precautions

• Lead-Acid batteries May produce explosive gases Contain acid Battery acid & seawater produce Chlorine

Gas

• Charge batteries in well-ventilated area Keep sparks, flames and cigarettes away

• Wear eye, face and hand protection Baking Soda is effective neutralizing

solution

• Lead-Acid batteries May produce explosive gases Contain acid Battery acid & seawater produce Chlorine

Gas

• Charge batteries in well-ventilated area Keep sparks, flames and cigarettes away

• Wear eye, face and hand protection Baking Soda is effective neutralizing

solution

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Warning MessageWarning Message

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Marine Storage BatteriesMarine Storage Batteries

• Types• Technologies• Sizes• Marine Battery Ratings• Selection, Installation and

Maintenance

• Types• Technologies• Sizes• Marine Battery Ratings• Selection, Installation and

Maintenance

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TypesTypes

• Starting battery Large amount of current for very short time Not fuse protected

• Deep-Cycle battery Power for many hours Can be discharged to 50% capacity Protected by large (200 to 400A) fuse

• Dual-Purpose battery Large plates (like starting) Thick plates (like deep-cycle)

• Starting battery Large amount of current for very short time Not fuse protected

• Deep-Cycle battery Power for many hours Can be discharged to 50% capacity Protected by large (200 to 400A) fuse

• Dual-Purpose battery Large plates (like starting) Thick plates (like deep-cycle)

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TechnologiesTechnologies

• Flooded Sometimes called “flooded” or “free-

vented”

• Gelled Electrolyte (Gel) Also called Valve-Regulated Lead Acid

(VRLA)

• Absorbed Glass Mat (AGM) Also called Valve-Regulated Lead Acid

(VRLA)

• Flooded Sometimes called “flooded” or “free-

vented”

• Gelled Electrolyte (Gel) Also called Valve-Regulated Lead Acid

(VRLA)

• Absorbed Glass Mat (AGM) Also called Valve-Regulated Lead Acid

(VRLA)

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FloodedFlooded

• Traditional marine battery Electrolyte is water-diluted sulfuric acid Electrodes are lead Free vented – charging gases escape

• Advantages Low initial cost Good deep-cycle performance

• Disadvantages Spillable electrolyte High self-discharge rate

• Traditional marine battery Electrolyte is water-diluted sulfuric acid Electrodes are lead Free vented – charging gases escape

• Advantages Low initial cost Good deep-cycle performance

• Disadvantages Spillable electrolyte High self-discharge rate

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Gelled Electrolyte (Gel)Gelled Electrolyte (Gel)

• Gelled Electrolyte Electrolyte is a gel

• Mixture of sulfuric acid, fumed silica & phosphoric acid

Pressure-relief vents (charging gases can’t escape)

• Advantages Spillproof / leakproof (can be used in any

orientation) Lowest cost per cycle Low self discharge rate

• Disadvantages High initial cost Can be damaged, if charged at wet cell rate

• Gelled Electrolyte Electrolyte is a gel

• Mixture of sulfuric acid, fumed silica & phosphoric acid

Pressure-relief vents (charging gases can’t escape)

• Advantages Spillproof / leakproof (can be used in any

orientation) Lowest cost per cycle Low self discharge rate

• Disadvantages High initial cost Can be damaged, if charged at wet cell rate

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Deep-Cycles Gel BatteryDeep-Cycles Gel Battery

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Absorbed Glass Mat (AGM)

Absorbed Glass Mat (AGM)

• Designed for military aircraft Use matted glass fibers between plates

• Advantages Spillproof / leakproof (can be used in any

orientation) Most shock and vibration resistant

• Disadvantages Capable of fewer discharge cycles

• Designed for military aircraft Use matted glass fibers between plates

• Advantages Spillproof / leakproof (can be used in any

orientation) Most shock and vibration resistant

• Disadvantages Capable of fewer discharge cycles

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Advantages / DisadvantagesAdvantages /

Disadvantages

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SizesSizes

Group Size Amp Hours Typical Size, in. Weight, lbs.(l x w x h) (typical Gel)

U1 30 - 40 8 x 5 x 7 23

24 70 - 85 11 x 7 x 10 54

27 85 - 105 13 x 7 x 10 63

31 95 - 125 13 x 7 x 10 72

4D 180 - 215 21 x 9 x 10 130

8D 225 - 255 21 x 11 x 10 161

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Battery RatingsBattery Ratings

• Ampere-hour (Ah) – Storage capacity• Open Circuit Voltage (V) – Battery at rest• Starting batteries

Cold Cranking Amps (CCA) – 30 sec at 0 F Marine Cranking Amps (MCA) – 30 sec at 32 F Reserve Capacity (RC) – minutes of 25 A at 80 F

• Deep-cycle batteries Rated Capacity – Amp-hours for 20 hr at 80 F Deep Cycle Capacity

• Ability to provide small amounts of current over time• Ability to withstand long, deep discharges

• Ampere-hour (Ah) – Storage capacity• Open Circuit Voltage (V) – Battery at rest• Starting batteries

Cold Cranking Amps (CCA) – 30 sec at 0 F Marine Cranking Amps (MCA) – 30 sec at 32 F Reserve Capacity (RC) – minutes of 25 A at 80 F

• Deep-cycle batteries Rated Capacity – Amp-hours for 20 hr at 80 F Deep Cycle Capacity

• Ability to provide small amounts of current over time• Ability to withstand long, deep discharges

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Battery Ratings by Battery Type

Battery Ratings by Battery Type

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Selection, Installation and Service

Selection, Installation and Service

• Selection DC Power Requirements Typical 24-hour load

• Installation

• Maintenance (Service) Water Cleaning Terminals Winter Lay-up

• Selection DC Power Requirements Typical 24-hour load

• Installation

• Maintenance (Service) Water Cleaning Terminals Winter Lay-up

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SelectionSelection• Starting Battery replacement

Same Group Size and MCA Initial Cost or Life Cycle Cost?

• Flooded – Less expensive to buy

• House (Deep-cycle) Battery replacement Consider increased capability

• Double battery life if depth of discharge only 25%

Initial Cost or Life Cycle Cost?• Gel - Capable or more discharge cycles

• Ratios (Battery size to largest expected load) Flooded – 4 to 1 Gel and AGM – 3 to 1

• Starting Battery replacement Same Group Size and MCA Initial Cost or Life Cycle Cost?

• Flooded – Less expensive to buy

• House (Deep-cycle) Battery replacement Consider increased capability

• Double battery life if depth of discharge only 25%

Initial Cost or Life Cycle Cost?• Gel - Capable or more discharge cycles

• Ratios (Battery size to largest expected load) Flooded – 4 to 1 Gel and AGM – 3 to 1

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DC Power RequirementsDC Power Requirements

• What source of DC power? Powerboat normally powered off an

alternator Sailboats normally powered off House Battery If anchored – Generator or House Battery?

• How often between battery charging?

• Limit depth of discharge to 50% For minimal charging time - Limit depth to

35% Battery life cut in half, if discharge to 75%

• Following table gives typical DC power demands

• What source of DC power? Powerboat normally powered off an

alternator Sailboats normally powered off House Battery If anchored – Generator or House Battery?

• How often between battery charging?

• Limit depth of discharge to 50% For minimal charging time - Limit depth to

35% Battery life cut in half, if discharge to 75%

• Following table gives typical DC power demands

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Typical 24-hour LoadTypical 24-hour Load

12-volt Demand Load Estimated Estimated(house battery) (in Amperes) Hours Used Amp-hours

Running Lights 3.0 2 6.0Anchor Light 0.6 10 6.0Cabin Lights 3.6 6 21.6

Bilge Pump 8.0 0.5 4.0Fresh Water Pump 7.0 1 7.0Refrigerator 5.7 8 45.6

VHF Radio 1.0 8 8.0GPS Receiver 0.8 8 6.4Radar 3.0 8 24.0

TOTALS 32.7 128.6

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InstallationInstallation

• Flooded batteries require Vented battery compartment Easy access to add water

• All batteries Should be in acid-resistant box Secured with insulated cover

Starting battery located near engine Don’t mix battery age in a battery bank Don’t mix battery chemistry in battery

bank

• Flooded batteries require Vented battery compartment Easy access to add water

• All batteries Should be in acid-resistant box Secured with insulated cover

Starting battery located near engine Don’t mix battery age in a battery bank Don’t mix battery chemistry in battery

bank

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Maintenance (Service)Maintenance (Service)

• Flooded-cell require distilled water Rapid loss in single cell indicates bad battery Rapid loss in all cells indicates

high charging voltage

• Never force open or add water to Gel or AGM

• Clean and tighten terminals twice a year Use special battery tools (illustrated on next

slide) Can remove corrosion with Baking Soda solution

• Don’t get solution into battery fill ports Apply battery “grease” to terminals

• Flooded-cell require distilled water Rapid loss in single cell indicates bad battery Rapid loss in all cells indicates

high charging voltage

• Never force open or add water to Gel or AGM

• Clean and tighten terminals twice a year Use special battery tools (illustrated on next

slide) Can remove corrosion with Baking Soda solution

• Don’t get solution into battery fill ports Apply battery “grease” to terminals

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Battery ToolsBattery Tools

• Dirty or loose battery terminals can materially reduce the energy available from a battery

• Use proper battery tools to prevent damage to battery

• Dirty or loose battery terminals can materially reduce the energy available from a battery

• Use proper battery tools to prevent damage to battery

Battery TerminalPuller

Battery TerminalCleaner

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Winter Lay-upWinter Lay-up

• Fully charge and service before winter lay-up Flooded batteries should be equalized

• Disconnect negative battery terminal cable

• Flooded deep-cycle should be charged every 50 days

• Gel and AGM should be charged every 6 months Also flooded starting

• Continuous trickle charge not recommended Unless have automatic cutoff

• Fully charge and service before winter lay-up Flooded batteries should be equalized

• Disconnect negative battery terminal cable

• Flooded deep-cycle should be charged every 50 days

• Gel and AGM should be charged every 6 months Also flooded starting

• Continuous trickle charge not recommended Unless have automatic cutoff

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Charging SystemsCharging Systems

• Basic Considerations• Degree of Charge• Alternators• AC Battery Chargers• Inverter/Charger• Other

• Basic Considerations• Degree of Charge• Alternators• AC Battery Chargers• Inverter/Charger• Other

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Basic ConsiderationsBasic Considerations

• Charging requires more charge (in amp-hours) than removed Flooded 115 to 120% VRLA 105 to 114%

• Phases Bulk at 20 to 40% of battery's capacity

• Continues until 75% full Acceptance charging rate is steadily

reduced• Continues until accepted current equals 2%

capacity Float current is only 0.1 to 0.2 Amps

• Maintenance, not charging

• Charging requires more charge (in amp-hours) than removed Flooded 115 to 120% VRLA 105 to 114%

• Phases Bulk at 20 to 40% of battery's capacity

• Continues until 75% full Acceptance charging rate is steadily

reduced• Continues until accepted current equals 2%

capacity Float current is only 0.1 to 0.2 Amps

• Maintenance, not charging

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Basic Considerations - 2Basic Considerations - 2

• Proper Charging Voltage depends on Temperature (table on slide 33 based on 80 F)

• Higher temperatures require lower voltage Battery Chemistry Table gives charging voltage by phase &

chemistry

• Flooded-cell Equalization Prevents “sulfation” Recommended every 20 to 50 cycles Over charge, after acceptance phase, to dissolve

lead sulfate crystals on battery’s plates High voltage may damage electronic equipment

• Proper Charging Voltage depends on Temperature (table on slide 33 based on 80 F)

• Higher temperatures require lower voltage Battery Chemistry Table gives charging voltage by phase &

chemistry

• Flooded-cell Equalization Prevents “sulfation” Recommended every 20 to 50 cycles Over charge, after acceptance phase, to dissolve

lead sulfate crystals on battery’s plates High voltage may damage electronic equipment

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Degree of ChargeDegree of Charge

• Flooded cell with hydrometer (most accurate)

• Gel and AGM with volt meter Can also use volt meter on flooded cell

• Next slide gives voltages for rested batteries Not charged or discharged for 24 hours Can also bleed off surface charge

• Use large light bulb for several minutes

• Flooded cell with hydrometer (most accurate)

• Gel and AGM with volt meter Can also use volt meter on flooded cell

• Next slide gives voltages for rested batteries Not charged or discharged for 24 hours Can also bleed off surface charge

• Use large light bulb for several minutes

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Lead-acid 12 volt Voltages

Lead-acid 12 volt Voltages

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AlternatorsAlternators

• Alternator converts AC to DC with diodes Don’t disconnect battery while alternator

running• “Zap-Stop” ® will protect diodes from damage

• Alternator sized at 25-40% of battery capacity

• Charging Diodes (Isolators) Permit charging of two batteries Have approx 0.6 to 0.7 voltage drop

• Increase alternator voltage for correct voltage at battery

Illustrated on next slide

• Alternator converts AC to DC with diodes Don’t disconnect battery while alternator

running• “Zap-Stop” ® will protect diodes from damage

• Alternator sized at 25-40% of battery capacity

• Charging Diodes (Isolators) Permit charging of two batteries Have approx 0.6 to 0.7 voltage drop

• Increase alternator voltage for correct voltage at battery

Illustrated on next slide

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Multiple Battery ChargingMultiple Battery Charging

+

-

+

--

EngineDrivenAlternator

BatteryIsolators

AC Charger(Two-outputs)

StartingBattery

HouseBattery

+

#1 +

#2 +-

-

Negative Common

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AC Battery ChargersAC Battery Chargers

• Basic charger (not recommended) Single output voltage Can’t do bulk, acceptance, and float

charging Can’t handle multiple chemistries

• Basic charger (not recommended) Single output voltage Can’t do bulk, acceptance, and float

charging Can’t handle multiple chemistries

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AC Battery Chargers - 2AC Battery Chargers - 2

• SCR multi-stage (recommended) Three phase charger (bulk, acceptance &

float)• Also will do equalization

Independent multiple outputs• Independent setting for Flooded, Gel and AGM• Independent as to phase

Best for Deep-Cycle

• SCR multi-stage (recommended) Three phase charger (bulk, acceptance &

float)• Also will do equalization

Independent multiple outputs• Independent setting for Flooded, Gel and AGM• Independent as to phase

Best for Deep-Cycle

2 outputs @ 10 Atemperate climate

3 outputs @ 40 Acold, warm or hot climates

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Inverters / ChargersInverters / Chargers

• Charger converts 120 VAC to DC

• Inverter converts 12 VDC to 120 VAC More on inverters in Chapter 4 on AC

• Advantages Lighter & cheaper than separate

systems

• Charger converts 120 VAC to DC

• Inverter converts 12 VDC to 120 VAC More on inverters in Chapter 4 on AC

• Advantages Lighter & cheaper than separate

systems2Kw inverter100A charger

3-stage multiple batteries

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OtherOther

• Solar Panels Low power output Requires controller or

regulator

• Wind Generator Ideal wind of 5 to 30

Kt Should be feathered or

stopped at over 35 Kt More power than solar

• Solar Panels Low power output Requires controller or

regulator

• Wind Generator Ideal wind of 5 to 30

Kt Should be feathered or

stopped at over 35 Kt More power than solar

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Battery UtilizationBattery Utilization

• Separate Starting and House• Battery Switches• Battery Monitor• Typical 12 volt System

• Separate Starting and House• Battery Switches• Battery Monitor• Typical 12 volt System

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Starting and House Batteries

Starting and House Batteries

• Two battery banks are recommended Starting – Large amount of current for short

period• Half of breakdowns are – engine won’t crank

House – Sustained power over long period of time• Discharge limited to 50%

• Old concept was “Off-1-Both-2” battery switch

• Two battery banks are recommended Starting – Large amount of current for short

period• Half of breakdowns are – engine won’t crank

House – Sustained power over long period of time• Discharge limited to 50%

• Old concept was “Off-1-Both-2” battery switch

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Battery SwitchesBattery Switches• Battery switches (current thinking)

Dedicated “Off-On” switch for each battery• Each battery charged separately• Prevents weaker battery discharging stronger one

• When need extra current to crank engine Close switch #3 to parallel both batteries

• Switch must be opened after engine is started

• Battery switches (current thinking) Dedicated “Off-On” switch for each battery

• Each battery charged separately• Prevents weaker battery discharging stronger one

• When need extra current to crank engine Close switch #3 to parallel both batteries

• Switch must be opened after engine is started

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Battery SwitchesBattery Switches

+

-

+

--

StartingBattery

HouseBattery

Negative Common

to Starter Solenoid

to PowerPanel

SW 1 SW 2

SW 3

F 1

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Battery MonitorsBattery Monitors• Battery Monitors keep track of

How much energy stored in battery How much energy has been removed How much energy is left in battery Time remaining at current discharge rate

• Sophisticated, computer based device• Voltmeter only provides current status

• Battery Monitors keep track of How much energy stored in battery How much energy has been removed How much energy is left in battery Time remaining at current discharge rate

• Sophisticated, computer based device• Voltmeter only provides current status

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Typical 12-volt SystemTypical 12-volt System• Next slide illustrates

Starting and House battery• Charged by alternator and charging diodes• Charged by two output, three stage battery

charger• Dedicated “Off-On” switches for each battery• Separate battery paralleling switch

Wires are color coded with size shown• Note bilge pump wiring

– Fuse in negative lead– Pump operated by either float switch

or panel switch Uses voltmeter to determine battery

charge

• Next slide illustrates Starting and House battery

• Charged by alternator and charging diodes• Charged by two output, three stage battery

charger• Dedicated “Off-On” switches for each battery• Separate battery paralleling switch

Wires are color coded with size shown• Note bilge pump wiring

– Fuse in negative lead– Pump operated by either float switch

or panel switch Uses voltmeter to determine battery

charge

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Typical 12 volt DiagramTypical 12 volt Diagram

Starter

SA

Alternator DieselEngine

#4 Black (or Yellow) #4

#10StartingBattery

HouseBattery

- -

#4 Red

#8

#8

BilgePump

FloatSwitch

3 StageBatteryCharger

BatteryIsolator(Diodes)

++#10

#12

#10

#10 Orange

#12 Brown#12 Brown

#12

V

#16

#16

SW1

SW2SW3

F1

F2

SW4

SW5

DCPowerPanel

CB1

+

-

#4

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SummarySummary

• Types of Marine Batteries Flooded-cell, Gel and AGM Starting, Deep-cycle and Dual-purpose

• Charge batteries in three phases Bulk, Acceptance and Float and if lead-acid, periodically equalize

• Keep binding posts & cables clamps clean

• Recommend battery charger / inverter

• Independent battery banks recommended

• Types of Marine Batteries Flooded-cell, Gel and AGM Starting, Deep-cycle and Dual-purpose

• Charge batteries in three phases Bulk, Acceptance and Float and if lead-acid, periodically equalize

• Keep binding posts & cables clamps clean

• Recommend battery charger / inverter

• Independent battery banks recommended