Terry SparksCommander USN Retired

AgendaWhy learn

Electricity?What is Electricity?What is DC?Overview of Boat DC

systemsThe Breaker Panel

Battery Types20 Minute BreakCharging SystemsBattery LoadingSafety

Why learn Electricity?Install equipment without cost for serviceInstalling equipment without fires

What size fuse do I need for equipment? Impact of new device on battery last? Battery size to sail to Catalina? Can I use an existing circuit breaker? Other questions can be answered with a little

knowledge.

What is ElectricityElectricity is:

Electrons being pushed through a conductive material such as wire or metal by a voltage source.

The limiting of electron flow is as a result of the resistance , the opposition to current flow.

The energy delivered or used by a device is called power.

What is ElectricityTypical Electrical Terms

Voltage in Volts (V, E)Current in Amps (A, I)Resistance in Ohms (Ω)Power in Watts (P)

What is DCDC stands for “Direct Current”Direct Current - current/electrons flows only

in one direction through a wire and an electrical device.

DC electric energy is supplied by your battery(s)

Devices used for charging batteries provide DC

PFlow -->>>>>

PSprayEnergy

Common point earth & atmosphere

Sprinkler isOpposition to flow

- +

Common point

Battery Heater/Resistance(Opposition to Flow)

Current -->>>>>

V

Heat is Energy/Power

- +

Common point

Battery Heater/Resistance(Opposition to Flow)

Current -->>>>>

V

Work DoneHeat / Energy/Power

Voltage in Volts = Current X Resistance = I X R

Current in Amps= Voltage/Resistance = V/R

Resistance in Ohms= Voltage/Current = V/I

Power in Watts= Voltage X Current = V X I

RIV

VIP

Example 1For a 25Watt bulb, what is the smallest

fuse we can install?

The 25 Watts is at the rated voltage of 12.6 Volts

So the current is P/V

25W/12.6V = 1.98 Amps (approximately 2 amp fuse)

VIP

Example 2When we turn the battery charger on the 2 A fuse

blows:With the charger on the voltage may go to 14.5V?

R=V/I so for a 25W component at 12.6VFrom before we found it I ~ 2A

RIV

RIVSo then the resistance is V/I or

12.6V/2A = 6.3 ohms

At the new Voltage of 14.5 Volts:

14.5V/6.3 ohms = 2.3A

Yep! The fuse would blow so it needs to be at least a 2.5A.

Your Turn!My new radio says it draws 2 A.

What is the Power?What is the Resistance?

RIV

VIP

- +

Battery

Boat Ground (Metal things)

Battery Select SwitchTo 2nd battery

DC Panel

VHFRadio

Navigation Lights

FMRadi

o

Fuse

BatteryCharger

ToBoatGround

Fuse

Or

Fuses Required?All devices should have a fuse or circuit

breaker on a 12 Volt power feed.Batteries and Battery chargers.

Devices connected directly to a battery A fused must also be installed within seven

inches of the battery connection.Charging can be through battery selector

switch.Still needs fuse on output of charger.

Charging to Battery directly requires 2 fuses.

The Breaker PanelFrequently two sections, DC and ACBreakers should be DC rated for current and

voltageThe current/wire size to be connected to the

breaker.A 20 amp breaker connected to at least #12 wireA 15 amp breaker connected to at least #14 wireLong runs of wire should have the next larger size Items connected to the wire should be less than

the breakerUse Marine stranded/tinned wire only

Battery Types Typical on BoatsThree classes of Batteries

Starting Batteries need lots of current available Recommend a 1000 MCA

battery Low cost units Also hook to thrusters and

anchor windless

Battery Types Typical on BoatsThree classes of Batteries (cont.)

House Batteries High Amp-hour rating Designed to draw smaller currents for long periods Needs to be capable of many charging cycles

Dual Purpose Good for Power Boaters

OK for House Current. OK for Starting Currents Not as good if planning a lot of anchoring.

Battery Types Typical on BoatsStarting batteries

Starting batteries start engines, not for deep discharge use. Many thin plates = maximum surface area, and maximum

current output. Repeated deep discharges will result in capacity loss and

ultimately in premature failure

A common Misconception: Starting batteries should be kept on float charge.

Float will encourage corrosion on the electrodes Result in premature failure. Starting batteries should be kept open-circuit but charged

at least once every two weeks to prevent sulfation.

Battery Types Typical on BoatsDeep cycle batteries

Specially designed deep-cycle cells are much less susceptible to degradation due to cycling

Required for applications where the batteries are regularly discharged Such as boat house batteries

Batteries have thicker plates Can deliver less peak current

Can withstand frequent Discharging and Charging.

Battery Types Typical on BoatsMarine Dual Purpose batteries

Are something of a compromise between the two types

Able to be discharged to a greater degree than starting batteries

But discharged less than a deep cycle batteries.

Battery Types Typical on BoatsLead Acid

Similar to the ones in most carsContains water and acidCan Leak if turned upside DownMore maintenance

Requires water to be added Terminals must be cleaned

Battery Types Typical on BoatsLead Acid

Voltage per cell when charged is 2.1VSo 6 cells in a 12 Volt Battery is 12.6 Volts (when

charged)Golf Cart Batteries have 3 Cells or 6.3 Volts

High Capacity batteries, great for House Batteries Most Charging cycles of any battery

Battery Voltages to think About Open-circuit at full charged: 12.6 V to 12.8 V Open-circuit at full discharged: 11.8 V to 12.0

V

Time to chargeBattery is at ½ power ~ 12.2V Open Circuit.

After full charge Terminal voltage will drop quickly to 13.2 V and

then slowly to 12.6 V.

Battery Voltages to think About Equalization charging for flooded lead acids

only15 V+ for no more than 2 hours once a month.

(I do 30-45 minutes every month) When all cells have equal specific gravity done.Battery temperature must be monitored.Make sure water level still good when complete

Gassing (Hydrogen Gas) threshold: 14.4 V At 15V make sure ventilation is good

Battery Types Typical on BoatsGel Cell

The acid is mixed with a silica fume creating a gel-like electrolyte.

Eliminates the electrolyte evaporation

Can be mounted in any positionRequires special setup on most

chargersThe least forgiving of the

battery types

Battery Types Typical on BoatsAGM (Absorbed Glass Mat)

Electrolyte is absorbed into a mat of fine glass fibers

Can be mounted in any positionSealed and glass mat protects plates

from shorting out with vibrationMost forgiving of all batteries for

both Charge and discharge.Clearly the best battery for boats,

but also the most expensive

Charging SystemsTypes

Alternator on the EngineShore Power or generator via a Battery

chargerSolar CellsWind GeneratorWater Wheel

Two engines one battery Two engines two banks

One engine two banks

One engine two or 3 banks(~0.7V drop on these devices)

TypeBulk /

Absorption Max Current Float* Equalize

Generic Flooded 14.4 30 13.5 15-17.5

Generic Gel 14.2 25 13.8 N/A

Generic AGM 14.3 30 13.45 N/A

* Precise (±0.05 V) float voltage is critical to longevity; too low sulfation is almost as bad as too high corrosion and electrolyte loss

Multi-Stage ChargingLongest Life on Batteries

Multi-Stage Charger Bulk Charge

A constant high current to initially charge the battery

Absorption Constant Voltage Charge to top off the battery

Float Charge Keeps enough voltage on the battery such that loads

requesting current end up coming from the charger instead of the battery. Keeps the battery fully charged.

Solar/Wind

Alternator

Multi-Stage ChargingEqualize to get longest Life - Lead Acid

BatteriesSelectable Equalizing Charge

Used as maintenance feature about once a month to knock off the material built up on the plates Result in an un-balanced charge per cell.

Will significantly extend the life of your Lead Acid Cells

15 V+ for no more than 2 hours once a month.

When all cells have equal specific gravity it is complete.

Hydrometer/Battery Tester

Alternator on the EngineFactory Alternators typically do not provide 3

or 4 charging stages Can reduce battery life

Alternators with an external regulator control typically do provide 3 or 4 charging stages.Will Provide Maximum Battery Life

Battery LoadingSailors worry about loading more than power

boatersWhen we are under sail they are draining the

battery. Conservation through the use of LEDS is like

adding another power source. DC lights draw about 2 Amps Similar LEDs 0.2A

2 Amp-hours vs. 0.2 amp-hours

(See Table next Slide)

Battery LoadingWhen you anchor over night, it is important

to have enough energy (Amp-hours) to:Provide cabin lightsAnchor light all night Start the engine the next morning.

An Isolated battery used only for starting is a smart choose

Watch a DVD, maybe “Captain Ron”

Better Battery switch designThe Battery one, Battery two, and both switches

are the worst way to control battery connection possible.Putting the switch in both when a battery is low

drains the good battery Will equalize both batteries to a lesser charge

Go through off to other batteryCharging may remain an issueHaving the switch in both provides for no backup.Not a good solution for a sailboats or trollersMay work ok for power boats

Still a poor solution

Better Battery switch designA better solution is 3 single switches.

One for House Battery – On/OffOne for Engine starting – On/Off One that cross connects the load to the other

load circuit. West Marine has a replacement module to

make it simple to convert

(See diagram next page)

• To energize the house supply engage S2• To start the Engine Engage S1•If Starting Battery is Low!

•Disengage S1 •Engage S3 with S2 Still engaged

•To use the Starting Battery on the House

•Disengage S2•Engage S3 with S1 Still engaged

• S1, S2, & S3 engaged equals the “Both” position on a traditional Battery Selector Switch. •All three should not be engaged as with the “Both” position, the charged battery will discharge to the un-charged battery.

Operation

** Banks of (2) 6 volt Golf cart batteries in series May provide the most charging cycles and hence longest life.

Ships DC Ground

To Starter

To Metering and Charging devices

To Metering and Charging devices

S1S2

S3

House

1-many12V Deep CycleBatteries**Number Based on AH required.

Starting BatteryWith High Cranking Current

Ties Loads

together not

BatteriesBoth/Bypass

BLUE SEA SYSTEMS Battery Switch/DC Circuit PanelWM Model #: 163233 Manuf. Part #: 8080

SafetyTips

Important to ensure boat does not burn!Smaller wires connected to the battery must be

fusedVoltages out of Chargers must be fusedWorm wires means to much currentWarn wires can result in shorts

SafetyTips

Cheap crimp connectors can result in poor and possibly arcing connections (Or Intermittent operation)

Shrink tube over connectors or use connectors that shrink

Use Crimping tool If you solder connectors, make sure the solder

does not wick up into the wire. Connectors without insulator on end Solder at connection only

Apply Solder Here

SafetyMore Tips

While 12V DC systems are to low a voltage to kill you, boats with 24V could. In rare cases when a persons is sweating and has a

low resistance enough current to kill you could be generated with as little as 24 volts

Be Safe, turn off the power before working on it While 12 Volts may not kill you, with all the current

available it could burn you wiring up if shorted,

Use Marine Grade Products Only