marine electrical systems on auxiliary sailboats
DESCRIPTION
Marine Electrical Systems on Auxiliary Sailboats. Topics To Discuss. Major AC and DC electrical systems typically found on small to medium size auxiliary sailboats. Tools and supplies needed to install or repair those systems. Troubleshooting techniques for common problems. Safety. - PowerPoint PPT PresentationTRANSCRIPT
Marine Electrical Systemson
Auxiliary Sailboats
Topics To Discuss
• Major AC and DC electrical systems typically found on small to medium size auxiliary sailboats.
• Tools and supplies needed to install or repair those systems.
• Troubleshooting techniques for common problems.
• Safety
Nomenclature
• AC – Alternating Current (120 volts AC)
• DC – Direct Current (12 volts DC)
• V – voltage - volts
• I – current – amperage or amps
• R – resistance - ohms
AC Systems
AC Systems & Components
• Shore Power Connection
• AC Electrical Panel
• Cabin Outlets
• Battery Charger
• Inverter / Chargers
• Hot Water Heater
• Galvanic Isolator
Shore Power Connection
Shore Power Cables
AC Panel
• Sometimes separate but often integrated with the DC Panel.
• AC Main circuit breaker - 30 amp.
• Individual load circuit breakers - 15 amp.
• Reverse Polarity Indicator – warning when neutral line is not at ground potential.
AC Only Panels
Integrated AC / DC Electrical Panel
Reverse AC Polarity Problem• AC circuit breakers are single pole which means
they only disconnect hot wire.• If polarity is reversed then neutral is hot and not
switched.• If neutral is tied to the metal case of an
appliance then there is a shock hazard.• Reverse polarity indicator will not function if
ground is missing.• Always best to disconnect shore power cord
when working on AC systems.
Reverse Polarity Indicator Circuit
AC Outlets Same as those in your house – 120 volts 15 amps
Battery Charger
• Typically provides 10 to 50 amps of charging current depending on manufacture and model.
• Normally has charge state indicators but often mounted where they cannot be seen.
• Better models provide 3 charge stages; bulk, absorption, and float.
Battery Chargers
20 amps max 50 amps max
Inverter / Charger
• At the dock charges the both house and starting batteries.
• Away from the dock provides 120 Volts AC from the house battery.
• Usually include automatic transfer switch for AC loads.
• Available battery charging current and AC power output depends on size.
Inverter / Chargers
Hot Water Heater
• Typically 120 Volts, 1500 watts, 12.5 amps
• Can be round or rectangular, horizontal, or vertical.
• Often include a heat exchanger that uses engine coolant to heat water when under power.
Hot Water Heaters
Galvanic Isolator
Bonding (Grounding) System
Galvanic Isolator• Not really an AC system but is connected in the
AC line.• Isolator prevents low voltage DC path in shore
power ground wire.• Engine, metal through hulls, prop and shaft are
often all electrically connected or bonded together and connected to boat ground.
• Zincs attached to shaft and bonding system are sacrificial anodes to prevent corrosion of bronze prop and through hulls
• Common shore power ground will provide conduction path to other boats and dock with potential corrosion problem.
Galvanic Isolator
DC Systems
DC Systems
• Main Battery Switch
• DC Panel
• Batteries
• Engine Alternator
• Engine Starting Motor
• Typical Loads
Main Battery Switch
• All major connections to batteries go through this switch.
• Exceptions are battery chargers and auto bilge pumps
• Allows selection of Battery 1, Battery 2, Both or Off (None)
Main Battery Switch
DC Panel
• Sometime separate but often integrated with the AC Panel.
• Usually has a MAIN DC circuit breaker.
• Circuit breakers for individual loads.
• DC Voltmeters and Ammeters.
DC Only Panels
AC / DC Electrical Panel
Typical DC Loads
• Starter Motor• Lights• VHF Radio• Instruments (Depth, Speed, Wind)• GPS – Chart Plotter• Auto Pilot• Stereo• Water Pressure Pump
Batteries
Batteries
• Lead, Lead Dioxide, Sulfuric Acid• Normally 12 Volts DC, sometimes two 6 volt
batteries connected in series for 12 volts.• Sometimes grouped in parallel for higher current. • 12 volt battery constructed of 6 individual cells that
are two volts each.• Types: Starting, Deep Cycle, and
Marine/Hybrid/Dual Purpose• Construction: Wet Cell, Gell Cell, AGM (Absorbed
Glass Mat)
Series / Parallel Configurations
Two 6 Volt Batteries in Series
Two 12 volt batteries in parallel
Starting Battery
• Designed for high current - short duration use.• Large number of thin plates for maximum
surface area.• May last for thousands of 2% to 5% of capacity
discharges.• However, if deep cycled the thin plates will
quickly be consumed and fall to the bottom of the cells.
• Will generally fail after 30 to 150 deep cycles of 20% to 80% depending on design.
Deep Cycle
• Designed to be discharged down to as much as 80% of capacity.
• Thicker plates than a starting battery.
• Fewer thicker plates mean less surface area and therefore less current capability.
• However, Deep Cycle batteries can still be used for starting if large enough.
Marine / Hybrid / Dual Purpose
• Designed as a compromise between Starting and Deep Cycle.
• Some Marine batteries are actually Deep Cycle.
• In some hybrid designs plates are composed of lead sponge but coarser than true Starting batteries.
• Often hard to tell what it is without opening the case which is not an option.
Wet / Flooded Cell Batteries
• Most common and usually least expensive.• Can be designed for starting, deep cycle or
hybrid use.• Liquid electrolyte so mounting is important, must
be mounted horizontally.• May vent hydrogen and oxygen generated by
electrolysis at end of charge or if overcharged.• Cases need to be vented.• Electrolyte level must be monitored and topped
up periodically.
Gel Cell Batteries
• Normally designed for deep cycle applications.• A thickening agent immobilizes the electrolyte.• Valve-regulated design means batteries are sealed
so mounting is not critical.• However, if overcharge hydrogen and oxygen will
escape through valves.• Since batteries are sealed and cannot be refilled
with electrolyte charging is more critical.• Gel cells use slightly lower charging voltages than
wet cells and thus the set-points for charging equipment have to be adjusted
AGM, (Absorbed Glass Mat) Batteries
• Normally designed for deep cycle applications.• Liquid electrolyte.• Uses a fiberglass like separator to hold the electrolyte in place
by capillary action. • Physical bond between the separator fibers, the lead plates,
and the container make AGMs spill-proof and the most vibration and impact resistant lead-acid batteries.
• Valve-regulated, sealed, so electrolyte cannot be replaced.• Small amounts of hydrogen and oxygen will be trapped and
recombine. Large amounts will vent.• AGMs use almost the same voltage set-points as flooded
cells and thus can be used as drop-in replacements for flooded cells.
Flooded Electrolyte Batteries
AGM Batteries
Gel Cell Batteries
Lead Acid Battery State of ChargeAfter 3 hour rest
State of Charge 12 Volt battery Volts per Cell
100% 12.7 2.12
90% 12.5 2.08
80% 12.42 2.07
70% 12.32 2.05
60% 12.2 2.03
50% 12.06 2.01
40% 11.9 1.98
30% 11.75 1.96
20% 11.58 1.93
10% 11.31 1.89
0 10.5 1.75
Why Batteries Fail
• Leaving batteries in a discharged state which leads to Lead Sulfation.
• Deep discharging a Starting Battery which damages the plates.
• Excessive vibration and shock damaging the plates.
• Long term sulfation due to normal battery use.
Lead Sulfation• When batteries are discharged amorphous lead
sulfate is formed on the plates. • If recharged soon the lead sulfate is easily
converted back to lead, lead dioxide, and sulfuric acid.
• However, if the battery is left in a discharged state too long the lead sulfate will convert to a crystalline form and will not convert back to lead, etc., during normal charging.
• This process will eventually coat the plates with non-conductive crystalline lead sulfate and kill the battery.
Lead Acid Battery Charge Stages
• Bulk – Charge current is set to maximum safe rate batteries will accept until voltage rises to near (80-90%) full charge level. Voltages at this stage typically range from 10.5 volts to 15 volts.
• Absorption - Voltage remains constant and current gradually tapers off as internal resistance increases during charging. It is during this stage that the charger puts out maximum voltage. Voltages at this stage are typically around 14.2 to 15.5 volts.
• Float - After batteries reach full charge, charging voltage is reduced to a lower level (typically 12.8 to 13.2) to reduce gassing and prolong battery life.
Lead acid Battery Charge Curves
Battery Maintenance
• Keep correct electrolyte level using only distilled water. (Wet cells only)
• Keep terminals clean.
• Keep batteries dry, especially the top.
• Make sure charging levels are correct.
• Keep batteries fully charged.
Battery Safety Issues• Batteries contain sulfuric acid which can cause eye
and skin burns and damage clothes.• A charging battery may contain significant amounts
of hydrogen which could explode if ignited.• Batteries can source hundreds of amps of current
and can melt jewelry around your finger or arm.Therefore:• DO - wear safety glasses and protective clothing.• DON’T - wear rings, bracelets or expensive clothes.• DON’T – allow sparks or flames near batteries,
especially when they are charging.
Engine Electrical Systems
Engine Alternator• Basically the same as the one in your car.• Provides current to charge batteries and operate
equipment, 40 to 100 amps.• Usually has an internal voltage regulator but
high end ones have an external regulator.• High current load requires significant force to
turn alternator so keeping belt tight is important.• Output voltage varies depending on model and
voltage regulator specifications. Range is 13.0 Vdc to 14.6 Vdc which presents an issue for proper battery charging.
Marine Engine Alternators
Yanmar 2/3 QM
Yanmar 2/3 QM
Starting Motor & Solenoid
• Solenoid – relay that switches high current to starter motor, typically draws around 10 amps.
• Starting motor may require 100 amps or more.
• Starting motor circuit requires very large gauge wires to minimize voltage drop and therefore power loss.
Starting Motor & Solenoid
Yanmar Starter Motors
Installation
Repair
Troubleshooting
Installation & Repair
• Tools
• Supplies
• Ohms Law / DC Power
• Wire Size Relative to Load
• Wire Terminals
• Wire Insulation Stripping
Tools
• Book: Boatowner’s Mechanical & Electrical Manual by Nigel Calder
• AC/DC Multimeter
• Assorted flat blade and phillips screw drivers
• Assorted pliers and cutters
• Adjustable, open and box end wrenches
• Wire stripper and terminal crimper
Repair and Installation Materials
• Wire
• Wire Terminals
• Electrical tape
• Shrink tubing
• Tie raps
Ohms Law
I = V/R, V=I*R, R = V/I
What is the voltage drop in a wire with a resistance of 1 ohm carrying 10 amps of current?
V = I*R = 1*10 = 10 volts
DC Power
P = V*I, V=P/I, I = P/V
What is the current for a 12 watt light bulb connected to a 12 volt battery?
I = P/V = 12/12 = 1 Amp
Wire Gauge for 3% Voltage Drop (Critical Loads)
Current (Amps)
5 10 15 20 25 30 40 50 60 70 80 90 100
Length (Feet) Wire Gauge (AWG)
10' 18 14 12 12 10 10 8 8 6 6 6 4 4
15' 16 12 10 10 8 8 6 6 4 4 4 2 2
20' 14 12 10 8 8 6 6 4 4 4 2 2 2
25' 14 10 8 8 6 6 4 4 2 2 2 1 1
30' 12 10 8 6 6 4 4 2 2 2 1 1/0 1/0
40' 12 8 6 6 4 4 2 2 1 1/0 1/0 2/0 2/0
50' 10 8 6 4 4 2 2 1 1/0 1/0 2/0 3/0 3/0
60' 10 6 6 4 2 2 1 1/0 2/0 1/0 3/0 3/0 4/0
Wire Gauge for 10% Voltage Drop (Non-Critical Loads)
Current (Amps)
5 10 15 20 25 30 40 50 60 70 80 90 100
Length (Feet) Wire Gauge (AWG)
10' 18 18 18 16 16 14 14 12 10 8 8 6 6
15' 18 18 16 16 14 14 12 12 10 8 8 6 6
20' 18 16 16 14 12 12 10 10 8 8 8 6 6
25' 18 16 14 12 12 10 10 8 8 8 6 6 6
30' 18 16 14 12 10 10 8 8 8 6 6 6 4
40' 16 14 12 10 10 8 8 6 6 6 4 4 4
50' 16 12 10 10 8 8 6 6 4 4 4 4 2
60' 16 12 10 8 8 8 6 4 4 4 2 2 2
Wire Diameter versus Gauge
AWG Diameter (inches) AWG Diameter (inches)
OOOO 0.46 8 0.1285
OOO 0.4096 9 0.1144
OO 0.3648 10 0.1019
0 0.3249 11 0.0907
1 0.2893 12 0.0808
2 0.2576 13 0.072
3 0.2294 14 0.0641
4 0.2043 15 0.0571
5 0.1819 16 0.0508
6 0.162 17 0.0453
7 0.1443 18 0.0403
Wire & Wire Terminals
• Should always use stranded wire not solid. Marine environment exposes wire to shock and vibration which could fracture solid wire.
• Tinned stranded provides much better corrosion protection than bare copper.
• Use crimped on terminal to make connection.• Use proper tool to crimp on terminal.• Use pull test after crimping to insure proper
crimp.• If you can pull the terminal off by hand, the crimp
is poor.
Marine Grade Wire – Tinned Stranded Copper
Tinned stranded copper wire.
Corroded copper wire.
Clean copper wire
Wire Terminals
Wire Insulation Stripping
• Do it right, use a wire stripping tool.
• If possible avoid using side cutters or a knife which will nick the wire and cause strands to break off.
• Strip off only enough insulation to crimp on the terminal.
Wire Strippers
Wire Terminal Examples
Excellent crimp on small terminal. Notice the slight extension of wire beyond the crimp.
Heavy gauge wire terminals. Sealing heat shrink tubing was used. Notice the small amount of sealing compound to the left of the tubing. This should be a water tight connection with maximum corrosion resistance.
VHF Radio Antenna Coax Cable
Coax cable has center conductor, spacer, shield, and outside sheath or cover.
Spacing between conductor is critical.
Should not be bent to small radius as this will change spacing of conductor and reduce signal.
For marine applications both center conductor and shield should be tinned copper.
Best connectors require special tools for installation but there are tool-less versions.
Shrink Tubing, Tie Wraps, Electrical Tape
Trouble Shooting & Installation
• Basics
• Light doesn’t work.
• VHF Radio doesn’t work.
• Batteries don’t charge.
• Engine won’t turn over.
• Bilge Pump Installation
Trouble Shooting Basics
One of four possible problems• Intermittent connection• Open connection (Blown fuse or open
breaker)• Reverse connection• Short (Usually includes a blown fuse or open
breaker)
Light Doesn’t Work
1. Verify battery is on, main breaker is on and load breaker is on.
2. If there is a fuse instead of a breaker remove and check for continuity.
3. Remove light bulb, do visual check or test bulb for resistance, should be less than 100 ohms.
4. Test voltage at socket pins, be careful not to short test leads together or to metal case.
5. Open up panel and check for voltage on both sides of circuit breaker.
6. If everything checks OK then problem is in wiring.
VHF Radio Doesn’t Work
1. Verify battery is on, main breaker is on and load breaker is on.
2. If there is a fuse instead of a breaker remove and check for continuity.
3. Make sure unit is turned on, volume is up and squelch is off. Select weather channel.
4. Make sure antenna coax connector is attached.5. Remove power connector and test for 12 volts.6. Remove antenna coax connector and check for short
between center conductor and shield.7. If you have static but no signal connect an external
antenna. This can be just a piece of wire stuck into the center of the connector.
Batteries Don’t Charge
• Measure voltage across batteries with all loads off, engine off, and battery charger off. Should be approximately 12.7 volts for a fully charged battery. (See battery charge state chart.)
• If possible start engine and check battery voltage, should be greater and increasing with maximum of approximately 13.8 volts. If not then alternator problem.
• Turn on battery charger and check battery voltage. Should be greater and increasing with maximum of approximately 14.4 volts. If not then battery charger problem.
• If battery voltage increases with either engine running or battery charger on, then batteries will charge. Batteries may not hold a charge if they are old or damaged.
Bilge Pump Installation
• Rule – Mate RM750A 750 GPH• Current at 13.6 Vdc is 3.1 amps• Want as much output as possible so this is
a critical application.• From wire size table 16 gauge is a good
choice.• If automatic operation is desired wire
directly to battery or battery switch with in-line fuse.
Safety
Causes of Fires Started On Board *AC and DC wiring/appliance 55%
– DC shorts/wiring - 30%– DC engine voltage regulator - 12%– AC appliance/heater - 4%– Shore power - 4%– AC wiring/panel - 2%– DC battery charger - 2%– AC power surge - 1%
* (Source – Boat US Blog – Data not verified)
Post Class Recommendations
• Get a copy of Nigel Calder’s book and read it cover to cover.
• Sign up for a boat team to get hands on experience.