Electrical Upgrades

2024 PMU

Old Point Comfort Yacht Club

Electricity Explained

• E=IR P=VA
• Voltage (V) is the potential to do work
• The higher the voltage, the less current it takes to do the same amount of work
• Less current allows the use of smaller diameter wire
• 1000 watt motor has internal resistance of 0.144 ohms. 12V requires 84 amps. If wiring has an ohm of resistance, 50 amps is now dissipated by cable leaving only 352 watts of energy for the motor.
• More on wire size later

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Simple Tests

• Set voltmeter to DC. Check ground to positive. Should have a voltage, usually 12 v system on older boats.
• Keep black lead on ground and move red lead along circuit path to determine where there is a problem. Red wire tested with red lead.
• Current not usually needed to be measured
• Set voltage to AC. Insert black lead into the long slot, red lead into the other slot, should read 110 v. Move black lead to round part of plug, should read 110 v. Move red lead to long slot, should read 0.
• If measuring wiring, red lead to black wire and black lead to white wire. Round part of plug is green.

Why Upgrade

• Old boats end up with spaghetti in an unorganized pile
• When gremlins come to visit
• Equipment “breaks” on a regular basis
• Electronics drop offline when using heavy loads
• Adding electronics or other equipment when no spare capacity exists
• Adding inverters and/or solar
• Upgrading battery banks

Why Upgrade

• Wine Down was a Beneteau sailboat.
• Factory wiring was done with terminal blocks and there were no ferrules on wires
• Many intermittent issues with lights and other circuits
• Wheel-Pilot had multiple control head and motor failures due to power and ground leads too large for terminal blocks
• Major upgrades to electronics
• Navy Lady
• Add inverter
• Battery failure so prepare for lithium and solar
• Upgrades
• Electronics dropouts
• Significant voltage drops and engine instrument degradation

Battery Systems

• Batteries can be connected in series or parallel.
• Series increases voltage, parallel voltage stays the same.
• Series power is the same, parallel power increases
• Battery banks should ideally be balanced before installation and connected to keep them balanced

Battery Chemistry

• Group Size and weight
• Lead Acid Batteries
• Lead Acid Golf Cart Batteries
• AGM
• Lithium
• Build your own
• Already configured
• Packaged server batteries
• Automotive/Marine electric engine upgrades

Batteries for Navy Lady

• On Wine Down I was able to cruise with just two Group 27 batteries
• Navy Lady requires a large capacity start battery (1000 CCA or more)
• Running home type fridge and freezer requires significant power and inverter (don’t run the microwave for boiling water!)
• Wanted to be able to do solar and lithium but costs and time made the decision to use AGM.
• Size of battery box only allows 4 Group 31
• Newer AGM batteries allows for 1 start battery and 3 left for the house bank.

Lithium Batteries

• Costs are dropping significantly as capacity increases
• Not as cost effective building your own anymore
• There is now a 425 amp hour lithium battery
• Since lithium batteries use a battery management system, it is recommended to have at least two batteries for continuity of service
• Jim Beaudry built his own including significant solar installation

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Battery capacity and charge rates

• 3600 w inverter provides 30 amps of AC power but requires 300 amps of DC @ 12 V
• AGM battery charge current 10 – 15 amps per battery but that can take up to 10 hours to recharge
• 60 amps per battery for an equivalent Lithium and now 4 hours or less
• For the 425 AH battery > 120 amps, but double if you need the redundancy
• Battery cables need to be able to handle the current

Wire and fuse size selection

• Wire sized for maximum current
• Wire is also sized for allowable voltage loss for the required current
• Fuses or other current protection devices are designed to protect the wire
• Sub-branch circuits are fused to protect equipment

Wire Resistance per 1000 feet

Bow Thruster – 400 amps. 12’ 2/0, 25’ 4/0, 25’ 4/0. .000936*12+.00004*50=1.4 Ignore connections and switches. 0.4 volts from short 2/0 cable alone

Bilge Pump 15 A. 12’ 2/0, 20’ 6, 20’ 14 4 volt loss, if neg 14, 6 volts

Now assume windlass, bilge and other high amp loads at the same time: 6 AWG at 100 amps 1.5 volt additional loss and it affects all loads. 2 AWG goes to 0.6 v and 2/0 goes to 0.3 volts.

ABYC Cheat Sheet – Thanks Jim DiSomma

-200MV – Cathodic protection

1 Ohm – resistance on a conductor – More not good. ABYC only

1 Ohm Max resistance on fuel fill grounding

1” – Battery can’t move

2.5” between throttle and steering wheel

3% - drop for critical systems, i.e. navigation equipment, lights, electronics, bilge pumps and blowers.

10% non critical (courtesy lights)

4 – Number of conductors on a single post, biggest on bottom. Stack nicely

5 mA – GFCI, protects people, trips 5mA

ABYC Cheat Sheet – Thanks Jim DiSomma

4 gauge – Lighting protection

5 mA – GFCI, protects people, trips 5mA, weather decks, machinery spaces, heads, galley

7’ run an ungrounded conductor from power source before requiring overcurrent protection

8 gauge – Commonly used for bonding (green wire not be confused with AC ground)

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10’ between shore power inlet and electrical panel, over 10 feet need some type of ELCI or RCD

16 gauge – smallest wire you should find on a boat

18’ – between support of wires/conductors

30 mA – NEW an ELCI will trip. ELCI protects boat and equipment from stray voltage leak

ABYC Cheat Sheet – Thanks Jim DiSomma

36” – battery cable can run without support, excludes outboards

40” – run from a source (other than a battery) when sheathed, before you need overcurrent protection

72” – run a sheathed, in conduit, before needing overcurrent protection

80 – 100% -steering system voltage operating parameters

1200 Mv – anything greater than this can cause hydrogen bubbling of paint

What your system should look like

Layout

• As an engineer I over analyze but I spent months drawing out my installation
• The current design looks very different than initial design
• Is there a great distance between batteries and electrical panel placement
• Cable bend radius
• Connector placement for ease of routing

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Designing a system

• Using references and specifications, decide on major components
• Batteries
• Current protection
• Switches
• Inverters
• Monitoring
• Large current items – bow thruster, windlass, motors
• Do you want breakers of fuses
• Do you want easy access to multiple switches/applications

Factory Systems

• Majority use breaker panels and inline fuses for electronic protection
• Often a battery selection switch 1, 2 Both
• Usually have a Main DC breaker
• Yachts may use relays and electronic switches

My System

• I like the use of circuits broken into buses – Maybe because of my avionics background
• Battery Bus – bilge pumps, fire detection, monitoring
• DC Bus – lights, water pump, head pump,
• ACC Bus – engine instruments and electronics needed when engine is off
• On Bus – electronics and other equipment need when engine is running
• Don’t see the need to turn multiple things on/off
• Like the ease of use of a single switch to select the state of the boat
• Use a master switch and engine switch has an ACC and ON position
• Battery bus is powered full time unless battery switch is off

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Wiring

• Large capacity battery switches already installed for battery selection and paralleling batteries
• 4/0 wiring directly from switches/bus bar to/from engine and to/from bow thruster No bow thruster battery is installed. Might be cost prohibitive at todays copper prices
• 2/0 from individual batteries to post and 4/0 after combined.
• Double 2/0 to/from inverter
• 2/0 from alternator
• 2/0 to/from battery to bus fuse block, master switch and negative bus

Wiring

• An additional 4/0 to a negative bus for the aft end of the boat
• Victron 1000 amp shunt installed and connected to Cerbo GX
• 2 AWG to/from master switch to upper helm fuse block
• 2 AWG from master switch to DC fuse block and through relay to ON
• 4 AWG wire to ignition switch
• 6 AWG from ignition switch to ON and ACC fuse blocks
• 8 AWG for relay in upper helm for ON bus
• Existing wiring for now on all branch unless inadequate

Fuse Blocks

• 3 - 12 circuit Blue Sea ATO fuse blocks
• Each capable of 120 amps total
• 30 amps per individual circuit
• One each for battery, DC, and On bus
• 2 – Dual 6 circuit Blue Sea ATO fuse blocks with integral negative bus
• 120 amps total, 30 amps per circuit
• Each split into an ACC and ON bus
• Allows good grounding for all engine instruments instead of daisy chain grounding currently used