Terry Sparks Commander USN Retired
Dec 30, 2015
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