Lecture #3 Lecture #3 Basic ElectricityBasic Electricity

Why learn electronics?Why learn electronics? Ability to understand Ability to understand

information sensor information sensor is providingis providing

Be able to read a Be able to read a wring diagramwring diagram

Basic understanding Basic understanding of what some of what some components are components are doing in the circuitdoing in the circuit

Troubleshooting!!!Troubleshooting!!!

BasicsBasics• Electricity is the flow of electronsElectricity is the flow of electrons

• Many similarities with the flow of waterMany similarities with the flow of water

• Water flows Water flows

because of a because of a

pressure pressure

differencedifference

• Bigger pipes Bigger pipes

allow more allow more

flowflow

• A complete circuit is A complete circuit is required for current to required for current to flowflow

• Also required:Also required:– A source of “pressure” A source of “pressure”

(voltage)(voltage)

• Optional:Optional:– SwitchSwitch– Something to do workSomething to do work

TermsTerms

• VoltageVoltage– Electrical potential differenceElectrical potential difference– Electrical “pressure”Electrical “pressure”– UnitsUnits

•Volts (v)Volts (v)

• CurrentCurrent– Flow of electron charge (phenomenon)Flow of electron charge (phenomenon)– Rate of Flow of Electron charge (quantity)Rate of Flow of Electron charge (quantity)– Units Units

•Ampere (A)Ampere (A)

• Resistance: the resistance to flowResistance: the resistance to flow

• Friction in the pipeFriction in the pipe

• Units Units – Ω – OhmΩ – Ohm

• SymbolSymbol

• -WW--WW-

Terms (cont)Terms (cont)

Simple EquationsSimple Equations

• Ohm's LawOhm's LawE=IRE=IR

•E– Voltage (volts)E– Voltage (volts)

• I – Current (amps)I – Current (amps)

•R – Resistance (ohm)R – Resistance (ohm)

• PowerPowerP=IEP=IE

•WattsWatts

Components: ResistorsComponents: Resistors

• Electronic component that provides Electronic component that provides resistance to the flow of electronsresistance to the flow of electrons

• Come in variety of sizes and ability to Come in variety of sizes and ability to handle powerhandle power

ResistorsResistors

• In SeriesIn Series– Resistance values (Ohms) add up to give Resistance values (Ohms) add up to give

total resistancetotal resistance

– RR11+R+R22+R+R33...=R...=Rtotaltotal

• In ParallelIn Parallel– Each have same potential differenceEach have same potential difference

– 1/R1/R11+1/R+1/R22...=1/R...=1/Rtotaltotal

Using resistorsUsing resistors

• Voltage dividerVoltage divider

• Use Ohm’s law to calculate:Use Ohm’s law to calculate:– CurrentCurrent– Voltage between A and BVoltage between A and B– Voltage Between B and CVoltage Between B and C

• Assume:Assume:– RR11 is 1000 is 1000 ΩΩ and R and R22 is 1000 is 1000 ΩΩ

– RR11 is 2000 is 2000 ΩΩ and R and R22 is 3000 is 3000 ΩΩ

A

C

B

Special resistorsSpecial resistors

• Variable resistor: 2 terminalsVariable resistor: 2 terminals– ExamplesExamples

•Audio controlAudio control

• JoysitckJoysitck

•RheostatRheostat

• Potentiometer: 3 terminalsPotentiometer: 3 terminals– Voltage dividerVoltage divider

DiodesDiodes

• One-way valvesOne-way valves– Allow current to flow in one directionAllow current to flow in one direction

• There is a drop in voltage across a diodeThere is a drop in voltage across a diode– Drop is ~ 0.7VDrop is ~ 0.7V

• Two main typesTwo main types– Single diodeSingle diode

•Up to 100mAUp to 100mA

– Rectifier diodeRectifier diode•Large CurrentsLarge Currents

• SymbolSymbol

DiodesDiodes

• Used to separate battery packsUsed to separate battery packs

• Also used to “idiot proof” Also used to “idiot proof” connectionsconnections

• Called “diode isolation”Called “diode isolation”

• More later….More later….

DiodesDiodes

• Light Emitting Diodes (LED)Light Emitting Diodes (LED)– Color is determined by the Color is determined by the

semiconductor material usedsemiconductor material used– Still need to be connected in the Still need to be connected in the

correct directioncorrect direction•Current flow long to shortCurrent flow long to short

– Easy to blow upEasy to blow up•Limit voltage/currentLimit voltage/current

CapacitorsCapacitors

• Passive Electronic componentPassive Electronic component

• A pair of conductor separated by a dielectricA pair of conductor separated by a dielectric

• When a voltage is applied a charge builds upWhen a voltage is applied a charge builds up– Acts like a little batteryActs like a little battery

• Why when you shut off certain things the light stays lit Why when you shut off certain things the light stays lit for a little even with no powerfor a little even with no power

• Eg. Computer power supplyEg. Computer power supply

• Units: Units: F - Farad F - Farad

• Symbol: -||-Symbol: -||-

• Be very careful of very big ones……Be very careful of very big ones……

CapacitorsCapacitors

• In SeriesIn Series– The energy stored is equal to that of the The energy stored is equal to that of the

other capacitors in the seriesother capacitors in the series•1/C1+1/C2...=1/Ceq1/C1+1/C2...=1/Ceq

• In ParallelIn Parallel– Add up the capacitanceAdd up the capacitance

•C1+C2+C3...=CtotalC1+C2+C3...=Ctotal

• Opposite that of ResistorsOpposite that of Resistors

• Using Using capacicapacitors:tors:

• AbsorAbsorb b voltagvoltage e spikesspikes

MultimetersMultimeters

• Tool used to test electronics (Main tool)Tool used to test electronics (Main tool)– VoltageVoltage

•Straight forward touch ends to terminalsStraight forward touch ends to terminals

– CurrentCurrent•Need to put in sequenceNeed to put in sequence

•Be sure you won’t exceed rating!!!!Be sure you won’t exceed rating!!!!

– Validity of a cableValidity of a cable•““Ohm out”Ohm out”

•Used to Identify the same Used to Identify the same

wire in a cablewire in a cable

DC vs AC DC vs AC

• Alternating Current (AC)Alternating Current (AC)– Polarity changes over timePolarity changes over time

• Basic form is a sine waveBasic form is a sine wave– Other wave forms existOther wave forms exist

– Better for long distance transmission of Better for long distance transmission of powerpower• High voltages – Low currentHigh voltages – Low current

• PPll=I=I22RR– If current is doubled then 4x greater lossIf current is doubled then 4x greater loss

– Easily generated by a generator/alternatorEasily generated by a generator/alternator• Polarity changes as magnet spinsPolarity changes as magnet spins

– Can be “stepped up” and down using a Can be “stepped up” and down using a transformer (more later)transformer (more later)

– Not used in Oceanographic instrumentation*Not used in Oceanographic instrumentation*• AC to DC converter almost always neededAC to DC converter almost always needed

*Not often, anyway

DC vs ACDC vs AC

• Direct Current (DC)Direct Current (DC)– Unidirectional flow of electric chargeUnidirectional flow of electric charge– SourcesSources

•BatteriesBatteries

•Solar PanelsSolar Panels

– Used in low voltage applicationsUsed in low voltage applications– More complicated then ACMore complicated then AC– AC can be converted to DC AC can be converted to DC

• using a rectifierusing a rectifier

http://electronicsprojects.mediadir.in/category/hobby-circuits/page/84/

DC vs ACDC vs AC

http://electronicsprojects.mediadir.in/category/hobby-circuits/page/84/

What is Electro-Magnetism?What is Electro-Magnetism?• Until 1821, only one kind of Until 1821, only one kind of

magnetism was known, the magnetism was known, the one produced by iron magnets. one produced by iron magnets.

• Then a Danish scientist, Hans Then a Danish scientist, Hans Christian Oersted discovered Christian Oersted discovered electromagnetism:electromagnetism:

– He noticed that the flow of He noticed that the flow of electrical current in a wire electrical current in a wire caused a nearby compass caused a nearby compass needle to move. needle to move.

– The new phenomenon was The new phenomenon was studied in France by Andre-studied in France by Andre-Marie Ampere, Marie Ampere,

– He concluded that the nature He concluded that the nature of magnetism was quite of magnetism was quite different from what everyone different from what everyone had believed. had believed.

All magnetism is related to All magnetism is related to electricityelectricity

• There thus exists There thus exists two kinds of forcestwo kinds of forces associated with electricity:associated with electricity:

– electricelectric

– magnetic. magnetic.

• In 1864 In 1864 James Clerk MaxwellJames Clerk Maxwell demonstrated a subtle connection demonstrated a subtle connection between the two types of forcebetween the two types of force

– The connection involves the velocity of The connection involves the velocity of light. light.

– From this connection sprang the idea that From this connection sprang the idea that light was an electric phenomenon, light was an electric phenomenon,

– This led to the discovery of radio waves, This led to the discovery of radio waves, the theory of relativity and a great deal of the theory of relativity and a great deal of present-day physics.present-day physics.

• A Changing A Changing magnetic field will magnetic field will “induce” a “induce” a voltage.voltage.

• Or, you can Or, you can rotate a wire rotate a wire inside a inside a magnetic field.magnetic field.

• Generators Generators and alternatorsand alternators

ElectromagnetismElectromagnetism• If you use one wire to If you use one wire to

generate a changing field generate a changing field (AC), it will induce voltage (AC), it will induce voltage in a nearby coilin a nearby coil

• You can isolate circuits this way

– Works through plastic, glass, aluminum, water

• But AC will also induce noise into adjacent wires

– Shielding helps

– Twisting wires helps

• The voltage induced is determined by the ratio of the number of winds on the coil

– So you can step up or step down

– Only with AC

SwitchesSwitches

• Used to turn things on and off (duh!)Used to turn things on and off (duh!)

• But come in lots of flavors:But come in lots of flavors:– MomentaryMomentary– ToggleToggle– RotaryRotary– polespoles

•SPST: single pole single throwSPST: single pole single throw

•SPDT: Single pole, double throughSPDT: Single pole, double through

•DPST: double pole, single throwDPST: double pole, single throw

•DPDT: double pole, double throwDPDT: double pole, double throw

•Etc.Etc.

RelaysRelays

• Electrically operated Electrically operated switchesswitches

• Generally use an Generally use an electromagnet to close electromagnet to close a switcha switch

• End result: use a small End result: use a small switch (limited current switch (limited current capability) to operate a capability) to operate a larger switch (with larger switch (with larger current larger current capacity)capacity)

Relay applicationsRelay applications

• CarsCars– HornHorn– LightsLights– StarterStarter

• Ocean:Ocean:– Sensor powerSensor power– Burn wiresBurn wires– Controller powerController power– motorsmotors

TransistorsTransistors

• ““relays” made of relays” made of semiconductorssemiconductors

• Used to control circuitsUsed to control circuits

• Used to amplify signalsUsed to amplify signals

• Replaced vacuum tubesReplaced vacuum tubes

• Gazillions of them in a Gazillions of them in a computercomputer– We’ll learn later how they are We’ll learn later how they are

used in digital logicused in digital logic

How transistors workHow transistors work(Don’t sweat the details)(Don’t sweat the details)

• Like two diodes back to backLike two diodes back to back– No current can flowNo current can flow

• But if you apply voltage to the But if you apply voltage to the middle layer, it ionizes (semi-middle layer, it ionizes (semi-conducts), allowing current throughconducts), allowing current through

• More voltage = more flowMore voltage = more flow

• Variable “switch”Variable “switch”– more like a valvemore like a valve

Typical transistor circuitTypical transistor circuit

• Apply voltage to VApply voltage to Vin in to to

make current flowmake current flow

• Note resistorNote resistor– Combines with transistor to Combines with transistor to

create a voltage dividercreate a voltage divider

– Result is using VResult is using Vinin to control to control VVoutout

– But VBut Vinin may have VERY may have VERY small voltage fluctuations small voltage fluctuations while Vwhile Voutout has large has large fluctuationsfluctuations

Analogue SignalAnalogue Signal

• Continuous signalContinuous signal– As that current changes the signal changesAs that current changes the signal changes– Usually 0-5v, but can varyUsually 0-5v, but can vary

• Important when using analogue that your datalogger can Important when using analogue that your datalogger can handle the voltage produced by the sensorhandle the voltage produced by the sensor

• AdvantagesAdvantages– Infinite signal resolutionInfinite signal resolution– Can be processed by analog componentsCan be processed by analog components

• DisadvantagesDisadvantages– NoisyNoisy

• Shielded cable can help diminish the noiseShielded cable can help diminish the noise

– Subject to loss in cables and connectorsSubject to loss in cables and connectors

Digital SignalDigital Signal

• Non-continuous signalNon-continuous signal

• Two amplitude levels Two amplitude levels

called nodescalled nodes– Digital logicDigital logic

•0 or 10 or 1

•True or false, yes or no, on or offTrue or false, yes or no, on or off

• Fixed number of digits or bitsFixed number of digits or bits

• Sent as binary and needs a program Sent as binary and needs a program to convert to “readable” valuesto convert to “readable” values

Analog to Digital ConversionAnalog to Digital Conversion

• All analogue signals are converted to digital All analogue signals are converted to digital for processingfor processing– Resolution of the data depends on the A/D Resolution of the data depends on the A/D

converter usedconverter used• Signal is placed into bitsSignal is placed into bits

– Stored in binaryStored in binary

• Example – 12bit A/D converterExample – 12bit A/D converter– Range 0-5vRange 0-5v– A/D resolution 12bits: 212 =4096 quantization A/D resolution 12bits: 212 =4096 quantization

levelslevels– Analog voltage resolution is: 5V/4096Analog voltage resolution is: 5V/4096

• Meaning each “level” is equal to ~1.22mV/“level”Meaning each “level” is equal to ~1.22mV/“level”

Communications types Communications types • AnalogueAnalogue

– Direct signalDirect signal

• DigitalDigital– SerialSerial

• RS 232RS 232– Most commonMost common– 15m max length15m max length– 20kbs max speed20kbs max speed

• RS 485RS 485– 1200 max length1200 max length– 100kbs @ 1200m100kbs @ 1200m– 35 Mbs @ 15m35 Mbs @ 15m

– Parallel: almost obsoleteParallel: almost obsolete– EthernetEthernet

• Large data transferLarge data transfer

Instruments require PowerInstruments require Power

No Power No dataNo Power No data– All sensors require power to operate, All sensors require power to operate,

some more than otherssome more than others How long with the sensor last?How long with the sensor last? How many sensors can I run off one How many sensors can I run off one

datalogger?datalogger? Which batteries should I go with?Which batteries should I go with?

– Rechargeable or primary (one time use)Rechargeable or primary (one time use) How many batteries do I need?How many batteries do I need?

Powering Marine InstrumentationPowering Marine Instrumentation

• Two main optionsTwo main options– BatteriesBatteries– Sea cableSea cable

• Power from ship or shorePower from ship or shore• Usually allows data to be “Live Feed” Usually allows data to be “Live Feed”

as wellas well

Sea CablesSea Cables

• DC Power from shipDC Power from ship– Usually 12-15 voltsUsually 12-15 volts– Power limited due to:Power limited due to:– Slip ringsSlip rings– DistanceDistance– Surface power supplySurface power supply

– Usually not limited by voltageUsually not limited by voltage• Depends on what is at the other end of the cable for Depends on what is at the other end of the cable for

interfacing the sensorinterfacing the sensor

• Majority of ship deployment setups use Sea CablesMajority of ship deployment setups use Sea Cables

Sea CablesSea Cables• What if your sensor What if your sensor

requires more power or requires more power or higher voltage higher voltage – Use a battery Use a battery – but data may still be able to but data may still be able to

be sent up the sea cablebe sent up the sea cable

• What if the ship only has What if the ship only has one sea cable?one sea cable?– (Usually hooked to the CTD)(Usually hooked to the CTD)– Bring your own sea cableBring your own sea cable– Use a batteryUse a battery

What is a battery?What is a battery?

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Does size matter?Does size matter?

• Yes and NoYes and No– YesYes

•The larger the battery the more capacity it hasThe larger the battery the more capacity it has– That is, more amp hoursThat is, more amp hours

– NONO•Batteries of all sizes can supply the same voltageBatteries of all sizes can supply the same voltage

• Which size?Which size?– What is your voltage (do you need to make What is your voltage (do you need to make

a string?)?a string?)?– Which will give you the most power per $$ Which will give you the most power per $$

or power per cmor power per cm33??

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Battery TerminologyBattery Terminology

• Primary battery:Primary battery: not rechargeable not rechargeable• ChargeCharge: The conversion of electrical : The conversion of electrical

into chemical energy.into chemical energy.• CycleCycle: One complete discharge and : One complete discharge and

charge or vice-versa.charge or vice-versa.• CapacityCapacity: The battery’s ability to : The battery’s ability to

provide a sustained current for a given provide a sustained current for a given amount of time. Units: Ampere-hours amount of time. Units: Ampere-hours (Ah).(Ah).

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• PowerPower: The rate of doing work. Power : The rate of doing work. Power (Watts) = E(Volts) x I(Amps).(Watts) = E(Volts) x I(Amps).• Self DischargeSelf Discharge: The process by which a : The process by which a

battery discharges without an external battery discharges without an external load due to internal chemical reactions.load due to internal chemical reactions.• Shelf life: Shelf life: the amount of time a battery the amount of time a battery

can remain in storage before its capacity can remain in storage before its capacity has reduced to a specified level.has reduced to a specified level.

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Types of batteriesTypes of batteries

• Lead AcidLead Acid– Wet Cell (2 Wet Cell (2

types):types):• Serviceable Serviceable

(flooded)(flooded)• Maintenance Maintenance

free (sealed)free (sealed)– Gel CellGel Cell– Absorbed Glass Absorbed Glass

Mat (AGM)Mat (AGM)– Valve-regulated Valve-regulated

(VRLA) for UPS, (VRLA) for UPS, emergency emergency lights, and lights, and security systemssecurity systems

Types of batteriesTypes of batteries• Carbon-zinc: These are the plain, old-fashioned Carbon-zinc: These are the plain, old-fashioned

batteries: 1.5Vbatteries: 1.5V– power of 950mAh (AA)power of 950mAh (AA)– sloping discharge curve (voltage drops as capacity is sloping discharge curve (voltage drops as capacity is

used.used.– Operating range down to 20Operating range down to 20⁰ ⁰ FF

•They perform very poorly at low temperatureThey perform very poorly at low temperature

•at -5at -5⁰ ⁰ F their service life is decreased by 75% and output drops F their service life is decreased by 75% and output drops quickly as the temperature drops below room temperaturequickly as the temperature drops below room temperature

– shelf life is 1/3 to 1/10th of other types - about 3.5 shelf life is 1/3 to 1/10th of other types - about 3.5 years.. years..

– On the plus side, they're cheap. On the plus side, they're cheap.

• AlkalineAlkaline

• Lithium-ionLithium-ion

• Nickel Metal HydrideNickel Metal Hydride

• Nickel CadmiumNickel Cadmium

Types of batteriesTypes of batteries

• Alkaline (Duracell, Energizer etc): 1.5VAlkaline (Duracell, Energizer etc): 1.5V– Capacity: about 2850mAhCapacity: about 2850mAh

•Depends on discharge rateDepends on discharge rate

•More in lithium section More in lithium section

– sloping discharge curve. sloping discharge curve. – Operating range is down to 0Operating range is down to 0⁰⁰FF

•at -5at -5⁰ ⁰ F their service life is decreased by 60% F their service life is decreased by 60% and output drops quickly as the temperature and output drops quickly as the temperature drops below room temperature.drops below room temperature.

– shelf life is 10+ years. shelf life is 10+ years. – Although they're more expensive, they're Although they're more expensive, they're

comparable to carbon-zinc in terms of cost comparable to carbon-zinc in terms of cost per hour of use.per hour of use.

Types of batteriesTypes of batteries

• Lithium: 3V (but newer chemistries are 1.5)Lithium: 3V (but newer chemistries are 1.5)– About the same capacity as alkaline, ~2900mAh About the same capacity as alkaline, ~2900mAh – flat discharge curve: voltage stays high until flat discharge curve: voltage stays high until

nearly all capacity is gone and then drops. nearly all capacity is gone and then drops. – Operating range down to -40Operating range down to -40⁰⁰F; F;

•at -5at -5⁰⁰F their service life only is decreased by 20% and F their service life only is decreased by 20% and output decreases slowly as the temperature dropsoutput decreases slowly as the temperature drops

– Shelf life is 10+ years. Shelf life is 10+ years. – They're also much more expensiveThey're also much more expensive– Also can be dangerous; may explode if Also can be dangerous; may explode if

“shorted”“shorted”

Caveats Caveats

• Useable capacity depends on discharge Useable capacity depends on discharge raterate– Especially in alkaline batteriesEspecially in alkaline batteries

Consider temperature effectsConsider temperature effects

• Alkalines lose a lot Alkalines lose a lot of capacity at deep of capacity at deep sea temperaturessea temperatures

Data.energizer.com

DischargeDischargeCurvesCurves

• Digital Digital electronics electronics shut down shut down when a when a minimum minimum voltage is voltage is reached.reached.

Data.energizer.com

Rechargeable VS One-time useRechargeable VS One-time use

• RechargeableRechargeable– ProPro

•Multiple usesMultiple uses– Saves moneySaves money

•Saves having to open the instrumentSaves having to open the instrument

– ConsCons•Usually have less amp hours / cellUsually have less amp hours / cell

•Sometimes can cost a lotSometimes can cost a lot– But should be made up for in usesBut should be made up for in uses

•Often have higher self-discharge ratesOften have higher self-discharge rates

Types of rechargeable batteriesTypes of rechargeable batteries

• Nickel Cadmium (NiCd) (1.2V)Nickel Cadmium (NiCd) (1.2V)– Previous standard, now obsoletePrevious standard, now obsolete– Serious memory issuesSerious memory issues

• Nickel Metal Hydride (NiMH) (1.2V)Nickel Metal Hydride (NiMH) (1.2V)– Now the standardNow the standard– Less memory but still require special careLess memory but still require special care

• Lithium ion (3.6V)Lithium ion (3.6V)– No memory; low self discharge rateNo memory; low self discharge rate– Extreme energy densityExtreme energy density– Require very specific charging circuitsRequire very specific charging circuits

Wikipedia.comWikipedia.com

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Battery Charging; general rulesBattery Charging; general rules

• Recharge batteries immediately after they are Recharge batteries immediately after they are discharged. discharged. • Li ion should be stored at ½ chargeLi ion should be stored at ½ charge

• Do not discharge them more than 80% of their Do not discharge them more than 80% of their normal capacity.normal capacity.• NiMH can be very hard to bring backNiMH can be very hard to bring back

• Recharge them at the rate recommended by Recharge them at the rate recommended by manufacturermanufacturer• Control by varying voltage and monitoring AmpsControl by varying voltage and monitoring Amps

• Have the positive and negative terminals clearly Have the positive and negative terminals clearly marked.marked.

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Battery Life and PerformanceBattery Life and Performance

• Batteries sit too long between charges.Batteries sit too long between charges.• Batteries are stored without some type Batteries are stored without some type

of energy input like a trickle charge.of energy input like a trickle charge.• ““Deep cycling” a battery designed to Deep cycling” a battery designed to

start an engine reduces its life.start an engine reduces its life.• Undercharging a battery reduces Undercharging a battery reduces

performance.performance.• Heat > 100Heat > 100oo Fahrenheit increases Fahrenheit increases

internal discharge.internal discharge.

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• Cold weather reduces the internal Cold weather reduces the internal chemical activity and less energy is chemical activity and less energy is produced.produced.

• Low electrolyte level in the cells.Low electrolyte level in the cells.

• Incorrect charging levels from Incorrect charging levels from inexpensive battery chargers.inexpensive battery chargers.

Myths About BatteriesMyths About Batteries

• A battery will discharge if it is in contact A battery will discharge if it is in contact with concretewith concrete. Modern battery cases are . Modern battery cases are made of polypropylene or hard rubber.made of polypropylene or hard rubber.

• A battery will not lose its charge while A battery will not lose its charge while sitting in storage. sitting in storage. Batteries have a Batteries have a normal self-discharge of 1% to 25% a normal self-discharge of 1% to 25% a month. month.

• A battery will not explodeA battery will not explode. Hydrogen . Hydrogen and oxygen gasses are produced during and oxygen gasses are produced during recharging.recharging.

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• This battery This battery was part of an was part of an emergency emergency generatorgenerator

• It exploded It exploded while being while being charged during charged during a routine test.a routine test.

6161http://www.rayvaughan.com/battery_safety.htm

Providing batteries to your instrument: Providing batteries to your instrument: buy or build?buy or build?

• Most oceanographic sensor companies Most oceanographic sensor companies will sell you the battery packs needed for will sell you the battery packs needed for their sensor.their sensor.– They will also replace that battery pack at a They will also replace that battery pack at a

some cost when the pack diessome cost when the pack dies

• May be cheaper to build your own packMay be cheaper to build your own pack– Only time it is not cheaper is when it Only time it is not cheaper is when it

becomes too specializedbecomes too specialized•Configuration is complicatedConfiguration is complicated

– i.e. glider batteries or ADCPi.e. glider batteries or ADCP

– Possibly turn it into a rechargeablePossibly turn it into a rechargeable• If amp hours requirements will allowIf amp hours requirements will allow

Oceanographic BatteryOceanographic Battery

• Depth Depth problemsproblems– Need to oil Need to oil

compensate compensate for depthfor depth

• Temperature at Temperature at depth can depth can affect affect performanceperformance

How many batteries do I need?How many batteries do I need?

• Total voltage for sensor(s)Total voltage for sensor(s)– SeriesSeries

• VVtotaltotal = V1+V2+V3... = V1+V2+V3...– 12v car battery is nothing but 6 – 2v 12v car battery is nothing but 6 – 2v

cellscells

How many batteries do I need?How many batteries do I need?

• How long do you want it to last!?How long do you want it to last!?– Batteries in ParallelBatteries in Parallel

•Only put batteries of the same voltage in Only put batteries of the same voltage in parallel!! parallel!!

•Add up Amp hoursAdd up Amp hours

How many batteries do I need?How many batteries do I need?

• Use a combination on series and Use a combination on series and ParallelParallel

• How big is your pressure housingHow big is your pressure housing– i.e. How much space do you have?i.e. How much space do you have?

Oceanographic Battery SafetyOceanographic Battery Safety• Test all batteries for voltage before plugging them into Test all batteries for voltage before plugging them into

you sensoryou sensor– Especially ones you have made!!Especially ones you have made!!– Wrong voltage or polarity could mean dead sensors!Wrong voltage or polarity could mean dead sensors!

• Salt Water and Batteries do not mixSalt Water and Batteries do not mix– Corrodes batteries and then they leakCorrodes batteries and then they leak

• Lithium batteries and waterLithium batteries and water– Releases gasesReleases gases– Dissolves quickly Dissolves quickly

• If happens in your pressure housing you have a bomb!!!If happens in your pressure housing you have a bomb!!!

• Be careful when opening any pressure housing with Be careful when opening any pressure housing with batteries after any deploymentbatteries after any deployment– You don't know the state of the batteriesYou don't know the state of the batteries

• Open any pressure housing when recharging batteriesOpen any pressure housing when recharging batteries– Gases released during charging Gases released during charging