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 into : The conversion of electrical into

chemical energy.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 provide : The battery’s ability to provide

a sustained current for a given amount a sustained current for a given amount of time. Units: Ampere-hours (Ah).of time. Units: Ampere-hours (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 batteries: 1.5VCarbon-zinc: These are the plain, old-fashioned batteries: 1.5V

– power of 950mAh (AA)power of 950mAh (AA)– sloping discharge curve (voltage drops as capacity is used.sloping discharge curve (voltage drops as capacity is 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 F their service life is decreased by 75% and output drops quickly as the temperature drops below room drops quickly as the temperature drops below room temperaturetemperature

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

• 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.

2020http://www.rayvaughan.com/battery_safety.htm

Providing batteries to your Providing batteries to your instrument: 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 problemsDepth problems– Need to oil Need to oil

compensate compensate for depthfor depth

• Temperature at Temperature at depth can affect depth can 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 ParallelUse a combination on series and Parallel

• 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

ComputersComputers

Computer numeric systemsComputer numeric systems

• Different ways computer store dataDifferent ways computer store data– NumbersNumbers

•BinaryBinary•HexadecimalHexadecimal•OctalOctal•DecimalDecimal

– TextText•ASCIIASCII

BinaryBinary

• Base 2 systemBase 2 system– 0 and 10 and 1

• 0=00=0• 1=11=1• 10=210=2• 11=311=3• 100=4100=4• 101=5101=5• 110=6110=6• 111=7111=7• etcetc

OctalOctal

• Base 8 systemBase 8 system– Use 0-7 Use 0-7 – Binary numbers grouped into 3Binary numbers grouped into 3

•Decimal 112Decimal 112– Binary – 1110000 or 001 110 000Binary – 1110000 or 001 110 000– Octal = 160Octal = 160

(1*8(1*822)+(6*8)+(6*811)+(0*8) = 64 + 48 +0 = 112)+(0*8) = 64 + 48 +0 = 112

HexadecimalHexadecimal

• Base 16Base 16– 0-9 and A-F0-9 and A-F– A=10A=10– F=15F=15

Example – 8AC7 = 35527Example – 8AC7 = 35527

(8*16(8*1633)+(10*16)+(10*1622)+(12*16)+(12*1611)+(7*16)+(7*1600))

Data storageData storage

• Bit – binary digit Bit – binary digit – 0 or 10 or 1– So small usually worked with in groups of 8So small usually worked with in groups of 8

• Byte = 8 bitsByte = 8 bits– Numeric values 0-255Numeric values 0-255

• Kilobyte = 1024 bytesKilobyte = 1024 bytes

• Megabye =1024 KB or (1024*1024) Megabye =1024 KB or (1024*1024) bytesbytes

Flashback to last weekFlashback to last week

• A/D convertersA/D converters– 0-5v analog signal through a 12-bit A/D 0-5v analog signal through a 12-bit A/D

converter – What is the resolution of the converter – What is the resolution of the signal?signal?

– 16bit – resolution?16bit – resolution?

MemoriesMemories

• Computers, by definition, have memoriesComputers, by definition, have memories– hold the programhold the program

• a program is what makes a computer a computera program is what makes a computer a computer

– hold datahold data

• Requirements of memory:Requirements of memory:– enter dataenter data– save datasave data– retrieve dataretrieve data

• What is memory?What is memory?– recording of a series of binary numbers (that's all)recording of a series of binary numbers (that's all)– in the case of data, these are actually numbersin the case of data, these are actually numbers– in thee case of a program, these may be numbers or may be a in thee case of a program, these may be numbers or may be a

truth table showing the computer how to respond to a given truth table showing the computer how to respond to a given circumstance.circumstance.

Memory typesMemory types• Non-Volatile (mass storage device)Non-Volatile (mass storage device)

– - used for long-term storage- used for long-term storage– magnetic core = magnetized donuts which store bitsmagnetic core = magnetized donuts which store bits

• isn't used very much any moreisn't used very much any more• takes up quite a bit of spacetakes up quite a bit of space• random accessrandom access• don't sweat the details of how this worksdon't sweat the details of how this works

– tape drivestape drives• data stored in tracks (bits plus parity)data stored in tracks (bits plus parity)• prone to errors prone to errors • very cheapvery cheap• slow sequential accessslow sequential access

– disks (floppy, hard, laser etched)disks (floppy, hard, laser etched)• data stored in tracks and sectorsdata stored in tracks and sectors• may or may not be exchangeablemay or may not be exchangeable

– ROM's ROM's • read onlyread only• simplest form is a series of diodes which select a current pathsimplest form is a series of diodes which select a current path• in more complicated form, they are semiconductor memories which in more complicated form, they are semiconductor memories which

are programmed using high voltagesare programmed using high voltages• some are erasable using light or another voltagesome are erasable using light or another voltage• act like a big truth tableact like a big truth table

MemoryMemory

• 3. types of ROMS3. types of ROMS– mask programmedmask programmed

•mass producedmass produced•not field changeablenot field changeable

– Programmable ROMS (PROMs)Programmable ROMS (PROMs)•programmed by burning away a fusible linkprogrammed by burning away a fusible link•not changeable unless you change ones to zerosnot changeable unless you change ones to zeros

– Erasable PROMs (EPROMs)Erasable PROMs (EPROMs)•written by using high voltagewritten by using high voltage•erased by UV or electrically (EEPROMs)erased by UV or electrically (EEPROMs)