Designed & Created By Ralph Coco

BIGGEST PROBLEMLack of understanding and many misconceptions

regarding battery design and performance!

In most cases after being installed, batteries are unseen and forgotten.

Batteries are locked away inside a cabinet, so they are out of sight and out of mind.

FACP

SOLUTIONEducation is key.

Understanding batterys characteristics and how they operate will go a long way towards improving their design.

Created by by Alessandro Volta in 1800.

This arrangement was known as a voltaic pile.

ZincBlotting Paper in Salt Water

SilverZinc

Blotting Paper in Salt Water

ZincSilver

Blotting Paper in Salt WaterSilver

By attaching a couple of wires at the top & bottom of the pile, a voltage could be measured.

Alternating layers of Zinc & Silver between blotting paper soaked in salt water.

Sealed Lead Acid available in 2 main types

Gelled Electrolyte Systems.

Silica is added to convert the diluted sulfuric acid into a gel. (Gel Cells)

Absorbed or Retained Electrolyte Systems

The Separator is absorbent and retains the electrolyte. (Not free flowing, but similar to a wet diaper. Also referred to as Starved Electrolyte Systems .

TWO TYPES OF SEALED LEAD ACID BATTERIES

SEALED LEAD ACID

Lead Oxide paste is added to the positive plate to form the electrically active material.

The negative plate paste is made of pure lead.

Both plates are porous and spongy to optimize surface area.

Cast grids, made of lead calcium alloy mixed with tin for tensile strength.

SEALED LEAD ACID

Separator acts like a sponge soaking up the electrolyte. It is also designed to be a good insulator.

The electrolyte is immobilized diluted sulfuric acid.

Micro-porous Glass Fiber Separator is sandwiched in between the plates.

SEALED LEAD ACIDIn a 12 Volt Battery the cells are arranged into 6 cells of 2 Volt arrays.

SEALED LEAD ACIDPlates are packaged in a plastic container. (ABS, Styrene, Polypropylene or polyethylene)

Separators filled with immobilized diluted Sulfuric Acid (Electrolyte).

Leak-proof design for operational safety & transportation.

One way sealing vent in case of gas build-up. The relieve valve will open to release the pressure 2-6 psi.

During Discharge Sulfuric Acid is absorbed into the plates & converts the lead dioxide on the positive plate and pure lead on the negative plate to lead sulfate, water and energy.

Sulfuric Acid in separator

Pure Lead

Lead Dioxide

Energy

Water

Lead Sulfate

Lead Sulfate

SEPARATOR

Water

Lead Sulfate

Lead Sulfate

During Recharge, an external energy source is applied to convert Lead Sulfate and Water back to Lead, Lead Oxide, and Sulfuric Acid.

Sulfuric Acid in separator

Pure Lead

Lead Dioxide

External Energy Source Is Applied

SEPARATOR

To produce a truly maintenance free battery, it is necessary that the gases generated during overcharge are recombined in a so-called oxygen cycle Should oxygen and hydrogen escape, a gradual drying out would occur, eventually affecting capacity and battery life.

Positive Plate

Produces Oxygen

Negative Plate

Produces Hydrogen

The Hydrogen and Oxygen gases are

recombined back to form water stored in

the separator

SEPARATOR

VOLTS PER CELLThroughout this presentation we are going to use the term volts per cell. (VPC)

Each cell in a lead acid battery is rated at 2 volts nominal.

A 24 volt battery has 12 cells X 2 volts = 24 volts.

The VPC number facilitates voltage calculations because its value can be used on any size battery, irrelevant of the batterys voltage.

Example Charging voltage is 2.30 VPC- A 12 volt battery has 6 cells. A charging voltage of 2.30 VPC = 2.30 VPC X 6

cells = 13.8 volts)

- On a 24 volt battery (Fire Alarm) the charging voltage would be 27.6 volts (2.30 VPC X 12 cells = 27.6)

(C) RATED CAPACITYManufacturers use a C (Capacity Rating) as a percentage of the batterys overall capacity.Example 20 A.H. BatteryWe will discharge it at the .05C rate..05C = 5% of the batterys overall capacity On a 20 A.H (5% of 20 is = 1 amp) .1C (10% of 20 A.H. = 2 amps.5C (50% of 20 A.H. = 10 amps)1C (100% of 20 A.H. = 20 amps)

BASIC BATTERY CHARACTERISTICS

CONNECTING IN SERIES

12 Volts

20 AH

36 Volts

20 AH

48 Volts

20 AH

24 Volts

20 AH

Connecting Batteries in series Battery voltage increases / Capacity remains the sameCharging in series All batteries in the string will receive the same amount of charge current, but individual battery voltages may vary

Never mix batteries of different capacities, make or age in a series string. Differences in capacity can cause some batteries to overcharge while others remain undercharged.

CONNECTING IN PARALLEL12 Volts

20 AH

12 Volts

60 AH

12 Volts

80 AH

12 Volts

40 AH

Connecting Batteries in parallel Battery current increases / Voltage remains the sameCharging batteries in parallel All batteries in the string will receive the same amount of voltage, but the charge current each battery receives will vary until equalization is reached

A battery is fairly efficient in accepting charge up to approximately 75% of its rated capacity.

In a 20 A.H. Battery the efficiency is fairly good up to about 15 A.H.

From 15 A.H. to 20 A.H; battery charging then becomes inefficient where more energy and time is required to charge the battery to 100% of its rated capacity.

During this period of time, a greater amount of electrolyzing of water takes place.

Ch

arg

e E

ffic

ien

cy %

State of Charge (%)

0 100

100

50

50 75

A Battery also requires approximately 20% of overcharge (in excess over capacity discharged) in order to become fully recharged.

20 A.H. Battery would require 24 amps to become fully charged

CALCULATING RECHARGE TIMEStep 1 - Batterys Capacity (AH) divided by the rated output of the charger (amps)Step 2 - Multiply the resulting number of hours by 1.75 to compensate for the declining output current during charge

20 AH / 2 AMPS = 10 Hours 1.75 = 17.5 HoursX

20 AH / 2 Amps = 10 hours

The open circuit voltage when fully charged is around 2.15 V/Cell

(2.15 VPC x 12 cells = 25.8 Volts on a 24 volt battery).

Completely discharged is 1.94 V/Cell (23.28 Volts on a 24 volt battery).

Under load the battery can deliver useful energy at less than 1.94 V/Cell, but after load is removed voltage will bounce back up.

To fully charge a 24 volt battery, a DC voltage higher than the open circuit voltage of 2.15 (25.8 Volts) must be applied.

The end voltage can be defined as the point at which 100% of the usable capacity has been consumed.

Or the continuation of discharge is useless because the voltage drops below useful levels for the equipment to operate.

To optimize Battery Life, it is recommended that the battery be disconnected from the load when the required end voltage is reached.

CRITERIA FOR DETERMINING A FULLY CHARGED BATTERY

1) The final current level flowing into the battery.2) The peak charging voltage while this current level flows.

Example

1a) Final Current level should be less than 1% of rated capacity. This level is normally around .1% or .001C.

1b) On a 20 A.H. battery = .02 amps or 20 milliamps. (.001C = .1% rated capacity).

2) Peak charging voltage on a fully charged battery = 27 to 27.6 volts.

On a 24 volt 20 A.H. Battery the two magic numbers are, a final flow current of 20 milliamps and a float voltage of 27.6

FACTORS AFFECTING BATTERYS LIFE & PERFORMANCE

TEMPERATUREAt 68 F (20 C) rated capacity is 100%.

Capacity will increase slowly above this temperature and decreases as the temperature falls.

Raising ambient temperatures increases capacity, but it also decreases useful service life.

It is estimated that battery life is halved for each 10C above normal room temperature.

At (35 C) capacity increases, but batterys life is cut in half.

EFFECTS OF TEMPERATURES ON BATTERYS CAPACITY

0

20

40

60

80

100

120

-20 -10 0 10 20 30 40 50 60

Temperature

Cap

acity

Rat

io %

.05C

At 20 C and discharging at the .05C rate, 100% capacity is availableAt -20 C only 65% capacity is availableAt -20C, the battery would need to be oversized by 55% to

provide the same capacity (20.A.H.) as it would at 20C. A 31 A.H. battery would be required.

After reaching full charge excessive current will flow into the battery causing decomposition of water in the electrolyte and hence, premature aging. Important to set-up your charger properly for each application.

Charging Voltage should not exceed 2.45 V/Cell = 29.4 Volts (2.45 VPC is used on Cyclic Applications for a faster recharge time - Standby Application = 27.6 volts)

Initial Charge Current should not exceed 0.2C = 20% of rated capacity

When at a charge voltage of 2.45 V/Cell (29.4 Volts) and the battery is fully charged, the charger voltage should be switched to a float level of 2.25 to 2.30 V/Cell = 27 to 27.6 Volts

If too low a charge voltage is applied, the current flow will essentially stop before the battery is fully charge

This allows some of the lead sulfate to remain on the plates which will eventually reduce capacity

BATTERY LIFE

0

20

40

60

80

100

120

0 200 400 600 800 1000 1200

Number of Cycles

Cap

acity

(%)

100%50%30%

Depth of Discharge

100%

Depth of Discharge

50%

Depth of Discharge

30%

1. Discharge Current: 0.2C (4 Hour Rate)

2. Final Voltage: 1.7V/Cell

3. Charge Current: 0.1C

4. Ambient Temperature: 20C to 25C

Depth of Discharge vs. Number of Cycles

0

20

40

60

80

100

0 1 2 3 4 5

Years

Ret

entio

n C

apac

ity

Float Charging Voltage

2.25 2.30 V/Cell = 27 to 27.6 Volts

End of life is 4 to 5 yearsThis is a non-cycling application where the battery is mainly on standby mode

SHELF STORAGE LIFE

0102030405060708090

100

0 2 4 6 8 10 12 14 16 18 20

Storage Period (Months)

Cap

acity

Ret

entio

n R

atio

% Charging is not necessary unless 100% of capacity is required

Charging before is necessary to recover full capacity

Charge may fail to restore full capacity. Do not let battery ever reach this state

40C (104F) 30C (86F) 20C (68F)

5C (41F)

Self Discharge Characteristics

BATTERY STORAGE Do not store batteries in elevated temperatures or in a

discharged state

Elevated temperatures reduce shelf life

To prolong shelf life without charging, store batteries at cooler temperatures.

Recharge a stored battery every 6 9 months.

AIR SPACETo prevent problems arising from heat exchange

between batteries, it is advisable to provide air space of at least (.4) (10 mm) between batteries

NEVER CHARGE OR DISCHARGE A BATTERY IN AN AIRTIGHT ENCLOSURE

Batteries generate a mixture of gases internally. Given the right set of circumstances such as extreme overcharging, these gases might vent into the enclosure and create the potential for an explosion when ignited by a spark

There are a variety of different charging methods

Taper Charging:

Constant Current

Constant Voltage

Constant Float Charging

Two Step Constant Voltage

Combinations of the above

SELECTING THE APPROPRIATE CHARGING METHOD

Selecting the appropriate charging method depends on the intended use of the battery.

Is the battery being used in a Cycling Application or Float Service?

Other factors to considerRecharge timeDepth of dischargeExpected service lifeCost of charger design

The Battery is infrequently called into service. Therefore, it is considered to be a standby application

Constant Float Voltage Charging is highly recommended in standby applications where battery recharge time is not required to be as fast or as frequent as in cycle operation.

This charging method applies a constant voltage, but allows the battery to define its own current level and remain fully charged without having to disconnect the charger.

The recommended constant float voltage is 2.25 to 2.30 V/Cell = 27 to 27.6 Volts.

The trickle current for a fully charged battery will hover around the .001C rate (.1 % of the rated capacity) 20 ma for a 20 AH Battery.

C Rate % of Capacity

Amps

1C 100% 20

.1C 10% 2

.01C 1% .2 (200 ma)

.001C .1% .02 (20 ma)

The trickle current for a fully charged battery will hover around (.1 % of the rated capacity).

CONSTANT FLOAT VOLTAGE CHARGING

20

21

22

23

24

25

26

27

28

29

30

0 5 10 15 20 25

Charge Time (hr)

Bat

tery

Vol

tage

Cha

rge

Cur

rent

Am

ps

4.5

4.0

3.5

3.0

2.0

1.5

1.0

0

Battery 20 AH - Charge Voltage 27.6 Volts

Charge Current = .1C = 10% capacity (2 amps)

Battery Voltage 27.6 Volts

Charger Current .1C = 2 amps

Initial Current starts at 2 amps, but gradually decreases as the battery charges

Battery Voltage increases to its set float Charging level of 27.6 Volts

When battery is fully charged the trickle float current = .001C or .1% of capacity = 20 ma on a 20 A.H. Battery

Fully Charged

The charger shall be capable of recharging the battery following a discharge equal to the batterys rated load cycle so as to provide, in a charging time of 12 h, battery capacity of 70% of rated load cycle. (100% in 48 h) (Proposed is 80% in 24 h 100% in 48 h)

Rated load cycle is the maximum possible Supervisory Current plus the Trouble Signal Current (Alarm Load)

Manufacturers will need to meet ULC Standard S527 Clause 9.5.5.2

ULC-S527 STANDARD FOR CONTROL UNITS FOR FIRE ALARM SYSTEMS

Storage Batteries Clause 7.8.8

Battery Tests Clause 9.5

ULC-S524 STANDARD FOR INSTALLATION OF FIRE ALARM SYSTEMS

Batteries Clause 3.2.5

OBC (Ontario Building Code) NBC is equivalent in its requirements

Emergency Power for Fire Alarm Systems Clause 3.2.7.8

a) Generator

b) Batteries

c) Combination thereof

ULC-S537 Verification

Clause 4.4.4

ULC-S536 Annual Test & Inspection

Clause 5.3.2

ONTARIO BUILDING CODE3.2.7.8. Emergency Power for Fire Alarm Systems

(1) Fire alarm systems, including those incorporating a voice communication system, shall be provided with an emergency power supply conforming to Sentences (2) to (4).(2) The emergency power supply required by Sentence (1) shall be supplied from,(a) a generator,(b) batteries, or(c) a combination of the items described in Clauses (a) and (b).(3) The emergency power supply required by Sentence (1) shall be capable of providing,(a) supervisory power for not less than 24 h, and(b) immediately following, emergency power under full load for not less than,(i) 2 h for a building within the scope of Subsection 3.2.6., (Commercial High Rise Buildings greater than 36 metres; Hospitals, Prisons, Nursing Homes greater than 18 metres)(ii) 1 h for a building classified as Group B major occupancy that is not within the scope of Subsection 3.2.6., (Institutional Buildings less than 18 metres)(iii) 5 min for a building not required to be equipped with an annunciator, and(iv) 30 min for any other building.(4) The emergency power supply required by Sentence (1) shall be designed so that, in the event of a failure of the normal power source, there is an immediate automatic transfer to emergency power with no loss of information.

UNDERSTANDING CAPACITYCapacity, expressed in ampere-hours (AH) is the product of the CURRENT DISCHARGED and the LENGTH OF DISCHARGE TIME

2 amps of constant current X 10 hours = 20 A.H.

CONSTANT CAPACITY?Will a 20 A.H. battery provide 20 amps of current output irrelevant of the discharge rate?Yes, but only when the appropriate amount of current is discharged for a specific time period. Batteries are designed to perform their duties using hourly ratings. Example - Some batteries are rated at the 20 hour rate whereas others are at the 8 hour rate, so it is very important to look at the manufacturers tables.To understand this better, we will look at an example using data from a manufacturer.

Rated Capacity

0.05C rate (20 Hr Rate)

0.1C rate (9Hr Rate)

0.2C rate (4 Hr Rate)

0.5C rate (1.3 Hr Rate)

1C rate (33 Min Rate)

2C rate (12 Min Rate)

3C rate (7.2 Min

Rate)

2O AH 1.00 20.00 2.00 18.00 4.00 16.00 10.00 13.00 20.00 11.20 40.00 8.00 60.00 7.20

40 AH 2.00 40.00 4.00 36.00 8.00 32.00 20.00 26.00 40.00 22.40 80.00 16.00 120.00 14.40

100 AH 5.00 100.00 10.00 90.00 20.00 80.00 50.00 65.00 100.00 55.00 200.00 40.00 300.00 36.00

Rated Capacity

0.05C rate

(20 Hr Rate)

1C rate

(33Min Rate)

In the first example, we are going to discharge a 20 A.H. battery rated at the 20 Hr rate.Next we are going to increase the current load to 1C = 100% of rated capacity. This is 100% of the batterys capacity = 20 amps.

Due to the increased current load, our discharge time is shorter and AH capacity is affected. (20 AH battery now becomes an 11.2 AH battery)

To achieve a 20 amp discharge for one hour, a 33 A.H. Battery would be required. (65% more capacity)

Batteries are not a continuous power source. They are affected by amperage loads, voltages and temperature.

When a battery discharges at a constant rate, its capacity changes according to the amperage load.

When the constant current load decreases, the available capacity will be higher.

When the constant current load increases, the available capacity will be lower.

It is very important to follow the batterys hourly rating and Manufacturers discharge tables.

BATTERY SIZING EXCERCISE

CALCULATE SUPERVISORY & ALARM LOADS

Supervisory = 0.5 amps for 24 hoursAlarm = 3.0 amps for 30 minutes

FACP

TYPICAL FIRE ALARM SYSTEM LOAD PROFILECalculated Supervisory Load = .5 amps X 24 hours.

For discharge times longer than 8 hours use straight multiplication formula (.5 Amps X 24 Hours = 12 A.H).

Calculated Alarm Load = 3 Amps for 30 minutes.

For discharge rates less than 8 hrs, please refer to manufacturers Tables. Manufacturers Capacity table selects a 3 AH battery.

00.5

11.5

22.5

33.5

44.5

5

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Time Hours

Current Amps

Add up both loads (12 AH + 3 AH = 15 AH)

A good practice is to always add 25% capacity to the battery. (15 AH X 25% =18.75 AH or closest AH capacity)

12 AH

3 AH

Helps compensate for battery aging.

Allows the battery to perform the full load cycle near end of life.

Improves recharge efficiency.

The additional capacity improves low temperature operation.

Increases overall battery performance (Shelf Life - Deep Discharge Cycle Life)

OVER SIZING THE BATTERY BY 25%

TESTING ULC-S536 PART 15.3.2 Each battery shall be inspected and tested to confirm operability, including the following functions, as applicable (Refer to Appendix E2.5, Emergency Power Supply Test and Inspection.):

A Correct type as recommended by manufacturer;B Correct rating as determined by battery calculations based on full systemload;C Voltage with main power supply on;D Voltage and current with main power supply off and the fire alarm systemin supervisory condition;E Voltage and current with main power supply off and the fire alarm systemin full load alarm condition;F Charging current;G Physical damage;H Terminals cleaned and lubricated;I Terminals clamped tightly;J Correct electrolyte level;K Specific gravity of electrolyte within manufacturers specifications;L Electrolyte leakage;M Adequate ventilation;

TESTING ULC-S536 PART 1

Make sure it is a good quality (sealed maintenance free) or (wet cell) battery, manufactured by a reputable company. Please follow manufactures tables and curves when sizing batteryAfter calculating full system load you will know whether the battery is sized correctly. (8 A.H. or 12 A.H.?) Look for A.H. markings on the battery27 to 27.6 volts should be the recharge voltage. (Some panels have a variable charging algorithm) Please check with FACP Manufacturer for charging characteristics)

This can be measured. Please keep in mind that open circuit voltage on a fully charged battery = 25.8 volts. The voltage will decrease as capacity is consumed

This can be measured. Please keep in mind that voltage will have decreased after 24 hours of supervisory load

The charging current will vary. Please make sure that the charging current does not exceed 20% of the batterys rated capacity. When fully charged, the trickle float current should be at around .1% of rated capacityVisual inspection. Please look for plate expansion (pregnant battery)

Applicable on Wet Lead Acid Battery (Free Flowing Electrolyte)

Applicable on Wet Lead Acid Battery (Free Flowing Electrolyte)

Visual Inspection

The battery enclosure or FACP should have ventilation holes (openings) for air circulation. Battery spacing = 10mm apart

TESTING ULC-S536 PART 2N Record the battery manufacturers date code or in-service date;O Disconnection causes trouble signal; andP Perform battery tests demonstrating specified battery operation as follows,after which the battery voltage should not be less than 85% of its ratingafter the tests, otherwise replace batteries (Refer to Appendix F, BatteryTests):(i) Required supervisory load for 24 h followed by the required full loadoperation; or(ii) A silent test by using the load resistor method may be used for the fullduration test (Refer to Appendix F1, Silent Test); or(iii) Silent accelerated test. (Refer to Appendix F2, Silent AcceleratedTest); or(iv) A battery capacity meter test. (Refer to Appendix F3, Battery CapacityMeter Test); or(v) In lieu of the above battery tests, replace the battery with a new sethaving a current date code, amp-hour capacity and type asrecommended by the manufacturer.

TESTING ULC-S536 PART 2

After the battery has been cycled through its supervisory and alarm load profile, the terminal voltage must not fall below 85% of its nominal voltage. = 20.4 volts (End voltage = 1.7 VPC)

We are provided with various options regarding load testing. Battery capacity meter testing will provide some indication regarding the batterys health, but not the whole story. The only accurate way of knowing whether a battery will perform the duty cycle is to exercise it through that load condition

This is our escape clause. If in doubt or battery testing will not be economical then replace the battery

Look for a manufacturers date code or installation date. Sealed batteries should be replaced every three years

THE END&

THANK YOU

Slide Number 1BIGGEST PROBLEMSOLUTIONSlide Number 4Slide Number 5Slide Number 6Slide Number 7SEALED LEAD ACIDSEALED LEAD ACIDSEALED LEAD ACIDSEALED LEAD ACIDSlide Number 12Slide Number 13Slide Number 14VOLTS PER CELL(C) RATED CAPACITYBASIC BATTERY CHARACTERISTICSSlide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24CRITERIA FOR DETERMINING A FULLY CHARGED BATTERYFACTORS AFFECTING BATTERYS LIFE & PERFORMANCE TEMPERATUREEFFECTS OF TEMPERATURES ON BATTERYS CAPACITYSlide Number 29Slide Number 30BATTERY LIFESlide Number 32SHELF STORAGE LIFESlide Number 34Slide Number 35Slide Number 36Slide Number 37SELECTING THE APPROPRIATE CHARGING METHOD Slide Number 39Slide Number 40CONSTANT FLOAT VOLTAGE CHARGINGSlide Number 42Slide Number 43Slide Number 44Slide Number 45CONSTANT CAPACITY? Slide Number 47Slide Number 48Slide Number 49CALCULATE SUPERVISORY & ALARM LOADSSlide Number 51Slide Number 52TESTING ULC-S536 PART 1TESTING ULC-S536 PART 2Slide Number 55