1 Lead Acid Batteries

If charging multiple batteries using constant voltage charging, how should the batteries be connected?

When multiple batteries are charged using this method they must be connected in parallel.

Electrolyte in a fully charged Lead Acid battery is approximately ____% water and ____% acid. In a fully discharged battery it is mainly __________.

70. 30. water.

What is in the bottom of a sump jar? and what is the purpose of the sumps jar?

A felt pad moistened with a neutralizing agent. Helps prevent damage to paint work should the electrolyte be expelled over board.

What would indicated a fully charge lead-acid battery?

A freely gassing battery exhibits rapid bubbling as gases leave the electrolyte, indicating a fully charged battery.

Batteries connected in series ___________ their terminal voltages and A/H rating is __________________.

Add. unchanged.

What should be checked before returning a stored battery to service?

Charge and capacity check

How does temperature affect the performance of the battery?

Cold temperatures slow down the chemical reactions and REDUCE THE CURRENT A BATTERY CAN DELIVER.

Describe constant current charging.

Constant current charging maintains an almost constant current during the entire charging process.

What is the consequence of using a constant voltage battery charger?

Constant voltage charging applies a constant high charging voltage across a battery. This results in high initial currents that can damage the battery if excessive.

What kind of water shroud be add to the battery?

Only pure distilled water should be used.

Using two batteries, how would you connect them to increase the Ampere Hour rating?

Parallel

The capacity of a battery is affected by four factors:

Plate area. Amount of active material. Quantity of electrolyte. Temperature.

The internal resistance of a battery ________ ________ ______________ when it is discharged during normal operation. This means the amount of ______________ it can supply is more than halved.

more than doubles. current

Batteries are rated according to ______________ _______________ ______________ and their ability to supply ___ ____________ __________ ___ _____________ for a given time.

nominal terminal voltage. a stipulated amount of current

How often should you capacity check a used battery?

3 months

How long must a batterie be able to supply emergency power while airborne for?

30 minutes

How often should a stored battery be charged?

4-6 weeks

What temperature should the battery never exceed?

48 degrees celsius

How often should you capacity check a new battery?

6 months

An individual Lead Acid cell usually charges up to ______ but is generally rated at ____ as it soon drops to this voltage.

2V and 2.2V

When the individual cells can be measured with the battery installed, the following test can provide a good indication of cell condition: (3 points)

- Crank the starter for three seconds. - Turn on loads of about ten amps. - Measure voltage of each cell.

Define Cold Cranking Amps

- Provides the maximum starting current a battery can provide. - For any given engine a minimum CCA figure is usually required for efficient starting. - The battery used for engine starting should at least match this figure.

Describe a Secondary Cell Battery.

- Rechargeable batteries - AKA storage batteries - Typically used in vehicles and aircraft.

Describe a Primary Reserve Cell Battery.

- Used in Life Vests. - Electrolyte stored separate to cell until activated. - Non-rechargeable.

Under what conditions should a lead-acid battery be stored in?

- cool, dry, well ventilated place. - on an acid resistant tray. Electrolyte levels should be checked and the battery charged before storage.

When hardware shows signs of arcing or overheating, what should be done?

- disassembled - cleaned - refitted - tightened to the specified torque.

Where are Primary Cell Batteries typically used? (2)

- emergency lighting - Emergency Location Transmitters (ELT's), and require periodic replacement.

not more than __________ Volts difference between cells.

0.05

Once you have charged the new battery how long should you wait before topping up the batter?

1 hour

Primary Cells consist typically different types of 5 different types of materials, what are they?

1. Carbon - Zinc Cells 2. Alkaline - Manganese Cells 3. Mercury Cells 4. Silver Oxide Cells 5. Lithium Cells

What are the two most common types of secondary cells?

1. Lead Acid Cells 2. Nickel Cadmium Cells (NiCad)

What are the three classes of batteries?

1. Primary Cell 2. Primary Reserve 3. Secondary

On the side facing the positive plate the Separators have vertical ribs/channels, what is the purpose purpose of this? (2)

1. permits the electrolyte to circulate freely around the plates. 2. provides a path for the sediment to settle at the bottom of the cell.

What precautions should be followed when cleaning the battery area?

1. use a soft bristle brush 2. make sure none of the solution enters the battery 3. vent caps must be on 4. vent holes sealed with tape 5. rinse the battery off with fresh water

Good cells should indicate ________ Volts each

1.95

How many cells would a 24 V battery have?

12 cells connected in series

How often should an insulation check be carried out?

12 months

If a battery cell has 6 cells each at 2V, What is its total voltage and why?

12V because each cell is connected to each other through series

Two 12V 40 A/H batteries connected in parallel supply ____V and ____ A/H capacity

12V, 80A/H

What is the maximum time you may store a battery for?

18 months

________ rates of charge or discharge ________ the plates causing ________________ of active material and possibly also ________________ discharge.

High. Heat. shredding. internal.

What type of electricity does chemical energy produce?

Direct Current

True or false? You must store lead-acid batteries in a discharged condition.

Do not store in a discharged condition!!!

What should be done to the battery before putting it back into service?

Electrolyte levels should be checked and the battery charged before storage.

What is an indication of overcharging?

Excessive water consumption

How would you describe the arrangement of the plates in a Lead-Acid Cell?

Interleaved, with each positive plate sandwiched between two negative plates. ( because of this, there will always be more negative plates than positive plates.)

What is the purpose of the separators in a Lead Acid Cell?

Keep positive and negative plates from touching each other

What are the positive plates made out of?

Lead Peroxide / Lead Oxide (Bothe PbO2)

What happens if you leave a lead acid battery in a low or discharge state for too long?

Leaving a battery in a low or discharged state for too long can also permanently damage it.

During charging a Lead Acid or Ni-Cad battery always generates hydrogen and oxygen gas. As this is an explosive mixture the following precautions should be observed:

Loosen vents to allow gas to dissipate. Charge in a well ventilated area. Do not connect charger clips to the battery terminals while live, as arcing may result.

How would you clean spilled battery acid?

Neutralise spilt acid with Sodium Bicarbonate solution and rinse with water.

Describe a Primary Cell Battery.

Not rechargeable, D Cell, portable appliances.

_______________________________________ for batteries are preferred as they protect the battery terminals from ________ by housing them in a recessed receptacle that is entirely enclosed when the aircraft connector mates with it. They do not require tools to be placed in direct contact with terminals, and also prevent wiring crossovers because they mate in the ________ ________ ___________.

Quick disconnect assemblies shorts correct polarity only

Primary Cell Batteries require periodic ______________________.

REPLACMENT

The Lead Acid Cell in a casing made out of what material?

Rubber or hard plastic.

What is the purpose of the sediment chamber?

Sediment chamber allows shed active material falling off plates to accumulate below them without shorting them out.

A "battery" is formed by a number of cells connected in ___________ and its ____________ is determined accordingly

Series. Terminal Voltage

What are the negative plates made out of?

Spongy lead

What is the electrolyte used?

Sulfuric acid and water

Define Terminal Voltage

Terminal voltage is the voltage output of a device is measured across its terminals.

Define Ampere / Hours (A/H)

The A/H rating states the theoretical current the battery can supply in one hour. The life of a battery from full charge can be calculated using this figure if the discharge current is known, for example a 40 A/H battery should provide 20 Amps for 2 hours or 10 Amps for 4 hours.

Secondary cells can be re-charged, what does this mean?

They can have there have their electro-chemical action reversed.

What does constant voltage charging have an advantage over constant current?

This method requires less time and supervision than constant current charging.

A typical rating for a Lead Acid battery might include: 12__, 40 ____________ __________, 400 ________ ________________ ________.

V Ampere Hours Cold Cranking Amps

Which is more susceptible to freezing, a charged battery or a flat battery?

a fully charged battery is less susceptible to freezing due to its increased density. (also there is more water when the battery is uncharged)

When a battery is charged the ________ ______________ and density of the ___________ increases.

acid content. electrolyte

What type of paint should be used for touch ups on the battery box?

acid resistant paint.

If an electrolyte is to be mixed for a dry shell what should be added first?

acid should be added to the water and not the other way round

What is the purpose of a vent cap?

allows escape of gas, and provides access for checking electrolyte levels.

What are most aircraft generating systems considered in terms of voltage?

constant voltage systems since the output voltage of the generator is held at a relatively constant level by a voltage regulator.

Where the battery uses standard exposed terminal posts or studs, care should be taken to ensure the earthed negative terminal is ____________________________________________________ to minimise the possibility of shorting the battery.

disconnected first and reconnected last

Constant voltage charging: As the battery charges, the current.....

drops off

Most new batteries are received in a __________-_____________ state with the cells sealed.

dry-charged

What is the standard rating used to specify the capacity of a battery?

five hour discharge rating.

Charging of batteries using constant voltage is achieved by connecting a voltage to the battery terminals that is slightly ____________ than the battery voltage.

higher

How are the plates of each polarity are connected?

in parallel and to a terminal post.

If you were to charge multiple batteries using constant current method, how would you connect them?

in series with current limited to the max current of the lowest battery.

In order to overcome battery ________________ __________________ and allow sufficient charge _______________ to flow the charging voltage must be sufficiently above the terminal voltage of the battery, i.e. 28V would be a typical charge voltage for a ____ volt battery.

internal resistance. current. 24

All circuits should be ___________ during connection or disconnection to ensure no ____________ occurs at the terminals near the battery cell vents due to the danger of explosive ________ being present.

isolated sparking gases

What level should electrolyte cells be maintained at?

just above the top of the cell plates

The electrolyte level should be such as to ________ __________ ______ ____________

just cover the plates.

Aviation Lead Acid batteries must be.....

kept at a high state of charge. (Starting of engines requires a high charge state.)

What kind of water is to be added to a battery?

only pure distilled water. any impurities will reduce the effectiveness of the chemical reactions.

What should exposed battery terminals be coated with to exclude moisture, prevent corrosion and the formation of deposits on the terminals.

petroleum jelly or general purpose grease

What is the purpose of the check valve between the sump and the battery housing?

prevents neutralising agent from finding its way into the battery compartment and contaminating the BATTERY ELECTROLYTE

In terms of the two vents: One acts as a "______-______" vent causing a ________________ ______ ________ through the battery and out through the flush mounted "______________ ________".

ram-air. positive air flow. battery vent

What could cause over charging?

result of a defective cell or internal short.

The electrolyte must be added to the cells and the battery given a ..........

slow refreshing or boost charge.

What solution should be used to clean the area around the battery?

sodium bicarbonate solution

As a battery discharges, ________________ forms on the outside of the plates. Not only is the amount of active material ______________, but the remaining ______________ ________ available for the electrolyte to react with is also reduced by the blocking effect of the sulphate. This effectively increases the ________________ __________________ of the battery which in turn ______________ the amount of current it can still deliver.

sulphate. reduced. internal resistance. reduces.

Excessive discharge of a Lead acid battery results in excessive ____________________.

sulphation

Excessive _____________________ renders the battery incapable of delivering further current and may also make _____________________ difficult. For this reason ______________ __________________ ____ __________ is to be avoided

sulphation. recharging. extreme discharge of Lead Acid batteries

Any noticeable differences between cell voltages indicates?

there is a defective cell in the battery.

What is the purpose of the proactive coating / tray that the battery is sat on?

to contain electrolyte spills

What is the purpose of having a positive airflow source in the area where the battery is housed?

to extract battery gases and electrolyte spillage

When and Why does constant current current charging require more supervision?

when the battery is almost fully charged, to avoid over charging since the charge voltage continues to increase to maintain current.