Im sorry

sayang, kita gaduh lagi -.-"

penat la gaduh2 ni. sakit hati, sakit kepala, sakit badan.. semua lah sakit.

saya tak suka lah kita gaduh.

yayaya,

saya tau mesti sayang kata semua nya salah saya,

bukan sayang yang start everything.

memang lah sayang tak start everything but saya yang memikir benda yang bukan2 about you my dear.

im sorry?

malu la nak cakap sorry sayang. yeah

sepanjang kita kapel, banyak kali dah kan saya buat sayang macam ni?

sangat banyak kan?

sampai tak terkira banyaknya,

and the worst part is, lepas saya dah mintak maaf saya akan ulangi perbuatan tersebut juga.

sayang, bukannya saya xpercaya dekat sayang,

but i need a concrete relationship, yang share everything

haish,,

yala2 mungkin age different kita yang sangat jauh membuatkan saya tak paham kehendak sayang, and sayang xpaham kehendak saya.

but still sayang its not because i dont trust you, its just i wanted to know who you really are :')

yeah3, maybe you'll say that is a lame reason,

but you dont have a solid reason to act like that.

its fair lahh.

but still i cant understand you walaupun kita dah berbaik.

yeahh,

betul, cant really understand your reason rasa macam nak tumbuk2 sayang bila ingat balik,

arggggggggggggggghhhhhhhhhhhhhh

xpa la, asalkan kita bahagia :'(

sayang selalu kata love should be happy, tapi sayang , macam mana saya nak happy?

entahla, niat nak reda kan perasaan, but ingat balik buat rasa geram

hishhhh.

sayang, tak suka la sayang ni.

suka buat macam ni.

mmphh

tak tau la sampai bila bole bertahan this relationship

hopefully it will last smpai ke anak cucu.

i love you sayang.

DC SOURCES OF ELECTRICITY

batteries is divided into two groups

• primary cell ( dry cell / leclanche cell )
• secondary cell

now we are going to discuss about secondary cell

SECONDARY CELL.

-known as storage cell.

-any kind of electrolytic cell in which the electrochemical reaction that releases energy is reversible.

-must be charged before used.

-examples of usages :

• laptop
• handphone cell

types of secondary cell

• LEAD ACID CELLS
• NICKEL CADMIUM CELL ( NiCAD )

LEAD ACID CELLS

purpose :

• power supply to aircraft during emergency and starting.

construction:

• +ve plate used lead peroxide fill with antimony
• -ve plate used spongy lead and has extra plate than +ve plate
• electrolye is dilute sulphuric acid with water 30% acid and 70% water
• casing made up of high impact plastic
• vent screw type which allow distilled water to adjust electrolyte level.
• separator prevents +ve and -ve plate from touching but allow sulphuric acid to pass through.
• 6 / 12 cells, each cell rate 2.1 volts.

indication of fully charged condition:

-terminal voltage

• 2.7V/ cell on charged
• 2.1 V/ cell off charged
• 1.8 V/cell discharged
  

terminal voltage between 30.0 to 32.4 V ( on charge ), if terminal voltage below 28.5 V , it should be withdrawn from service.

voltage test :

• specific gravity of electrolyte - 1.275 and 1.300 at 80. use hydrometer to check
• gassing freely

fully discharge

• sulphation occur and electrolyte become water.
• S.G will be low (1.150) due to internal resistance becomes high.
• both plate becomes white lead sulphate : act as high resistance
• sulphation occurs when battery discharged

capacity

• ability to produce a given amount of current for specific time e.g 1A for 1 Hour
• more than 80% efficiency fit for aircraft use

efficiency (%) = output capacity / rated capacity X 100

factor affecting capacity of a battery :

• num of plate
• plate area
• strength of electrolyte
• temperature

proper servicing is required on this cell :

• keep battery clean , all terminals tight and free of corrosions.
• electrolyte level should 1/4 above the plates , if low add distilled water and not acid.
• when mixing electrolyte always add ACID to WATER.
• coat the battery terminals with petroleum jelly or general purpose grease in order to prevent corrosion or oxidization on the terminals.

two types charging :

- Constant current charging

• most effective
• charge battery by supplying current at a constant rate ( manually )
• when charging more than one battery, it must be connected in series and battery voltage must not exceed the charging voltage.
• several batteries in series , charge at the lowest battery capacity.
• need monitoring during charging
• temperature must not exceed 60 C as for the electrolyte it must be below 43C
• when cells commence gassing, the voltage and relative density should be measured periodically.

-Constant voltage charging

• when battery connected in an aircraft , car or a other vehicles
• generating voltage system slightly higher than battery voltage
• the amount of current flow into a battery is determined by the state charge of battery.
• no need monitoring device

capacity test :

• carried out after initial charge
• carried out 3 monthly
• at any time if capacity in doubt
• acceptable capacity for use in aircraft is 80% and above

insulation test :

• carried out at a periodic of time
• at any time the electrolyte suspected leakage.
• place a fully charged battery on metal plate , test between terminal and plate using 250 V insulation tester ( megger ), reading must not less than 1 Mili Ohms.

storage :

• stored clean, dry, well ventilated area
• always stored in fully charged condition this is to prevent sulphation to occur.
• give re freshening charged every 2 to 4 weeks.

safety and precaution :

• lead acid and Nicad cell must be stored in separate room.
• do not wear rings, or metal strap.

to be continued......................