Battery

UNKNOWN
Difference btw lead acid and Alkaline battery
Lead acid

+Ve plate lead peroxide PbO2
-ve terminal lead
Electrolyte dilute sulphuric acid
During discharge,
the electrolyte dissociate and hydrogen ions reacts with oxygen dissociated from lead peroxide and forms water.
PbO2 + H2 + H2SO4 -->PbSO4 + 2H2O
At negative plate,
Pb + SO4- --> PbSO4
After DISCHARGED
Voltage – 1.75V
Sp gr – 1.110

During Charging
At negative plate
PbSo4+H2 --> Pb+H2So4      AND accumulated sulphate So4 returns to the solution.
The H2O breaksdown to return H+ to the solution and  the oxygen recombine with pb and form PbO2
PbSo4 + 2So4+ 2H2O --> PbO2 + 2H2So4
Provided with a vent and releases gases only when nearing the top of the charging
Fully charged
Voltage 2v
Sp gravity – 1.285 @ 15degrees

Produces 2v per cell
Takes time for charging
Less life 5yrs
Preferred for regular recycling
Life considerably reduce above 25degrees

Nickel Cadmium
+ve plate Nickel hydrate with small % of graphite to increase conductivity
-ve terminal – mixture of Cadmium and iron
Electrolyte strong alkaline KOH with an addition of lithium hydroxide(1-2%) to minimize the coagulation of nickel hydrate electrode on cycling and increase the electrolyte resistance.

During discharge,
Nickel hydrate releases hydroxyl ions n becomes nickel hydroxide
Ni(OH)4+2K --> Ni(OH)2+2KOH
Cd+2(OH) --> Cd(OH)2
Hydroxyl ions combine with the Cd and form cadmium hydroxide
Since the hydroxyl are passed from one plate to another, no change in sp gravity of the electrolyte….. hence state of charge is not known by electrolyte sp gravity.
Continuously evolve gases, oxygen at the positiveplate and hydrogen at negative plate.
Provided with a non retun vent so that the electrolyte doesn’t come in contact with Carbon dioxide in air and form potassium carbonate.
Discharged
Voltage   1.09V

DURING CHARGING
Ni(OH)2+2(OH) --> Ni(OH)4
Cd(OH)2 + 2K --> Cd+ 2KOH
1.2V
Renewal reqd wen sp gravity drops to 1.170

Produces only 1.2v per cell. So more wt for same rating
Quick charging due to less resistance
More life 10-15yrs
Can be used for keeping it idle for long time
Can operate continuously at 45degrees
SEALED Ni-Cd batteries donot have vent caps and are sealed and maintenance free n donot require topup. Negative plate is made with surpus Cd(OH)2 so that it is only partially charged when the positive plate is fully charged. Since the active material is still available while charging, no production of hydrogen gas
Oxygen is produced in positive plate
4OH- -->2H2O+2O2+4e-
This reaction reverses at the negative plate replacing hydroxyl ions.

SARKAR BATTERIES
Criteria for renewal of batteries
Lead acid
Relative density/ sp gravity is 1.285   normal      reduces to 1.110
Normal 2v &  @ disch volt – 1.75V
End charge is indicated when the terminal voltage is 2.6V
Ni-Cd battery
Voltage 1.2v/cell discharge – 1.09
Rel density of a new cell– 1.190-1.210 at 15degrees
Replaced or electrolyte replaced at 1.145/1.170
End charge is indicated when the terminal voltage is 1.7V

Lead acid battery maintenance and about hydrometer?
Terminals Clean and dry. Use petroleum jel on the terminals to prevent corrosion
Terminal connection tight.
Secured in a wooden tray
Electrolyte proper level of atleast 1/8” higher than the top end of plates
Vents clean of deposits
Check container for deformation
Donot charge @ high rate – cos voltage of fully charged is a variable qty which varies  with rate of charging, the temp and sp gravity. Hence only hydrometer is used to check the state of charge of the battery
Donot keep the battery in a discharged condition for a long time. – lead sulfate formation on the plates and cannot be connected to active material.
Atleast once in a month fully discharge and charge again
HYDROMETER
Checking sp gravity with hydrometer for lead acid battery. Hydrometer is used to check the state of charge/relative density/sp gravity. The low readings of the hydrometer are at the top of the float and the high readings at the bottom.For every temp increase above 15degrees, then add 0.007 to the reading

Battery room safety with Exd? 25,30 and 243
Non sparking type Exh fan with its motor outside the ventilation passage and independent of other ventillation system, ventilation outlet on the top.
Ventilation duct of corrosion resistance paint
Flameproof lighting fitting
Voltage drop test of battery?
The condition of the battery is tested by discharging the battery at its rate for 10hrs (means 25A for a 250AH rating), the voltage drop shud not exceed 12.5% of the nominal system voltage after the test.
Voltage variationshud be within the limit of +10% to -12.5%
Unit of battery capacity?
Ampere-hours
A ship's battery capacity is usually rated in terms of its discharge at the 10-hour rate
How to check output voltage of emergency battery?
Battery what all checks.
trickle charging.
Float charging will charge the battery drains/loss due to load and has a circuitary to prevent overcharging
Trickle charging is set to constant current supply when the battery is in stdby to supply enough which compensates the leakage current
How to connect battery from 220V to battery charging connection?
How batteries are connected together, draw diagram, how much volt of one battery?
Battery ratings on ship voltage?

BHATTA BATTERY
Sulphanation in battery?
In a lead acid battery while discharging, at the negative terminal, pb reacts with SO4 to form amorphous lead sulphate.
During use, small crystals of lead sulphate is common and not harmful. During prolong charge deprivation, however, amorphous lead sulphate converts to a stable crystalline that deposits on negative plates. Sulphation lowers charge acceptance
Battery room ventilation and blade material?

Advantages and disadvantages of lead acid and alkaline batteries, where used onboard?

Few numbers of batteries are given to you, what factors you will consider for connecting them? 29 (voltage and amp-hr. for voltage in series and amp-hr in parallel)
Battery type of connection?
Polarization in battery?
Battery ordering, meaning of amp-hr, can a battery of 350amps, be used for 70amps and 5 hours?
Life boat battery charging system from where u will get the connection. What is the input and output value?

BATTERY CAPACITY TEST PROCEDURE
Battery capacity is expressed in Amp Hr .
It is measured how much AH it can deliver before its voltage drops down to end of discharge. The disch current must be constant during the entire process.
The test time tables gives the disch current and terminal voltage for the selected time period of testing.
Normally the test is carried out for 5/8 hrs. time is inversely prop to current.
At the end of discharge, the terminal voltage drops to 1.75-1.8V

If the battery reaches its terminal voltage before the mentioned time, then the battery capacity reduced and has to be discarded if the capacity reduced below 80%(As per IEEE- Inst of Electrical and Electronic Engineers)
If the battery capacity is sufficient but not within the time limit, theen also discarded

BEFORRE TESTING
Remove the charging connection. Check the battery and cell terminal voltage. Check sp gravity of the lead acid battery.