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Subelement I
Power Sources
Section 60
Batteries-1
When a lead-acid storage battery is being charged, a harmful effect to humans is:
  • Internal plate sulfation may occur under constant charging.
  • Emission of oxygen.
  • Emission of chlorine gas.
  • Correct Answer
    Emission of hydrogen gas.

When a lead-acid storage battery is being charged, a harmful effect to humans is:

Emission of hydrogen gas

Charging the lead-acid battery will release hydrogen gas, but also create sulfuric acid as hydrogen sulfide in the battery fluid. Ventilation is key.

For comprehensive list of issues associated with charging lead-acid batteries, please see the Battery University site, article BU-703: Health Concerns with Batteries

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A battery with a terminal voltage of 12.5 volts is to be trickle-charged at a 0.5 A rate. What resistance should be connected in series with the battery to charge it from a 110-V DC line?
  • 95 ohms.
  • 300 ohms.
  • Correct Answer
    195 ohms.
  • None of these.

A battery with a terminal voltage of 12.5 volts is to be trickle-charged at a 0.5 A rate. What resistance should be connected in series with the battery to charge it from a 110-V DC line?

195 ohms

\[\frac{110V -12.5V}{0.5A} = 195\text{ ohms}\]

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What capacity in amperes does a storage battery need to be in order to operate a 50 watt transmitter for 6 hours? Assume a continuous transmitter load of 70% of the key-locked demand of 40 A, and an emergency light load of 1.5 A.
  • 100 ampere-hours.
  • Correct Answer
    177 ampere-hours.
  • 249 ampere-hours.
  • None of these.

What capacity in amperes does a storage battery need to be in order to operate a 50 watt transmitter for 6 hours?

Assume a continuous transmitter load of 70% of the key-locked demand of 40 A, and an emergency light load of 1.5 A.

177 ampere-hours.

\[40A \times 70\% = 28A\]

\[28A + 1.5A = 29.5A\]

\[29.5 A \times 6 \text{ Hours} = 177 \text{ ampere-hour}s\]

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What is the total voltage when 12 Nickel-Cadmium batteries are connected in series?
  • 12 volts.
  • 12.6 volts.
  • Correct Answer
    15 volts.
  • 72 volts.

What is the total voltage when 12 Nickel-Cadmium batteries are connected in series?

15 volts

The voltage of a single Nickel-Cadmium battery is about 1.2 volts.

When batteries are in series you add the voltage for each cell together (using multiplication since they are all the same) to find the total voltage.

\(1.2V \times 12 = 14.4V\) or about \(15\) volts.

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The average fully-charged voltage of a lead-acid storage cell is:
  • 1 volt.
  • 1.2 volts.
  • 1.56 volts.
  • Correct Answer
    2.06 volts.

The average fully-charged voltage of a lead-acid storage cell is:

2.06

Each lead-acid battery contains 6 cells.
Car batteries hold a little over \(12\) volts, so \[\frac{12.37 V}{6\text{ cells}} = 2.06\text{ volts per cell}\]

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A nickel-cadmium cell has an operating voltage of about:
  • Correct Answer
    1.25 volts.
  • 1.4 volts.
  • 1.5 volts.
  • 2.1 volts.

A nickel-cadmium cell has an operating voltage of about:

1.25 volts.

Please see Wikipedia's article on Nickel–cadmium battery

For overview of the types of battery cells, please see the Battery University article BU-301a: Types of Battery Cells

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