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Batteries
14 questions By Tony R. Kuphaldt
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Question 1 of 14
If I wanted to build a battery-powered electric drill, would it be better to use primary cell batteries, or secondary cell batteries? Explain your answer.
Reveal answer“Secondary” cell batteries would be better to use for an application such as an electric drill, because it would be wasteful to have to discard so many primary-cell batteries at the rate they would be “consumed” powering such a device.
Notes:Basically, the point of this question is to get students to research what the difference is between a primary and a secondary cell. Framing the question in a practical context makes it more interesting, and involves other practical issues as well (economics, conservation, etc.).
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Question 2 of 14
Identify some common “primary” cell types, as well as some common “secondary” cell types. For each of these battery types, identify their standard output voltages.
Reveal answerPrimary cell types and voltages:
- • Carbon-zinc: 1.5 volts
- • Alkaline: 1.5 volts
- • Lithium: 1.8 to 3.65 volts, depending on exact chemical makeup
- • Mercuric-oxide: 1.35 to 1.4 volts
Secondary cell types and voltages:
- • Lead-acid: 2.1 volts
- • Nickel-cadmium: 1.2 volts
- • Silver-zinc: 1.5 volts
Follow-up question: what are some of the safety and environmental concerns regarding the chemical substances used in batteries, both primary and secondary types?
Notes:Challenge your students to list a few cell types other than what is listed in the answer section.
Note: data for typical cell output voltages taken from chapter 20 of the Electronic Engineer’s Reference Book, 5th edition (edited by F. Mazda).
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Question 3 of 14
Batteries store energy in the form of chemical bonds between atoms. When a complete circuit is connected to the terminals of a battery, a current begins inside the battery and through the circuit. Chemical reactions begin inside the battery at the same time the circuit is formed, fueling this current. When all the chemicals have been depleted, though, the current will cease. This is what happens when a battery “dies.”
Explain what takes place when a battery is recharged, and what electrical device(s) must be connected to a battery to recharge it. Be as specific as possible in your answer.
Reveal answerRecharging is a reversal of the chemical reactions taking place during the discharge of a battery. In order for this to occur, some external source of energy must force current backward through the battery.
Notes:It is important to note to your students that not all battery types lend themselves to recharging, even though many “primary” cells can be rejuvenated a small degree by being put through a charging (reverse-current) cycle.
sometimes battery with small capacity (Ah) has a high Cranking Amperes (CA). for example Motorcycle battery 4 Ah has 140 CA. Automotive battery 35 Ah has 350 CA. 35 Ah is more than 8 times of 4 Ah but the CA just only 350 CA