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Batteries
14 questions By Tony R. Kuphaldt
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Question 13 of 14
A battery has an advertised capacity of 600 amp-hours, taken from tests performed over an 8-hour period (where capacity in amp-hours = It). According to Peukert’s formula, what rate of current discharge will result in the battery fully discharging in 3 hours (assume an n value of 1.35)?
Reveal answer155 amps
Notes:Ask your students to calculate the amount of current predicted by the “simple” amp-hour equation for a discharge time of 3 hours. In your students’ estimation, which is a more realistic prediction, Peukert’s formula or the amp-hour (It) formula?
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Question 14 of 14
An oft-repeated claim is that lead-acid batteries self-discharge at a greater rate while sitting on a concrete floor, than when installed in an automobile, or on a shelf, or in some other place where there is no direct contact with a concrete surface. Is this claim true, or not?
Design an experiment to test the veracity of this claim, and design it in such a way that a single instance of a defective battery does not skew the results of the test.
Reveal answerThis is a fun topic to discuss! Do your research, and come to discussion time prepared with ideas on how to test this claim.
Notes:I have heard this claim many, many times, but I have not yet been in such a position where I could test it myself. Even if I had tested it, I still wouldn’t give away the answer! There are many practical matters that must be addressed in the setup and testing of batteries for self-discharge. This question provides an excellent opportunity to discuss scientific method with your students, including such principles as double-blind testing, test and control groups, and statistical correlation.
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