Chapter 1-5 Review: Batteries, Cells, Amp Hours, and Basic Circuits

Flashcards covering key concepts from Chapter 1 through Chapter 5: circuit basics, battery vs cell, redox chemistry, amp-hours and energy calculations, series/parallel battery configurations, reliability under load, memory effects, and lead-acid and lithium chemistries.

What is the maximum current in the described solar circuit, and how is it calculated?

53 mA; calculated using I = V/R with V ≈ 6.95 V across R = 130 Ω (6.95/130 ≈ 0.053 A).

In a simple series circuit, how is current related to the components and what is the basic formula?

The same current flows through all components; I = Vtotal / Rtotal (current is set by the supply and the total resistance).

What is the difference between a battery and a cell?

A battery is made of multiple cells; a cell is a single electrochemical unit with electrolyte and two dissimilar metals that provides voltage.

What voltages are typical for NiMH AA cells versus alkaline AA cells, and how are they related to the ‘true battery’ concept?

NiMH AA cells are about 1.2 V; alkaline AA cells are about 1.5 V; a 9-volt battery is a true battery comprised of multiple cells in series.

What is a salt bridge in a Daniell cell, and why is it needed?

A salt bridge connects the two half-cells to allow ion flow, maintaining charge balance as electrons move from zinc (anode) to copper (cathode).

In a copper–zinc Daniell cell, which electrode undergoes oxidation and what happens to the electrons?

Zinc oxidizes at the anode, releasing electrons that flow through the external circuit to the copper cathode where reduction occurs.

Why is the Daniell cell’s voltage about 1.1 V, and how do half-cell potentials explain this?

The cell voltage equals Ecathode − Eanode; Cu has a higher reduction potential than Zn, giving a difference of about 1.1 V (Cu around +0.34 V, Zn around −0.76 V).

What is the per-cell voltage typical for lithium cells compared to a Cu–Zn Daniell cell?

Lithium cells are about 3.3–3.5 V per cell, which is higher than the ~1.1 V per Cu–Zn Daniell cell.

Does battery size determine its voltage?

No. Voltage is determined by the chemistry and the number of series-connected cells; a smaller battery can have higher voltage than a larger one (e.g., 9 V vs D cell).

What is an amp-hour (Ah), and how many coulombs are in 1 Ah?

Amp-hour is a measure of charge capacity; 1 Ah = 3600 coulombs.

How do you convert amp-hours to coulombs, and how is energy in joules calculated from Ah and voltage?

Q (C) = Ah × 3600; Energy E (J) = Q × V = (Ah × 3600) × V.

What is a watt-hour, and how is it calculated?

Watt-hours = Voltage × Amp-hours; e.g., 3.7 V × 1.5 Ah = 5.55 Wh.

What happens to a battery’s voltage and capacity when cells are connected in series vs in parallel?

Series: voltages add, capacity (Ah) stays the same; Parallel: capacity (Ah) increases, current capability increases, voltage stays the same.

What happens if one cell in a series chain is weak?

The overall output degrades; increased series resistance and reduced current capability; the chain is limited by the weakest cell.

Why test a battery under load rather than unloaded?

Unloaded batteries can look good, but under load their true performance and discharge rate are revealed.

What is the memory effect, and which battery types are associated with it?

Memory effect is the apparent loss of capacity due to partial charging cycles; strongly associated with NiCd (NiCad) and to a lesser extent NiMH.

What are the typical per-cell voltage and total voltage for a lead-acid battery, and how many cells are in a 12 V lead-acid pack?

Lead-acid cells are about 2.0 V each; a 12 V lead-acid battery typically has six cells (2.0 V × 6 ≈ 12 V).

What is the typical charging voltage range for a car battery?

Approximately 13–14 V when charging.

In a discharging battery, where is the current emitted from, and what is the role of the cathode?

Current leaves the battery at the cathode (positive terminal) in a discharging cell; the anode is where electrons originate.

What is a sacrificial anode, and why is it used in marine environments?

A sacrificial anode is a metal that corrodes preferentially to protect more valuable metal structures in an electrolyte, commonly used on ships to prevent galvanic corrosion of steel or copper components.

How do you relate charge, voltage, and energy for the example with a 1.5 V cell and 2.85 Ah rating to obtain joules?

Q = 2.85 Ah × 3600 = 10,260 C; E = Q × V = 10,260 C × 1.5 V = 15,390 J.