Batteries in Series and Parallel, Meters and Test Instruments, and Splices and Terminations
Theory from NEETS Module 1 (NAVEDTRA 14173A) chapter 2 and Module 3 (NAVEDTRA 14175A) chapters 1 and 3, read 2026-09-20 (read-log-neets.md); NFPA 70-2023 110.14 and 110.11 as read in read-log-2023.md · Reviewed 2026-09-21
The PSI "Maintain Basic Electrical Circuits" block (21 items Class I — the largest single block for the Class I candidate — and 14 for Class II) is a maintenance list: connect batteries in series and parallel, check and replace meters, check terminations, make splices and repairs, find overloaded and shorted circuits. The arithmetic of series and parallel circuits is in lesson nec-01-03; this lesson is the hardware. Theory paraphrases the public-domain Navy NEETS course; termination and splice rules are NEC 110.14.
1. Cells and batteries (NEETS Module 1, 2.3–2.4)
- Primary cells (dry cells, alkaline) are used up and replaced; secondary cells are recharged. The lead-acid cell — lead peroxide positive plate, sponge-lead negative plate, sulfuric-acid electrolyte — is the most widely used secondary cell (about 2 volts per cell; a 12-V battery is six cells). Nickel-cadmium cells (potassium-hydroxide electrolyte) charge faster, hold charge in storage and survive many cycles; silver-zinc and silver-cadmium cells are the light, expensive emergency types.
- Series connection: negative of one cell to positive of the next; the end terminals feed the load. Voltage adds, current capacity stays that of one cell — four 1.5-V cells in series give 6 V at the single-cell ampere rating. Never join the two free end terminals: that is a dead short across the whole battery.
- Parallel connection: all positives to one line, all negatives to the other. Voltage stays at one cell, current capacity adds — four ⅛-A cells in parallel supply ½ A at 1.5 V. Parallel only identical cells at the same state of charge, or the stronger cell discharges into the weaker.
- Series-parallel: series strings for the voltage, strings in parallel for the current — e.g. four strings of three 1.5-V cells = 4.5 V at four times one cell's current.
- Capacity is rated in ampere-hours (amperes × hours), normally at the 20-hour rate (a battery that delivers 20 A for 20 h is a 400-Ah battery). Capacity falls as the discharge rate rises: the 400-Ah battery gives 400 A for less than an hour. A 200-Ah batter
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