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 DBPR "General Theory and Electrical Principles" section (19–21 items on the Unlimited exam, 13–15 on the Residential exam) reaches past the Code into the hardware: batteries in series and parallel, meters and test instruments, terminations, splices, overloaded and shorted circuits. The arithmetic of series and parallel circuits is in the electrical-theory lesson; 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 battery supplies 5 A for 40 hours.
- **State of
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