• 14 parts
  • Checked September 2026

Parts of a Car Battery

A 12-volt battery cut open, then one terminal from above.

Parts of a Car Battery

Name Date

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1 2 3 4 5 6 7 8 9 10 11 12 13 14
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Write the name of each numbered part.Answer key

  1. Case
  2. Cover
  3. Vent plugs
  4. Positive terminal (+)
  5. Negative terminal (-)
  6. Cell
  7. Plates
  8. Separators
  9. Electrolyte
  10. Hold-down clamp
  11. Terminal post
  12. Terminal clamp
  13. Clamp bolt
  14. Battery cable

Drawn for this site on 2026-09-30 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: the spark plug the battery helps fire

All 14 parts on the diagram

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Outside the battery 6

  1. Case The box that holds the cells. It is divided inside into a compartment for each cell.
  2. Cover The lid sealed on top of the case. The two posts and the vent plugs come through it.
  3. Vent plugs One for each cell. They let gas escape and keep the electrolyte in. A sealed battery has none to open.
  4. Positive terminal (+) The post marked +. It is slightly larger than the negative one, so the cables cannot be swapped by mistake.
  5. Negative terminal (-) The post marked -. Its cable is taken off first and put back last.
  6. Hold-down clamp Holds the battery on its tray so it cannot move about.

Inside a cell 4

  1. Cell One of six compartments, each a small battery of about 2 volts. Joined in a row they make a 12-volt battery.
  2. Plates Flat lead plates, positive and negative in turn. The chemical action between them and the electrolyte makes the current.
  3. Separators Thin porous sheets between the plates. They keep the plates from touching and let the electrolyte flow through.
  4. Electrolyte A mixture of sulfuric acid and water that covers the plates.

The terminal 4

  1. Terminal post The round lead post on the battery. It is shaped as a cone with its top cut off, a little narrower at the top.
  2. Terminal clamp The clamp on the end of the cable. It fits round the post and is split, so the bolt can pull it tight.
  3. Clamp bolt A bolt and nut through the two ears of the clamp. Tightening it squeezes the clamp onto the post.
  4. Battery cable The thick cable carrying the current between the battery and the car.

How this list was compiled: Read 2026-09-30; a name is kept only where at least two of these use it. (1) US Army, TM 9-8000, Principles of Automotive Vehicles (1985, public domain), chapter 12, Batteries: cells of 2 volts, six in series for 12 volts; positive and negative plates, separators, electrolyte of sulfuric acid and water, container with a compartment for each cell, cover with openings for the two battery posts and a vent plug for each cell; https://archive.org/details/tm-9-8000-principles-of-automotive-vehicles-1985 . (2) US Army, TM 9-6140-200-14, Maintenance Manual for Lead-Acid Storage Batteries (1998): terminal posts, terminal clamps and cable clamps, clamp nuts and bolts, battery cables, vent caps, battery case and cover, hold-downs, the positive post larger than the negative, the negative clamp taken off first; https://archive.org/details/tm-9-6140-200-14-maintenance-manual-for-lead-acid-storage-batteries-1998 . (3) A 2009 Toyota Avalon owner's manual, for naming only: terminals, hold-down clamp, terminal clamp bolts; https://archive.org/details/toyota-avalon-02009-owners-manual . (4) Wikipedia, text only: Automotive battery (six cells, nominal 12 volts), Battery terminal (lead posts shaped as truncated cones, of slightly different diameters), Lead-acid battery (plates, separators, electrolyte). Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's battery, nothing traced. Licence: own work

How it works

A 12-volt car battery with its front wall cut away, one cell enlarged, then one terminal from above with its cable clamp. Tap a part to read what it does.

Read the full guide

Inside the battery

A car battery is six cells in one case. In each cell, positive and negative lead plates stand in electrolyte, with a separator between every two plates so they cannot touch. The cover seals the top, and a post at each end carries the current out.

Parts of a car battery terminal

The last view shows one terminal from above. The terminal clamp on the end of the battery cable fits round the terminal post, and the clamp bolt squeezes it tight.

  • Corrosion on a terminal resists the flow of current to the starter, so keep both terminals clean and their clamps tight.

Questions and answers

What are the parts of a car battery terminal?

The terminal post on the battery, the terminal clamp that fits round it, the clamp bolt and nut that tighten the clamp, and the battery cable fixed to the clamp.

Which battery terminal is positive?

The one marked + on the cover. On a battery with posts on top, the positive post is also slightly larger than the negative one, so each clamp fits only its own post.

What is inside a car battery?

Six cells. Each holds positive and negative lead plates with thin separators between them, covered by electrolyte, which is a mixture of sulfuric acid and water.

How many cells are in a car battery?

Six. Each cell gives about 2 volts, and the six are joined in series to make a 12-volt battery.

Which battery cable do you take off first?

The negative one. The negative cable comes off first and goes back on last.

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