Editorial Technical Reference

Battery terminal post

Battery terminal posts for lead-acid batteries and lithium-ion cells · tapered automotive (SAE-type) posts, stud, threaded-insert and flag terminals, tightening torque, lead-alloy terminals with sealing rings, aluminium and copper cell terminals, busbar plating and contact resistance

A battery terminal post is the conductive pole that carries current between the cells inside a battery or cell case and the external circuit, and gives a cable clamp, lug or busbar a fixed point to bolt or clamp to. On lead-acid batteries it is a lead-alloy post or bushing sealed into the lid; on lithium-ion cells it is an aluminium or copper terminal on the cell cover. Ask three things first: the post type and dimensions your clamp or busbar must fit, the tightening torque and thread, and the material, sealing and plating that will keep contact resistance low.

Terminal posts and bushings for lead-acid batteries (tapered automotive posts, stud, threaded-insert and flag or bolt terminals) and output terminals of lithium-ion cells, including their bolted busbar interface. Cable clamps and ring lugs, busbars, connectors, battery cables and terminal protection sprays are outside this page except where compared.

CNFX editorial research · Sources checked October 11, 2026 · 5 sources

Identify post type, size and torque Check material, sealing and contact

Silver-grey metal terminal post with a smooth cylindrical top, grooved rings around the neck and a wider flanged base, clamped between steel blocks in a machining fixture — Terminal post held in a fixture

Start with your task

Identify post type, size and torquemm, taper, N·m. Check material, sealing and contactLead, aluminium, plating, µΩ.

Identify the post type, size and torque

Discover's terminal specification sheet (dimensions in millimetres) lists its SAE-type tapered post with dimension A of 19.5 mm for the positive and 17.9 mm for the negative, a 1:9 taper, a 20 mm height (D) and a tightening torque of 8 N·m (6 ft-lbs). Its AM terminal pairs that post with a 5/16" stud at 13 N·m, and its AT terminal with a 3/8" stud at 14 N·m. The same sheet shows an M10 threaded insert (Pz) and an M10 traction (PM) terminal, and nut-and-bolt and insert (flag) terminal types with torques from 4 to 16 N·m. [1]

Editorial calculation: in Discover's table the positive post is 19.5 − 17.9 = 1.6 mm larger than the negative in dimension A, so a clamp sized for the positive post will not seat correctly on the negative. [1]

Editorial note: torque belongs to the terminal type, not the battery, so the order should name the terminal code and the torque the battery maker states for it.

Give the supplier the battery type (lead-acid flooded, AGM, gel, lithium-ion cell or module), the terminal type and code, post or stud dimensions and taper, thread size and depth, tightening torque, the clamp, lug or busbar it must fit, continuous and peak current, material and plating, sealing method in the lid, operating temperature, any corrosion test required, drawings and quantity.

Check material, sealing and contact resistance

A Water Gremlin patent describes lead-acid battery terminals made from lead alloy with annular rings around the head, embedded in the container wall to prevent electrolyte leakage. It notes that hot forming (casting molten lead alloy) may create porosity in the terminal, and describes cold forming the rings with undercuts to improve sealing. [3] An earlier Water Gremlin patent describes a cold-formed lead terminal with torque-lock recesses that mate with the thermoplastic container so the terminal resists turning and does not come loose. [4]

For lithium-ion cells, a patent on aluminium-cased accumulators states that the container, cover and positive output terminal are made from grade 1050 aluminium (99.5% aluminium) for weld compatibility, that the negative current collector is made of copper, nickel-coated copper or aluminium, and that cells are joined into packs by aluminium or copper busbars. Its claimed terminal alloy contains 0.01–4% magnesium and 0.05–0.3% copper with a breaking strength (Rm) of at least 60 MPa. [5]

A study of bolted copper–aluminium busbar connections in lithium-ion battery systems used M6 bolts at 8 N·m (and 4, 8 and 12 N·m in the contact-force test), copper busbars tin-plated over a 5 or 8 µm nickel underlayer or tin-plated at 6 µm, and test currents of 100, 200 and 300 A. Contact resistance of nickel-plated aluminium stayed at about 15 µΩ, while bare aluminium rose to 400–750 µΩ, which the authors attribute to oxide growth on the aluminium surface. [2]

Editorial calculation: heat at a contact is I² × R, so at 300 A a 15 µΩ joint dissipates about 300² × 0.000015 ≈ 1.4 W, and a 750 µΩ joint about 300² × 0.00075 ≈ 68 W. [2]

Drawing, alloy, plating and leak tests to request from terminal makers

When requesting quotations, ask each supplier for the terminal drawing with tolerances, the alloy or material grade, plating type and thickness, the torque rating, sealing design and test reports for leakage, contact resistance and corrosion.

From post to busbar joint, part by part

Element	Role	Fix in the order
Post or stud	Takes the clamp, lug or nut. [1]	Type, size, taper, thread.
Head with annular rings	Seals the terminal in the lid. [3]	Ring design, forming method.
Torque locks	Stop the terminal turning in the container. [4]	Lock design.
Cell terminal	Aluminium or copper pole on the cell cover. [5]	Alloy, weld or bolt joint.
Busbar interface	Bolted copper–aluminium contact. [2]	Plating, bolt, torque.

Published values for thread, torque, material and contact resistance

Torque and thread come from Discover's sheet, material from the patents and contact resistance from the busbar study; temperature range, hardness and weight are left for the terminal maker's drawing.

Field	What it means and published values	Ask the supplier for
Thread Size	5/16" and 3/8" studs; M10 insert; M6 busbar bolts. [1] [2]	Thread and depth.
Current Rating	Not stated for a terminal; tests at 100–300 A on bolted busbars. [2]	Continuous and peak A.
Electrical Resistance	About 15 µΩ nickel-plated vs 400–750 µΩ bare aluminium contacts. [2]	Contact resistance and method.
Temperature Range	Not stated in reviewed sources.	Operating range.
Torque Rating	8 N·m SAE-type post; 13–14 N·m stud types; 4–16 N·m flag types. [1]	Torque per terminal code.
Corrosion Resistance	Oxide growth on bare aluminium raised resistance. [2]	Test standard and hours.
Material	Lead alloy (lead-acid); grade 1050 aluminium, copper (Li-ion). [3] [5]	Alloy grade.
Plating Thickness	Tin over 5 or 8 µm nickel; tin 6 µm on copper busbars. [2]	Plating and thickness.
Tensile Strength	Rm ≥ 60 MPa for one claimed aluminium terminal alloy. [5]	Rm of the grade.
Hardness	Not stated in reviewed sources.	Hardness and temper.
Weight	Not stated in reviewed sources.	Mass per terminal.

Send the battery, terminal and connection data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Battery: [lead-acid type or Li-ion cell/module]
Terminal: [type/code; dimensions; taper; thread]
Connection: [clamp, lug or busbar; torque]
Current: [continuous A; peak A]
Material: [alloy; plating; thickness]
Sealing and tests: [leakage; resistance; corrosion]
Quantity: [pieces]

See manufacturer records Send an enquiry through CNFX

Buyer questions

Are positive and negative battery posts the same size?

No. Discover lists its SAE-type post at 19.5 mm positive and 17.9 mm negative, both with a 1:9 taper. [1]

What torque should a battery terminal take?

It depends on the terminal: Discover lists 8 N·m for its SAE-type post and 13–14 N·m for its stud terminals. [1]

Why plate aluminium terminals and busbars?

In one study, nickel-plated aluminium contacts held about 15 µΩ, while bare aluminium rose to 400–750 µΩ from oxide growth. [2]

Sources and what still needs a direct check

Sources checked 2026-10-11. One source is a battery maker's terminal specification sheet, one is an open-access study of busbar contact resistance, and three are patents describing terminal design and materials. Values for your terminal must come from the supplier's drawing and tests.

Still to check yourself

Name the terminal type and code.
Match post size and taper to the clamp.
Confirm torque per terminal.
Check alloy, plating and sealing.
Verify the legal supplier and factory.