How Automotive Battery Sizes Work

Battery codes look cryptic, but each system encodes physical size, terminal layout and some indication of performance. Importers regularly handle three families of codes in the same order: Japanese Industrial Standard (JIS) codes on Japanese and Korean vehicles, N-series designations common across Asia, Africa and the Middle East, and European DIN/EN codes on European vehicles. American BCI group sizes appear in the Americas. Reading them correctly prevents the two most common battery supply errors: a battery that does not fit the tray, and one whose terminals are on the wrong side.

JIS codes: 55B24L explained

A conventional JIS code has four parts. Using 55B24L as the example:

So 55B24L and 46B24L share the same case, but the 55 is the higher-performance battery. 55B24L and 55B24R have the same size and rating but opposite terminal layouts.

Case group letters

The letter sets the nominal width and height of the case (height excludes terminals). Values below are nominal; actual dimensions vary slightly between manufacturers.

Combined with the length figure, this gives the full footprint. A D31 case is roughly 306 mm long; a G51 case roughly 508 mm long.

Terminal position: L and R

L and R describe which way round the positive and negative terminals sit when the battery is viewed from a defined side. Suppliers' diagrams are not always drawn from the same viewpoint, so confirm against a layout drawing or the battery currently in the vehicle. A reversed layout usually means the cables will not reach, and forcing a connection risks reverse polarity.

Suffixes

Some JIS codes carry an additional (S) after L or R, as in 46B24L(S), often written 46B24LS. In JIS D 5301 it marks the thick (standard-diameter) terminal post on case sizes that can be built with either thin or thick posts; the same code without (S) normally has thin posts. Thin and thick posts are not interchangeable without changing or adapting the cable clamps. See JIS battery size codes explained.

Idling-stop battery codes

Japanese batteries for idling-stop vehicles use a separate code format, such as M-42, N-55, Q-85 or S-95, where the letter indicates case size and the number indicates performance. These letters do not mean the same thing as the case letters in conventional JIS codes. Replace them with a battery rated for idling-stop duty.

N-series designations: N70, N150, NS60

N-series designations are widely used for commercial and replacement batteries across Asia, Africa and the Middle East. In the N-series, the number is broadly aligned with the nominal capacity in ampere-hours: an N70 is around 70 Ah and an N150 around 150 Ah. Exact rated capacity differs between manufacturers, so check the label.

• NS denotes a smaller case (for example NS40, NS60, NS70), used in passenger cars. The number does not map to Ah as directly as in the N range.
• Z after the number (for example N70Z) usually indicates a higher-rated variant of the base battery; in GS Yuasa's data N50Z and N70Z use the same case sizes as N50 and N70.
• L after the designation (for example NS60L) indicates the reversed terminal layout.

N-series batteries are often supplied in case sizes that correspond to JIS groups. Typical correspondence:

Treat this as a starting point only. Confirm the length, width, total height and terminal layout of the specific battery.

DIN and EN codes

European batteries are identified by a DIN code or an ETN (European Type Number). They are also grouped by standard case sizes.

DIN five-digit code

In a code such as 57412:

• The first digit indicates the capacity band: 5 for below 100 Ah, 6 for 100–199 Ah, 7 for 200 Ah and above.
• The next two digits give the capacity within that band: 74 Ah in this example. For a code starting with 6, add 100.
• The last two digits identify the type variant within that capacity, covering terminal layout, hold-down style and other features.

ETN nine-digit code

An ETN such as 574 012 068 has three groups: the first three digits are the capacity code as above, the middle three identify the type, and the last three give cold cranking current divided by ten. So 068 indicates 680 A under the EN test method.

Case sizes

European passenger batteries use standard case sizes such as L2, L3, L4 and L5, which share width and height but differ in length. Low-base versions (LB) are lower in height. European cases usually have a bottom hold-down ledge along the long sides, so the clamp design matters as well as the dimensions.

The difference between JIS and DIN batteries in terminal posts, hold-downs and heights is covered in JIS vs DIN automotive batteries.

BCI group sizes

In North America and parts of Latin America, batteries are identified by BCI group numbers such as 24, 27, 31, 34 or 65. The group defines case dimensions and terminal layout. The group number carries no performance rating, so specify CCA and reserve capacity separately.

What a code does not tell you

A size code is a fit specification. It does not fully define:

• Technology: flooded, EFB or AGM. See EFB vs AGM batteries.
• Cold cranking current under a specific test standard (JIS, EN and SAE tests produce different figures for the same battery)
• Reserve capacity and cycling performance
• Construction: maintenance-free, low-maintenance or dry-charged
• Terminal type: taper posts, thin posts, or threaded studs on some commercial batteries

Specifying batteries on an order

For each line include the code, terminal layout, technology, the minimum CCA and the test standard it refers to, and whether the batteries should be supplied filled or dry-charged. Browse automotive batteries, pickup and SUV batteries and truck and bus batteries, or send a mixed battery list through the RFQ upload.