Deka Commercial Batteries Explained: Group 31, 4D and 8D

Deka is the battery brand of East Penn Manufacturing, a U.S. manufacturer whose commercial lines are common in tow trucks, service vans, medium-duty fleets and heavy equipment. This guide covers the commercial group sizes operators and fleets ask about most, and how they are ordered through Battery Authority USA.

Group 31: the commercial workhorse

Group 31 is the standard size for medium-duty trucks, commercial vans, many tow trucks, and a lot of equipment. Roughly 13 inches long, it comes in three terminal styles, and getting the terminal right matters as much as the group:

• Stud terminals (31S / 31T): threaded studs for ring terminals, common on trucks and equipment.
• Post terminals (31P / 31A): standard tapered posts.
• Dual terminal: both studs and posts, useful when the fleet has a mix.

Deka's Group 31 comes in flooded versions for starting, AGM versions for vehicles with heavy electrical loads or vibration, and deep-cycle versions for auxiliary power. A tow truck with a lot of lighting and a winch is a good AGM candidate; a plain starting application is fine on flooded.

4D and 8D: heavy trucks and equipment

Group 4D and 8D are the large commercial sizes: 8D is roughly 21 inches long and weighs well over 100 pounds. They are used in heavy trucks, buses, large equipment and marine and RV house banks. Most operators do not carry these on a service truck; they are ordered for pickup or shipping when a fleet or equipment call needs one.

Automotive lines for the rest of the fleet

Deka also covers passenger cars and light trucks across the common groups (24F, 35, 48, 65, 75, 94R) in flooded and AGM. Fleets with a mix of vans and heavy vehicles can standardize on one brand across the whole list.

Reading the label

• Group size sets the physical fit and terminals.
• CCA (cold cranking amps) is the starting power at 0 °F; match or exceed the vehicle's rating, and add margin in cold climates.
• RC (reserve capacity) is how long the battery runs accessories with the engine off; it matters for vehicles that idle with equipment running.
• Date code tells you the battery's age. Sell the oldest first.

Ordering Deka through Battery Authority USA

Battery Authority USA partner and fleet accounts buy Deka (and Continental) at commercial pricing and pick up at partner counters, including East Penn's own branches, which handle warranty on Deka batteries directly. The catalog lists 160+ batteries across both brands; the battery lookup gives the group size and CCA for a specific vehicle; the partner program covers pricing, pickup and the monthly invoice.

Quick reference

Size	Typical use	Carry on the truck?
Group 31	Medium-duty trucks, vans, tow trucks, equipment	Yes, if you run commercial calls
Group 4D	Heavy trucks, buses, equipment	Order for pickup
Group 8D	Heavy trucks, marine and RV banks	Order for pickup or shipping
24F / 35 / 48 / 65 / 75 / 94R	Cars and light trucks	Yes, the common ones