Group 41 (T65, 54LB) Batteries - Dimensions, Features, and Equivalents

Group 41 (T65, 54LB) batteries are a type of automotive starting, lighting, and ignition (SLI) battery. These batteries are designed to deliver a high starting current to crank the engine and recharge quickly.

Also, Group 41 batteries are used in light industrial and marine applications where 600-650 CCA batteries are required.

Published: June 28, 2023.

Group 41 (T65, 54LB) Batteries Features and Specifications

The dimensions of a battery are a critical factor, as the battery must fit appropriately within the vehicle's battery tray and compartment.

The Group 41 battery physical dimensions are (L x W x H) 11 9/16 x 6 15/16 x 6 15/16 inches (11.5625 x 6.9375 x 6.9375 inches, 293 x 175 x 175 mm) and they weigh ~36-38 pounds (~16.3 - 17.2 kg).

As starting batteries, Group 41 batteries feature CCA (Cold Cranking Amps) ratings of around 650-675 Amps and MCA/CA (Marine Cranking Amps/Cranking Amps) ratings of around 800-835 Amps, which is enough to crank most gasoline and diesel small to medium car engines.

Group 41 batteries also feature a Reserve Capacity (RC) of around 100-115 minutes and, in theory, can be used as dual-purpose batteries, but they are very rarely designed for such purpose - they are almost exclusively designed as starting/cranking batteries.

Group 41 batteries are sometimes also labeled as T65 and/or 54LB batteries - the T65 label is DIN Code, and the 54LB label is EN Code for car batteries with physical dimensions of 293 x 175 x 175 mm - the exact dimensions of Group 41 battery.

The following comparison chart lists some of the Group 41 batteries with their most important features and specifications:

As one can see, Group 41 (T65, 54LB) batteries are practically all starting, lead-acid, flooded batteries - some of them are "Enhanced Flooded" lead-acid batteries. They are maintenance-free batteries (but they still have to be mounted in a vertical position).

However, most of them are "classic" lead-acid, flooded batteries that must be regularly maintained, especially during hot summer days (add distilled water to cells, clean corrosion from battery terminals, etc.).

 Group 41 (T65, 54LB) Equivalent Batteries

Group 41 batteries can be found at local hardware stores, car repair shops, and online stores.

However, if they are not available, one can look for a few similar batteries that may differ in size, battery terminal, hold-downs, and a few more details. These batteries include:

• Group 41 (T65, 54LB): 11 9/16 x 6 15/16 x 6 15/16 inches, 293 x 175 x 175 mm, reference battery,
• Group 40R (T6, LB3, 66LB): 10 15/16 x 6 7/8 x 6 7/8 inches, 277 x 175 x 175 mm - somewhat smaller; check the battery terminal orientation,
• Group 48 (H6, L3, 66L3): 11 x 6 7/8 x 7 1/2 inches, 278 x 175 x 190 mm, somewhat shorter, but also taller battery,
• Group 91 (T6, LB3, 66LB): 11 x 6 7/8 x 6 7/8 inches, 280 x 175 x 175 mm, somewhat smaller,
• Group 92 (T7, LB4, 77LB): 12 7/16 x 6 7/8 x 6 7/8 inches, 316 x 175 x 175 mm, somewhat longer.

Obviously, there are batteries that are similar to Group 41 batteries, but one should always try to get exactly the same battery size for a new battery. Better safe than sorry.

How To Charge Group 41 Battery

When the battery is connected to the car's electric system, let the car keep the battery fully charged.

However, when the battery is charged on the workbench, one should use an advanced lead-acid battery charger, set it to "Flooded Battery," and use a temperature probe/sensor to allow the battery charger to compensate for the charging temperature.

Although Group 41 batteries are designed to accept the charge fast, if they are charged on the bench, it is recommended to use charging currents in the 5-8 Amps range (depending on the battery model).

Such battery chargers should also feature advanced charging modes, including cell equalization, desulfation, maintenance mode, and similar.

For example, suppose the 50Ah battery is discharged down to 80% DoD. In that case, it requires ~40Ah charge to charge it to 100% SoC - 5 Amps battery charger can recharge such battery in 8.5-10h, depending on the battery condition and the exact charging requirements (desulfation, equalization, etc.).

But, again, Group 41 batteries are starting/cranking batteries, and if you have to charge them often using a battery charger, check the electric system of your car - start with the alternator and charging controller, but also check parasite drain, just in case...

Long Story Short: Group 41 batteries are used as automotive and marine starting batteries and as high-current batteries in light-industrial applications.

Most Group 41 batteries are flooded, lead-acid batteries - AGM lead-acid and lithium Group 41 batteries are very rare, and if you need such batteries, consider batteries from other similar battery groups; just be sure to pay attention to the exact battery size, battery terminal type, and orientation, battery hold-downs, chemistry, etc.