Group 48 (H6, L3, 66L3) Batteries - Dimensions, Features, and Recommendations

Group 48 (H6, L3, 66L3) batteries are mid-range batteries commonly used as automotive, marine, and light industrial batteries, as starting or dual-purpose batteries, and for powering various electric and electronic devices while the main engine(s) are turned off or while the mains power is not present.

Most BCI Group 48 (H6, L3, 66L3) batteries are designed as maintenance-free, spill-proof AGM batteries with increased resistance to vibrations and mechanical shocks (when compared with the older wet/flooded lead-acid batteries).

Updated: June 23, 2023.

Group 48/H6 Battery Dimensions and Specifications

Standard BCI Group 48 batteries feature dimensions of (L x W x H) 11 x 6 7/8 x 7 1/2 inches (11 x 6.875 x 7.5625 inches, ~278 x 175 x 190 mm) and are similar to the standard DIN H6 battery (also labeled as L3 battery) and EN 66L3 battery that feature physical dimensions of (L x W x H) of 278 x 175 x 190 mm.

Generally, batteries labeled as H6 or L3 batteries (DIN standard) EN 66L3 (EN standard) are considered BCI Group 48 equivalent batteries, and vice versa due to the similarities in size.

However, BCI Group 98R have physical dimensions very close to the H6, L3, or 66L3 batteries:

• BCI Group 48: 278 x 175 x 190 mm,
• H6, L3, 66L3: 278 x 175 x 190 mm,
• BCI Group 98R: 283 x 175 x 190 mm.

That is the reason why BCI Group 98R is also sometimes considered as H6, L3, 66L3 battery equivalent battery, despite being ~5 mm longer.

The positive terminal of the group 48 batteries is on the right side of the battery when the battery is placed in front of the user.

The list of most popular BCI Group 48/H6 batteries is given in the following comparison chart:

Note: Amazon affiliate links ('Model' column) open in the new windows; feel free to check them for the most up-to-date offers and prices.

On average, Group 48 batteries feature a nominal capacity of 60 to 72 Ah, CCA rating of 720-800 Amps, MCA rating of 800-930 Amps, RC value of 120-140 minutes, and they weigh 45 - 54 pounds (20 - 24 kg).

Group 48 batteries are mostly AGM starting or dual-purpose batteries, but lithium group 48 batteries, in the form of Lithium Iron Phosphate (LiFePO₄) batteries, are slowly emerging on the market.

Note: For lithium batteries to be safe, they must feature a complete Battery Management System (BMS), which protects the battery from unwanted events like overcharging, over-discharging, low and high temperatures, and similar.

Starting AGM Group 48 batteries are somewhat lighter than dual-purpose batteries due to the thinner lead plates. They are not intended for deep discharge cycle applications - they are used in cars and other vehicles as starting batteries and are designed to accept charge quickly to withstand high-demanding 'Stop&Go' applications.

Note: not all starting AGM Group 48 batteries are suitable for 'Stop&Go' applications.

High-end dual-purpose group 48 batteries (like Optima DH6 YellowTop - Amazon link, opens in the new window) are versatile batteries that can provide large starting currents but are also robust enough to withstand deep discharge applications.

Optima DH6 YellowTop is one of the heaviest group 48/H6 batteries, but it also has the highest nominal capacity and best CCA, MCA, and RC values, even when compared with lithium group 48 batteries.

As such, dual-purpose group 48/H6 batteries are suitable for a broad range of applications, including starting/cranking applications, trolling motor batteries, sump pump backup batteries, medical and security systems, various off-the-grid applications, and similar.

Note: XS Power D4800 battery features a declared MCA rating of 815 Amps, but this is general purpose battery, more suitable for industrial applications and to power, for example, high-end car multi-media systems in dual-battery electric installations - it can crank small to medium gas and diesel engines, but not as well as NorthStar, Odyssey or Optima group 48 battery. IMHO, of course.

How to Charge Group 48/H6 Battery?

If the group 48/H6 battery is connected to an electric system that features a battery charger, let the built-in battery charger charge the battery. For example, when connected to the car's electric system, let the alternator (combined with some control electronics) charge the battery.

When these batteries are charged separately, it is highly recommended to use an intelligent AGM battery charger that first analyses the battery and then adjusts the charging process according to the battery condition and the local temperature (temperature compensation).

When the 70 Ah battery is discharged down to 50% DoD, 10 Amps battery charger needs ~4 hours to charge it fully - testing/analysis, desulphation, and equalization charging phases are (mostly) included in these 4 hours.

And when the battery is fully charged, the intelligent AGM battery charger switches to the maintenance charging mode, monitoring the battery and keeping it fully charged.

15 Amps battery chargers may do this task even faster, but too strong charging currents may shorten the operating lifetime of the battery.

So, check the maximum and recommended charging current of your battery (regardless of the battery group) and charge according to the manufacturer's recommendations - 10 Amps charging currents for Group 48/H6 batteries should not be a problem, even when the battery is used in deep cycle applications.

Long Story Short: if you are looking for a new group 48/H6 lead-acid battery, go for a good AGM (Absorbent Glass Mat) SLA (Sealed Lead Acid) battery from a reputable brand.

When ordering, just be sure to check the battery nominal capacity, battery's CCA, MCA, and RC ratings, terminal types, orientation (positive should be on the right, but just in case ...), base hold-down type, etc.

Group 48 AGM batteries and group H6 AGM batteries are rather popular in passenger cars, SUVs, trucks, and other vehicles, in marine applications and light industrial applications and the users should have problems finding suitable group 48/H6 batteries.