What is a Group 66 Battery: Technical Information and Comparison with Alternatives

Group 66 Battery Dimensions

Battery Design

Dimensions and Sizes (Length x Width x Height)
12.0625'' x 7.5625'' x 7.6875'' Inches 306 x 192 x 194 Millimeters

Group 66 Battery Post Terminals

Post Terminal Types and Locations	Posts Used
	Type "A" or manufacturer's custom post design

Group 66 Battery Voltage and Current Characteristics

Volts	Cells	CCA Range
12	6	650-750

Group 66 Alternatives and Closest Battery Groups by Dimensions

There are no direct interchangeable alternatives for group 66 battery if we speak about dimensions, but if your battery space hasn't strict limits, you can choose a little bigger or smaller battery group. If your battery compartment cannot accommodate a larger battery, you can choose a smaller one. In both cases, you must securely fasten your new battery with a battery holder. If your battery holder can't hold the alternative battery group, you can buy a universal battery holder to fit in different types of batteries.

Similar Battery Groups With the Same Length, Width and Voltage

These dimensions will fit you in 99% of cases when you want to use a different battery group instead of a 66 battery since most battery compartments have a height margin and strict limitations on height and width only, which match batteries in the table below. Please check the battery compartment before you buy a battery from this group.

Battery Group Number	Dimensions	Shape	Volts	Cells	Post Terminal Type
Group 66 Battery	12.0625'' x 7.5625'' x 7.6875'' in. 306 x 192 x 194 mm		12	6	"A"
Group 65 Battery	12.0625'' x 7.5625'' x 7.5625'' in. 306 x 192 x 192 mm		12	6	"A"

Closest but not Identical Size Battery Groups

Battery groups in this section below are not identical to the group 66 battery, they can be a little bigger or smaller. Please pay attention to the post terminal types and their location

Closest Groups that Have Slightly Smaller Dimensions

Smaller batteries can have less capacity, performance, and power in comparison with 66 group.

Battery Group Number	Dimensions	Shape	Volts	Cells	Post Terminal Type
Group 66 Battery	12.0625'' x 7.5625'' x 7.6875'' in. 306 x 192 x 194 mm		12	6	"A"
Group 77 Battery	12.0625'' x 7.25'' x 8.75'' in. 306 x 184 x 222 mm		12	6	"A"
Group 79 Battery	12.0625'' x 7.0625'' x 7.375'' in. 307 x 179 x 188 mm		12	6	"S"
Group 27R Battery	12.0625'' x 6.8125'' x 8.875'' in. 306 x 173 x 225 mm Positive post on the Right		12	6	"A", "A2"
Group 27 Battery	12.0625'' x 6.8125'' x 8.875'' in. 306 x 173 x 225 mm		12	6	"A", "A2"
Group 27H Battery	11.75'' x 6.8125'' x 9.25'' in. 298 x 173 x 235 mm		12	6	"A"
Group 41 Battery	11.5625'' x 6.9375'' x 6.9375'' in. 293 x 175 x 175 mm		12	6	"A", "A1"
Group 98R Battery	11.125'' x 6.9375'' x 7.5'' in. 283 x 175 x 190 mm Positive post on the Right		12	6	"A1", "A2"
Group 48 Battery	11'' x 6.9375'' x 7.5'' in. 278 x 175 x 190 mm		12	6	"A", "A1", "A2"
Group 91 Battery	11'' x 6.9375'' x 6.9375'' in. 278 x 175 x 175 mm		12	6	"A1", "A2"
Group 40R Battery	11'' x 6.9375'' x 6.9375'' in. 278 x 175 x 175 mm Positive post on the Right		12	6	"A", "A1"
Group 46 Battery	10.75'' x 6.8125'' x 9'' in. 273 x 173 x 229 mm		12	6	"A", "A1"
Group 24F Battery	10.75'' x 6.8125'' x 9'' in. 273 x 173 x 229 mm		12	6	"A", "A2"

Closest Large Dimensions

Bigger batteries can have more capacity and power compared to 66 batteries.

Battery Group Number	Dimensions	Shape	Volts	Cells	Post Terminal Type
Group 66 Battery	12.0625'' x 7.5625'' x 7.6875'' in. 306 x 192 x 194 mm		12	6	"A"
Group 4DLT Battery	20'' x 8.1875'' x 7.9375'' in. 508 x 208 x 202 mm		12	6	"A"
Group 4D Battery	20.75'' x 8.75'' x 9.8125'' in. 527 x 222 x 250 mm		12	6	"A", "B", "A2"
Group 6D Battery	20.75'' x 10'' x 10.25'' in. 527 x 254 x 260 mm		12	6	"A", "L"
Group 8D Battery	20.75'' x 11.125'' x 9.8125'' in. 527 x 283 x 250 mm		12	6	"A", "A2", "B", "B1"

How to Get 24 Volts from 12V of a 66 Battery Group

If you need 24 Volts, you can connect two group 66 batteries in series to double the voltage. The voltage of a series connection is equal to the sum of the voltages of all its batteries. If one 12V lead-acid battery is connected to another 12V lead-acid battery, you have 24V total power output. Each battery must be fully charged and completely isolated from the other before connecting them in series, or there will be damage to at least one of them.

Increasing a Capacity of 66 Batteries with a Parallel Connection

If you need to increase current capacity and reduce charging time, connect batteries in parallel. When group 66 batteries are in parallel, their voltage is equal to the voltage of one battery, while current capacity equals to the sum of all its battery capacities. If you have two 12V lead-acid batteries with 60 Ah capacity and you connect them in parallel, you'll get 12 Volts with 120 Ah.

Array