The Best Car Battery - Brands, Types, Features, and Specifications

Choosing 'the best' car battery can be somewhat confusing, since just like cars, car batteries come in various sizes, shapes and also differ in terminal types and orientation, exact chemistry, CCA/MCA features, battery type, etc.

Picking the right battery means having the battery that will do its job for years to come, without leaving the user stranded with the dead car battery when needed the most.

On This Page:

optima 8002 002 34- Battery Types, Features, and Specifications

- Top 10 Most Popular Car Battery Sizes

- BCI Group 24 Batteries

- BCI Group 34/78 Batteries

- BCI Group 35 Batteries

- BCI Group 47 (H5, L2, 55L2) Batteries

- BCI Group 48 (H6, L3, 66L3) Batteries

- BCI Group 49 (H8, L5, 88L5) Batteries

- BCI Group 51 and 51R Batteries

- BCI Group 65 Batteries

- BCI Group 75 Batteries

- BCI Group 94R Batteries 

- Other Battery Groups

- How to Charge the Car Battery  


Battery Types, Features, and Specifications

When looking for a new car battery, there are few things to consider:

- Battery Sizes are defined by BCI Battery Groups, EN codes, and DIN codes. Although the batteries are usually manufactured to the exact battery size standards, it is highly recommended to measure the battery compartment in the car and to check actual battery dimensions before making a purchase - just to be sure.

The following cross-reference chart lists some of the most popular BCI Battery Groups, with their equivalent EN and DIN codes:

Maximum BCI Battery Dimensions
(L x W x H, inch/mm)
BCI Group Maximum DIN/EN Battery Dimensions
(L x W x H mm)
DIN Codes EN Codes
10 15/16 x 6 7/8 x 6 7/8
277 x 175 x 175
40R 278 x 175 x 175 T6, LB3 66LB
11 3/16 x 6 7/8 x 6 7/8
293 x 175 x 175
41 293 x 175 x 175 T65 54LB
9 5/16 x 6 13/16 x 6 13/16
243 x 173 x 173
42 242 x 175 x 175 T5, LB2 45LB
9 11/16 x 6 7/8 x 7 1/2
246 x 175 x 190
47 242 x 175 x 190 H5, L2 55L2
12 1/16 x 6 7/8 x 7 9/16
306 x 175 x 192
48 278 x 175 x 190 H6, L3 66L3
15 x 6 7/8 x 7 3/16
381 x 175 x 192
49 354 x 175 x 190 H8, L5 88L5
9 11/16 x 6 7/8 x 6 7/8
246 x 175 x 175
90 242 x 175 x 175 T5, LB2 45LB
11 x 6 7/8 x 6 7/8
280 x 175 x 175
91 278 x 175 x 175 T6, LB3 66LB
12 1/2 x 6 7/8 x 6 7/8
317 x 175 x 175
92 315 x 175 x 175 T7, LB4 77LB
15 x 6 7/8 x 6 7/8
354 x 175 x 175
93 354 x 175 x 175 T8, LB5 88LB
12 3/8 x 6 7/8 x 7 1/2
315 x 175 x 190
94R 315 x 175 x 190 H7, L4 77L4
15 9/16 x 6 7/8 x 7 1/2
394 x 175 x 190
95R 394 x 175 x 190 H9, L6 -
9 15/16 x 6 7/8 x 7 1/2
252 x 175 x 190
97R 252 x 175 x 190 H5, L2 55L2
11 3/16 x 6 7/8 x 7 1/2
283 x 175 x 190
98R 283 x 175 x 190 H6, L3 66L3
8 1/8 x 6 7/8 x 6 7/8
207 x 175 x 175
99 207 x 175 x 175 T4, LB1 36LB
8 1/4 x 6 7/8 x 6 7/8
210 x 175 x 175
99R 210 x 175 x 175 T4, LB1 36LB
- - 175 x 175 x 190 H3, L0 32L0
- - 297 x 175 x 190 H4, L1 45L1

As one can see, battery sizes are more or less the same, except for the BCI Groups 48 and 49, which differ somewhat more in the batteries' lengths.

Also, the closest DIN/EN H3, L0, 32L0 battery is BCI Group 12T which is somewhat longer and taller, although there few more groups that are more or less similar in size.

The closest DIN/EN H4, L1, 45L1 battery are BCI Group 98R (283 x 175 x 190 mm) that can fit into DIN/EN H4, L1, 45L1 battery compartment and BCI Group 94R (315 x 175 x 190 mm) which is somewhat longer.

Again, when replacing the batteries with the batteries of another 'size', be sure to check terminal types, their orientation, battery edge, and similar details.

bosch s6588b s6 battery m- Battery Type: car batteries are mostly starting batteries, designed for providing bursts of energy required for starting the engine. These Starting, Lighting, and Ignition (LSI) batteries are the most common type of car batteries.

However, due to the increase in power requirements when the engine is turned off, modern starting batteries are more and more designed to tolerate being discharged by audio and other multimedia systems, by security systems, GPS, etc.

Such batteries are essentially dual-purpose batteries and are highly recommended for the single battery systems where the battery is heavily used even when the engine is turned off.

- Battery Chemistry: Most car batteries are lead-acid batteries, although lightweight lithium-ion batteries are becoming more and more common.

However, Sealed Lead-Acid (SLA) Absorbent Glass Mat (AGM) batteries are practically maintenance-free batteries, that are much cheaper than lithium-ion batteries. Wet/flooded lead-acid batteries are being phased out by AGM batteries as starting batteries and by Gel-Cell batteries are deep-cycle batteries in dual battery systems.

Note: some brands also manufacture Gel-Cell starting batteries, but they are not that common.

group24batteries m- Terminal Type and Orientation: Proper terminal types and orientation are required to ensure proper connection of the battery with the car's electrical system.

In the case of the wrong terminal type, one may use special terminal adapters to connect such battery, however, every connection increases electric resistance.

In the case of the wrong terminal orientation, one may use cable extenders that must be rather thick due to the large starting currents.

As one can see, there are solutions for the wrong terminal types and orientation, but getting the battery with the right terminal types and orientation can save a lot of problems.

- Single or Dual Battery Systems: cars with dual battery systems use one starting battery as Starting, Lighting, and Ignition (LSI) battery, and another dual-purpose or deep-cycle battery for powering all other electric and electronic devices while the main engine is turned off. Dual battery systems are more complicated than the single battery systems, but they provide an additional level of security - starting battery is never discharged (car-dependent, although most modern cars with dual batteries monitor the condition of both batteries) below the level required for starting of the main engine.

Single battery systems use starting batteries for Starting, Lighting, and Ignition (LSI) and if they require more electric power when the engine is turned off, then the cars feature either advanced starting AGM battery or pure dual-purpose batteries.

Note: some cars feature backup lead-acid/lithium-ion battery which is not used for powering external loads - these batteries are used for powering onboard computers and rest of car's electronics required for normal car's operation when the main battery is dead or for some reason, fully discharged.

- CCA/MCA, RC, Capacity: There are several definitions of the Cold Cranking Amps, Cranking Amps, Marine Cranking Amps, and other features that describe the ability of the batteries to provide electric power. Most common definitions are:

CCA (Cold Cranking Amps) - maximum current that a new, fully charged, 12V battery can deliver for 30 seconds, with the voltage NOT dropping below 7.2V, at 0°F (-18°C).

CA (Cranking Amps) or MCA (Marine Cranking Amps) - maximum current that a new, fully charged, 12V battery can deliver for 30 seconds, with the voltage NOT dropping below 7.2V at 32°F (0°C).

RC (Reserve Capacity) - this value is the number of minutes that a new, fully charged battery (at 80°F, ~25°C) can deliver 25A current and maintain a voltage above its cut-off value (10.5V for lead-acid batteries).

Capacity (Ah, Amp-hours) - this value describes how many Amps (A) a new, fully charged battery can provide for 20 hours, before the voltage drops below a certain level (10.5V for lead-acid batteries).

odyssey 31m pc2150st m battery m- Car Battery Brands are numerous, with the most popular ones being (alphabetic order) ACDelco, Bosch, Delphi, DieHard, Exide, NorthStar, Odyssey, Optima, VMAXTANKS, XS Power, etc.

Which car battery brand is the best? Well, that is rather hard to say, since we all have different requirements.

If the price is not important, then go for NorthStar or Odyssey battery.

If you are looking for a balanced design, but don't mind paying somewhat more, Optima Batteries are a great choice.

Other brands mentioned here offer reliable batteries, balancing well between their prices and performances.


Top 10 Most Popular Car Battery Sizes

Although there is a large number of potential car battery sizes (100+), 10 most popular battery groups are used in probably at least 95-98% of cars and similar vehicles.

These battery groups include BCI Groups 24, 34/78, 35, 47 (H5, L2, 55L2), 48 (H6, L3, 66L3), 49 (H8, L5, 88L5), 51R, 65, 75 and 94R batteries.

This list does NOT include batteries for Recreational Vehicles (RVs), large trucks, ATVs, industrial batteries, solar, wind, and other off-the-grid batteries and similar.


BCI Group 24 Batteries

northstar nsb agm24f

BCI Group 24 batteries feature dimensions of (L x W x H) 10.25 x 6.8125 x 8.875 inches (260 x 173 x 225 mm), but there are other subgroups present as well:

BCI Group Size L (mm) W (mm) H (mm) L (inches) W (inches) H (inches) Amazon Search
24 260 173 225 10 1/4 6 13/16 8 7/8 Group 24 Battery
24F 273 173 229 10 3/4 6 13/16 9 Group 24F Battery
24H 260 173 238 10 1/4 6 13/16 9 3/8 Group 24H Battery
24R 260 173 229 10 1/4 6 13/16 9 Group 24R Battery
24T 260 173 248 10 1/4 6 13/16 9 3/4 Group 24T Battery

Note: Amazon affiliate links in the chart open in the new windows, feel free to check them.

Physical dimensions of the group 24 batteries are very similar to several other battery groups, allowing these batteries to be used almost interchangeably.

Here is the list of several of such groups with their maximum dimensions (L x W x H):

- Group 78: 10.25 x 7.0625 x 7.6875 inches (26 x 17.9 x 19.6 cm),

- Group 34: 10.25 x 6.8125 x 7.875 inches (26 x 17.3 x 20 cm),

- Group 24: 10.25 x 6.8125 x 8.875 inches (26 x 17.3 x 22.5).

However, group 24 batteries may be easily purchased at most hardware/car stores or online shops and if you do need new group 24 battery, go for one.

The following chart lists some of the most popular BCI Group 24 batteries:

Model Battery Type Chemistry Ah CCA MCA RC Weight (lbs/kg) Review
ACDelco M24AGM Deep Cycle AGM 80 500 625 140 43.0 lbs; ~19.5 kg -
Mighty Max ML75-12 Deep Cycle AGM 77 - - - 50.71 lbs;  ~22.97 kg Mighty Max ML75-12
NorthStar NSB-AGM24F Dual Purpose AGM 76 840 1000 160 57 lbs;  ~25.8 kg -
UPG UB12750 Deep Cycle  AGM  75 - - - 49.1 lbs;  ~22.3 kg -
VMAXTANKS MB107-85 Deep Cycle  AGM  85 - - 170 55 lbs; ~24.9 kg VMAXTANKS MB107-85
VMAXTANKS MR107-85 Deep Cycle  AGM  85 - 700 160 55 lbs; ~24.9 kg  VMAXTANKS MR107-85
VMAXTANKS SLR-85 Deep Cycle  AGM  85 - - 180 55 lbs; ~24.9 kg  VMAXTANKS SLR-85

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

As one can see, BCI Group 24 batteries are mostly deep-cycle and dual-purpose batteries used in cars with dual battery systems.

However, if you need a starting BCI group 24 battery and you are unable to find one, consider getting a starting group 34 battery - they are smaller and lighter, but they are optimized for starting/cranking applications and can provide stronger currents than deep-cycle group 24 batteries.

Model Battery Type Chemistry Ah CCA MCA RC Weight (lbs/kg) Review
ACDelco 34AGM Starting AGM 60 740 - 115 38.7 lbs; 17.4 kg -
Banshee 34M Dual Purpose Flooded 66 750 870 100 37.0 lbs; 16.8 kg -
Delphi BU9034 Starting AGM 55 775 - 120 42.5 lbs; 19.3 kg -
DieHard 38232 Starting AGM 55 775 - 120 44.5 lbs; 20.2 kg DieHard 38232
Exide Edge FP-AGM34 Dual Purpose AGM 60 770 - 120 45.9 lbs; 20.8 kg -
NorthStar NSB-AGM34 Dual Purpose AGM 65 880 1050 134 51 lbs; 23.1 kg -
Odyssey 34M-PC1500 Dual Purpose AGM 68 850 1050 135 49.5 lbs; 22.4 kg 34M-PC1500
Optima RedTop 34 Starting AGM 50 800 1000 100 37.9 lbs; 17.2 kg Optima RedTop 34
Optima 8016-103 D34M Dual Purpose AGM 55 750 870 120 43.5 lbs; 19.7 kg Optima D34M
VMAXTANKS XTR34-75 Deep Cycle AGM 75 - 825* 145 45.0 lbs; 20.4 kg VMAX XTR34-75
XS Power D3400 12V 65 Ah Dual Purpose AGM 65 - 1000 135 46.0 lbs; 20.85 kg XS Power D3400
XS Power D3400 12V 80Ah Dual Purpose AGM 80 - 1150 160 50 lbs; 22.67 kg

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

BCI Group 24 batteries feature a nominal capacity of 75-85 Ah, 500-840 CCA, 625-1000 MCA, and RC value between 140 and 180 minutes.

BCI Group 34 batteries feature a nominal capacity of 50-80 Ah, 740-880 CCA, 825-1150 MCA, and RC value between 100 and 160 minutes.

Note: Although it is considered deep cycle battery, VMAXTANKS XTR34-75 features 1100 HCA (Hot Cranking Amps) - its MCA value of 825 Amps is a value calculated using the formula:

MCA = HCA x 0.75 = 1100 Amps x 0.75 = 825 Amps

It is an approximation, but it shows how that battery strong is.

 


BCI Group 34/78 Batteries

optima 34 78 redtop w300px

Since groups 34 and 78 are so similar in dimensions, many manufacturers offer batteries labeled as '34/78' - these batteries feature both top SAE terminals (like group 34 batteries have) and side 3/8" terminals (like group 78 batteries have).

Also, such batteries often have letters 'DT' (Dual Terminals) as part of their labels in order to distinguish them from 'common' group 34 and group 78 batteries.

The following comparison chart lists some of the best and most popular group 78 and group 34/78 batteries with some of their features and specifications:

Model Battery Type Chemistry Ah CCA MCA RC Weight (lbs/kg) Review
ACDelco 78AGM Starting AGM 60 740 890 115 37.8 lbs; 17.2 kg -
Delphi BU9078 MaxStart Starting AGM 55 775 - 120 43 lbs; 19.5 kg -
Northstar NSB-AGM34/78 Dual Purpose AGM 65 880 1050 134 51 lbs; 23.1 kg -
Northstar NSB-AGM78 Dual Purpose AGM 65 880 1050 134 51 lbs; 23.1 kg -
Odyssey 34/78-PC1500DT Dual Purpose AGM 68 850 1050 135 49.5 lbs; 22.4 kg Odyssey 34/78
Odyssey 78 PC1500 Dual Purpose AGM 68 850 1050 135 49.5 lbs; 22.4 kg -
Optima 8004-003 34/78 RedTop Starting AGM 50 800 1000 100 38.8 lbs; 17.6 kg Optima 34/78 RedTop
Optima 8014-045 D34/78 YellowTop Dual Purpose AGM 55 750 870 120 43.5 lbs; 19.7 kg Optima D34/78 YellowTop
Optima 8078-109 78 RedTop Starting AGM 50 800 1000 100 39.5 lbs; 17.9 kg -

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

Most popular BCI Group 34/78 batteries are practically all AGM batteries having nominal capacity in the 50-70 Ah range, 740-880 CCA, 870-1050 MCA, and RC values between 100-135 minutes.

As one can see NorthStar and Odyssey 34/78 dual-purpose batteries feature the best performances, although they tend to cost more than other batteries.

Optima 34/78 RedTop battery features excellent starting characteristics and is robust and very vibration resistant battery.

 


BCI Group 35 Batteries

odyssey 35 pc1400 w250

BCI Group 35 batteries feature physical dimensions of (L x W x H) 9 1/16 x 6 7/8 x 8 7/8 inches (9.0625 x 6.875 x 8.875 inches, 230 x 175 x 225 mm), while their electrical features depend on the battery design, intended use, chemistry, etc.

The following chart lists the most popular group 35 batteries, with their most important features:

Model Battery Type Chemistry Ah CCA MCA RC Weight Review
Arc-Angel Group 35 Starting LiFePO4 40 900 - - 16 lbs; 7.3 kg -
Delphi BU9035 Dual Purpose AGM 50 680 - 100 40 lbs; 18.1 kg -
DieHard 38275 Dual Purpose AGM  50 650 - 100 42 lbs; 19.0 kg -
NorthStar NSB-AGM35 Dual Purpose  AGM 60 740 880 115 49 lbs; 22.2 kg -
Optima 8020-164 35 RedTop Starting  AGM 44 720 910 90 31.7 lbs; 14.4 kg Optima 35 RedTop
Optima 8040-218 35 YellowTop Dual Purpose  AGM 48 620 770 98 36.4 lbs; 16.5 kg -
Odyssey 35-PC1400T Dual Purpose  AGM 65 850 950 130 50 lbs; 22.7 kg -

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Group 35 batteries are medium size batteries, featuring 20h capacity in 44-65 Ah range, 620-850 CCA, 770-950 MCA, RC of 90-130 minutes, etc.

Group 35 batteries are somewhat shorter than group 34 batteries, but are also one inch (25.4 mm) taller - these battery groups feature very similar electrical characteristics, just be sure to check terminal types/orientation and casing/battery compartment size.


BCI Group 47 (H5, L2, 55L2) Batteries

acdelco 47agm w250

BCI Group 47 batteries are considered to be equivalent to DIN H5 (L2) and EN 55L2 batteries.

BCI Group 47 batteries feature physical dimensions of 9 11/16 x 6 7/8 x 7 1/2 inches (246 x 175 x 190 mm), while DIN H5 (L2) and EN 55L2 batteries maximum dimensions are 242 x 175 x 190 mm.

The following chart lists the most popular group 47 batteries, with their most important features:

Model Battery Type Cell Type Ah CCA MCA RC Weight (lbs/kg) Review
ACDelco 47AGM Professional Starting AGM 60 630 - 115 39.2 lbs; 17.8 kg -
Delphi BU9047 MaxStart Starting AGM 60 600 - 100 38.5 lbs; 17.5 kg -
XS Power D4700 BCI Group 47 AGM Battery Dual Purpose AGM 50 - 745 105 41.2 lbs; 18.7 kg -

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BCI group 47 batteries are not as common as some other battery groups, but ACDelco and Delphi manufacture very similar staring models that feature a nominal capacity of 60Ah, 630 and 600 CCA and 115 and 100 minutes RC.

XS Power D4700 battery is labeled as a dual-purpose battery, but it is primarily designed for powering strong audio and multimedia systems while the main engine is turned off.


BCI Group 48 (H6, L3, 66L3) Batteries

northstar nsb agm48

BCI Group 48 batteries are considered to be equivalent to DIN H6 (L3) and EN 66L3 batteries.

BCI Group 48 batteries feature physical dimensions of 12 1/16 x 6 7/8 x 7 9/16 inches (306 x 175 x 192 mm), while DIN H6 (L3) and EN 66L3 batteries maximum dimensions are 278 x 175 x 190 mm.

As one can see, there is a difference of around 28 mm (~1.1 inches) in length between these two standards - battery compartments intended for BCI Group 48 batteries are large enough to store DIN H6/L3 (EN 66L3) battery, but the other way around could be problematic.

However, BCI Battery Group 98R batteries feature physical dimensions of 283 x 175 x 190 mm, and is a better match to the DIN H6 (L3) and EN 66L3 batteries - it is also longer, but only by 5 mm (~0.2 inches).

The following chart lists the most popular group 48 batteries, with their most important features:

Model Battery Type Cell Type Ah CCA MCA RC Weight (lbs/kg) Review
ACDelco 48AGM Professional Starting AGM 70 760 - 120 45.5 lbs; 20.6 kg -
Delphi BU9048 MaxStart Starting AGM 70 760 - 120 45.5 lbs; 20.6 kg -
NorthStar NSB-AGM48 Dual Purpose AGM 69 775 880 135 48 lbs; 21.8 kg -
Odyssey Battery 48-720 Battery Dual Purpose AGM 69 723 842 130 48 lbs; 21.8 kg -
Optima Batteries DH6 YellowTop Dual Purpose AGM 72 800 928 140 54 lbs; 24.5 kg -
XS Power D4800 Dual Purpose AGM 60 - 815 120 47.6 kg; 21.6 kg -

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

BCI Group 48 (H6, L3, 66L3) batteries feature a nominal capacity of 60 to 70 Ah, 720-800 CCA, 800-930 MCA, and RC values between 120 and 140 minutes.

ACDelco and Delphi group 48 batteries are designed as starting batteries, but they tolerate being discharged with car's onboard electronics, but not enough to be considered as true dual-purpose batteries.

NorthStar, Odyssey and Optima group 48 batteries are dual-purpose batteries, being able to crank surprisingly large engines (for dual-purpose batteries) and still be able to tolerate a large number of charging and discharging cycles.

XS Power D4800 is a dual-purpose battery, but intended mostly to power audio and other multimedia devices while the engine is turned off.


BCI Group 49 (H8, L5, 88L5) Batteries

exide edge fp agm l5 49 flat plate w250

BCI Group 49 batteries are considered to be equivalent to DIN H8 (L5) and EN 88L5 batteries.

BCI Group 49 batteries feature physical dimensions of 15 x 6 7/8 x 7 3/16 inches (381 x 175 x 192 mm), while DIN H8 (L5) and EN 88L5 batteries maximum dimensions are 354 x 175 x 190 mm.

As one can see, there is a difference of around 27 mm (~1.06 inches) in length between these two standards - battery compartments intended for BCI Group 49 batteries are large enough to store DIN H8 (L5) and EN 88L5 batteries, but the other way around could be problematic.

The following chart lists the most popular group 49 batteries, with their most important features:

Model Battery Type Cell Type Ah CCA MCA RC Weight (lbs/kg) Review
ACDelco 49AGM Professional Starting AGM 95 900 - 160 58.6 lbs; 26.6 kg -
Bosch S6588B S6 Flat Plate AGM Battery Starting AGM 92 850 - 160 61.9 lbs; 28.1 kg -
Deka 9AGM49 AGM Intimidator Battery Starting AGM 92 850 975 170 58.5 lbs; 26.5 kg -
Exide Edge FP-AGML5/49 Flat Plate AGM Dual Purpose AGM 92 850 - 160 59.8 lbs; 27.1 kg -
Odyssey 49-950 Performance Dual Purpose AGM 94 950 1150 160 62.8 lbs; 28.5 kg -
XS Power D4900 Dual Purpose AGM 80 - 1075 168 59 lbs; 26.8 kg -

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

BCI Group 49 (H8, L5, 88L5) batteries feature a nominal capacity of 80-95 Ah, 850-950 CCA, 975-1150 MCA, and RC values between 160 and 170 minutes.

ACDelco, Bosch, and Deka manufacture rather strong starting group 49 batteries, while Exide and Odyssey offer rather strong dual-purpose batteries that also tolerate deep discharge applications.

XS Power D4900 battery is dual-purpose battery that can provide plenty of Amps, but it is primarily designed for powering of audio and other similar car systems while the engine is turned off.


BCI Group 51 and 51R Batteries

optima group51 batteries

BCI Groups 51 and 51R batteries feature physical dimensions of 9.374 x 5.0625 x 8.8125 inches (238 x 129 x 223 mm) and are manufactured as Group 51 (positive terminal to the LEFT) and as Group 51R (positive terminal to the RIGHT).

The following chart lists some of the most popular Group 51 and Group 51R batteries, with their most important features:

Model Battery Type Cell Type Ah CCA MCA RC Weight (lbs/kg) Review
ACDelco ACDB24R Dual Purpose AGM 45 325 390 70 29.11 lbs; 13.2 kg -
Deka/East Penn 8AMU1R Starting AGM - 320 400 45 25 lbs; 11.3 kg -
Delphi BU9051P MaxStart Dual Purpose AGM 46 325 390 60 29.5 lbs; 13.4 kg -
Optima 8071-167 D51 Dual Purpose AGM 38 450 575 66 26 lbs; 11.8 kg -
Optima 8073-167 D51R Dual Purpose AGM 38 450 575 66 26 lbs; 11.8 kg -
VMAXTANKS SLR60 Deep Cycle AGM 60 - - 135* 43 lbs; 19.5 kg -
XS Power D5100 XS Dual Purpose AGM 66 745 872 131* 43.2 lbs; 19.6 kg -
XS Power D5100R XS Dual Purpose AGM 66 745 872 131* 43.2; 19.6 kg -

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

Also, batteries marked with '*' are slightly wider than 5.0625 inches (129 mm). These batteries actually don't belong to Group 51 or 51R, but to the Group 22NF featuring a size of 9.4375 x 5.5 x 8.9375 inches (240 x 140 x 227 mm), but they are nonetheless labeled as Group 51/51R batteries.

Group 51/51R batteries feature a nominal capacity of 38-66 Ah, 320-750 CCA, 390-870 MCA, and RC values between 45 and 135 minutes.

As one can see, these are very different values, since some models are starting batteries, some dual-purpose, and some models are true deep-cycle batteries with thick plates designed to withstand a large number of deep cycle discharges.

 


BCI Group 65 Batteries

odyssey 65 pc1750t battery

BCI Group 65 batteries feature physical dimensions of (L x W x H) 12 1/2 x 7 1/2 x 7 9/16 inches (12.0625 x 7.5 x 7.5625 inches, 306 x 190 x 192 mm), or for short 12.1 x 7.5 x 7.6 inches.

Most popular BCI Group 65 batteries are given in the following chart:

Model Battery Type Cell Type Ah CCA MCA RC Weight (lbs/kg) Review
ACDelco 65AGMHR Dual Purpose AGM 70 775 960 150 45.9 lbs; 20.8 kg -
Deka 9A65 Dual Purpose AGM 75 775 955 150 46 lbs;  20.85 kg -
Delphi BU9065 65 Dual Purpose AGM 75 750 - 150 47.5 lbs; 21.5 kg -
NORTHSTAR NSB-AGM65 Dual Purpose AGM 69 930 1070 135 55 lbs; 24.9 kg -
Odyssey 65-PC1750T Dual Purpose AGM 74 950 1070 145 54 lbs; 24.5 kg -
Renogy RBT100LFP12S-G1 Deep Cycle Lithium 100 - - ~230 26 lbs; 11.8 kg Renogy 12V 100Ah Deep Cycle Batteries

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BCI Group 65 AGM batteries feature a nominal capacity of 70-75 Ah, 750-950 CCA, 950-1070 MCA, RC values between 130-150 minutes and they weigh between 45 and 55 pounds (20-25 kg).

BCI Group 65 lithium-ion batteries are not as common as AGM batteries, but they are much lighter, feature larger capacity, and much longer RC value.

For example, the Renogy RBT100LFP12S-G1 lithium-ion battery feature nominal capacity of 100 Ah, RC value of 230 minutes, and it weighs only 26 pounds (11.8 kg).

Also, it features maximum continuous discharge current of 100 Amps, 130 Amps one-minute current, cut-off current of 150 Amps, maximum allowed charging current of 50 Amps, very large number of charging and discharging cycles, and 5-year limited warranty.

But, it also costs more than AGM Group 65 batteries.

Group 65 1000 CCA Battery - from time to time people ask if there is a group 65 battery being capable of delivering 1000+ CCA Amps.

Well, NorthStar NSB-AGM65 and Odyssey 65-PC1750T batteries are very close to delivering 1000 CCA (930 and 950 CCA respectively), but not even them are able to produce such current at such low temperatures.

If you need 1000+ CCA battery, please check Other Battery Groups later in this article.


BCI Group 75 Batteries

odyssey extreme 75 pc1250 w250

BCI Group 75 batteries feature physical dimensions (L x W x H) of 9 1/16 x 7 1/16 x 7 11/16 inches (230 x 179 x 196 mm) and are very similar to physical dimensions of:

- BCI Group 25 Batteries: 9 1/16 x 6 7/8 x 8 7/8 inches (230 x 175 x 225 mm),

- BCI Group 85/86 Batteries: 9 1/16 x 6 13/16 x 8 inches (230 x 173 x 203 mm).

Thus, some manufacturers create batteries with dual-terminals and label them as 75/25 and 75/86 batteries.

The following chart lists some of the most popular group 75, 75/25 and 75/86 batteries:

Model Battery Type Cell Type Ah CCA MCA RC Weight (lbs/kg) Review
Delphi BU9075DT MaxStart Starting AGM 60 680 - 100 41.0 lbs; 18.6 kg -
Odyssey 75-PC1230 Dual Purpose AGM 55 760 815 110 45.5 lbs; 20.6 kg -
Odyssey 75/86-PC1230DT Dual Purpose AGM 55 760 815 110 45.5 lbs; 20.6 kg -
Optima 8022-091 75/25 RedTop Starting AGM 44 720 910 100 33.1 lbs; 15.0 kg -
Optima 8042-218 D75/25 YellowTop Dual Purpose AGM 48 620 770 98 37.8 lbs; 17.2 kg -

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

BCI group 75, 75/25, and 75/86 batteries feature a nominal capacity of 44-60 Ah, 620-760 CCA, 770-910 MCA, and RC values between 100 and 110 minutes.

As usual, Optima batteries are lighter than other batteries of the same battery group due to their round wound cells, creating very vibration resistant batteries, but also easily providing very similar CCA and MCA currents like other, heavier batteries.

Odyssey manufactures two batteries in this group (75 and 75/86 batteries) with excellent starting and deep cycle performances - tough and durable, true dual-purpose batteries that come at an acceptable price.


BCI Group 94R Batteries

acdelco 94ragm

BCI Group 94R battery physical dimensions are (L x W x H) 12.4 x 6.9 x 7.5 inches (315 x 175 x 190 mm) and they weigh on average around 52 - 57 pounds (23.6 - 25.8 kg).

Due to their size, most modern group 94R batteries are dual-purpose batteries, featuring a nominal capacity of 75-80Ah, 800-850 CCA, and RC values between 140 and 160 minutes.

The following chart lists some of the most popular group 94R batteries:

Model Battery Type Chemistry Ah CCA MCA RC Weight (lbs/kg) Review
ACDelco 94RAGM Dual Purpose AGM 80 800 - 140 51.6 lbs; 23.4 kg -
Deka 9A94R Dual Purpose AGM 80 800 - 140 51.5 lbs; 23.3 kg -
Delphi BU9094R Dual Purpose AGM 80 800 - 140 52 lbs; 23.6 kg -
Exide Edge FP-AGML4/94R Dual Purpose AGM 80 800 - 140 53.3 lbs; 24.1 kg -
NorthStar NSB-AGM94R Dual Purpose AGM 76 840 - 158 57 lbs; 25.8 kg -
Odyssey 94R-850 Dual Purpose AGM 80 850 - 150 54.8 lbs; 24.9 kg -

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

High-performance group 94R batteries are NorthStar NSB-AGM94R and Odyssey 94R-850, having RC values of 158 and 150 minutes and 840 and 850 CCA respectively.

Surprisingly, NorthStar NSB-AGM94R is not the best 20h performer, featuring a somewhat lower nominal capacity.

Other brands manufacture well balanced AGM designs, with somewhat lower CCA and RC values, but their batteries also often come at lower prices, when compared with NorthStar and Odyssey batteries.


Other Battery Groups

odyssey 31m pc2150st m battery 2

There are several other BCI battery groups commonly used in other types of vehicles, in industrial applications, security systems, as marine batteries, off-the-grid applications, and similar.

These BCI groups include:

- BCI Group BTX14-BS: physical dimensions (L x W x H) of 5.875 x 3.4375 x 5.75 inches (150 x 87 x 146 mm), 12Ah, 200 CCA - Powersports battery, also labeled as YTX14-BS, CTX14-BS, STX14-BS, PTX14-BS, etc.

- BCI Group 27: physical dimensions (L x W x H) of 12 1/16 x 6 13/16 x 8 7/8 (306 x 173 x 225 mm), 66-110 Ah, 600-1000 CCA, 140-220 minutes RC, 54-70 pounds.

- BCI Group 31: physical dimensions (L x W x H) of 13 x 6 13/16 x 9 7/16 inches (330 x 173 x 240 mm), 75-135 Ah, 600-1150 CCA, 155-240 minutes RC, 60-75 lbs AGM, 28-31 lbs Lithium-ion.

- BCI Group 8D: physical dimensions (L x W x H) of 20 3/4 x 11 1/8 x 9 7/8 inches (527 x 283 x 250 mm), 200-350 Ah, 1450-2250 CCA, 480-780 minutes RC, 128-187 lbs AGM, ~80 lbs Lithium-ion.


How to Charge the Car Battery

car battery amps mAs long as the car's charging system is working properly, there is no need to additionally charge the battery.

If the battery is discharged for whatever reason (parasite load, lights turned on, etc), and is unable to crank the engine, jump-start the engine and let the alternator recharge the battery for at least 1-2 hours.

However, if the battery is discharged and must be recharged, please check the car's manual:

- some cars don't allow the battery to be recharged while connected to the car's electric system, especially not with advanced battery chargers that feature desulphation charging mode.

- some cars don't allow the battery to be disconnected from the car's electric system, not even if it is discharged and unable to crank the engine.

- some cars feature backup batteries that allow the user to take the main battery out of the car for days/weeks to come and not bothering their users about various pins and potential security issues - some modern cars are just computers with wheels...

- some cars allow the user to remove the battery from the car's electric system, but require the user to enter just one security pin after connecting the battery.

After sorting things out how to actually charge the battery (in the car, out of the car), get an advanced AGM battery charger that charges car's battery using several charging modes after analyzing the battery.

It is important that such battery charger also features desulphation mode and equalization mode:

- desulphation mode: charger sends spikes of current in order to 'break' deposits of lead-sulphate from the battery's plates.

- equalization mode: charger charges the battery with the constant low current in order to equalize the charge of the individual battery cells.

Note: advanced AGM battery chargers should NOT be used for charging lithium batteries, unless they have a custom 'Lithium Battery Charging Mode'.

Depending on the battery size, AGM battery chargers in the 10-15 Amps range are recommended for charging the car's batteries.

For example, if You have 75 Ah battery drained down to 50% DoD (Depth of Discharge), 15 Amps AGM battery charger will charge it in slightly more than 3 hours.

If You have 12-15 Ah Powersports battery, consider using 1-3 Amps battery chargers - AGM and all other batteries have a maximum allowed charging current and if they are charged with stronger currents, their operating time is decreased, to say the least (some batteries may overheat and burst to flames!).


car pull overLong Story Short: When looking for your next car battery, check the actual size of your battery compartment, and check your current battery, including its chemistry, type, capacity, CCA, actual size, terminal types, terminal orientation, and how it is secured to the car.

After that, You can consider getting your next battery that features the same or better characteristics and that can be properly charged by the car's onboard charging system.

Note: If You are not into the car DIY activities, consider taking your car to the authorized car workshop, and let the certified personnel replace the failing car's battery.