Group 35 Batteries - Dimensions, Features, and Recommendations

BCI Group 35 batteries are very popular battery size of lead-acid batteries, commonly used in cars, trucks, RVs, and other similar applications as starting or dual-purpose batteries.

These batteries, especially dual-purpose and deep cycle batteries, are often used in other applications as well, like UPS batteries, wheelchair batteries, security system backup batteries, medical applications, off-the-grid, etc.

The most popular BCI Group 35 batteries are Absorbent Glass Mat (AGM) Sealed Lead Acid (SLA) batteries, but lithium iron phosphate (LiFePO₄) batteries are slowly entering the market, especially for dual-purpose applications.

Updated: January 9, 2023.

Group 35 batteries are medium size batteries featuring 20h capacity in the 42-65 Ah range, providing 430-850 Cold Cranking Amps (CCA), 90-130 minutes Reserve Capacity, etc.

Their physical dimensions are approximately (LxWxH) 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 depending on the battery design, intended use, chemistry, etc.

Group 35 Batteries Comparison Chart

The following chart lists the most popular group 35 batteries, with their most important features (batteries are ordered alphabetically):

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

Group 35 Batteries Dimensions, Weight, Chemistry, Features

Again, the physical dimensions of Group 35 batteries are approximately (LxWxH) 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) - we have to emphasize this since many group 35 batteries are slightly longer than "standard maximum length."

This difference is not large - some of the batteries are less than half of an inch longer than they should be, but since they are intended mostly for cars and similar applications with some room to spare around the battery, they can easily fit such battery compartments.

Nonetheless, be sure to measure the battery compartment first and check that the battery may fit such battery compartment even if it is somewhat larger than the recommended standard.

Most group 35 batteries are spill-proof AGM batteries, designed either as dual-purpose or as starting batteries.

Some of the models are declared as dual-purpose batteries, but in essence, they are starting batteries with increased tolerance toward cycling applications, which is very important for modern vehicles where the main battery has to provide large currents in order to start the main engine (gas, diesel), but also it has to be able to power different electric and electronic systems while the engine is turned off, like audio systems, ventilators, lights, security systems, etc.

Lead-acid group 35 batteries are mostly dual-purpose AGM batteries, featuring strong starting currents, but thanks to improvements in AGM battery technology, they can also cycle well, at least when compared with wet/flooded lead-acid batteries.

AGM lead-acid batteries are spill-proof, maintenance-free batteries that are heavier than lithium batteries, and they don't cycle as well as lithium batteries.

But, AGM group 35 batteries are very reliable batteries and can operate even in very low temperatures.

Lithium-ion batteries are present in the form of Lithium Iron Phosphate (LiFePO₄) batteries, which is practically the safest lithium battery chemistry type.

Lithium-ion batteries feature Battery Management Systems (BMS) that monitor battery parameters, and if necessary, they protect the battery by cutting it off from the rest of the electric circuit - they offer over-voltage, over-charge, over-current, over-discharge,  high- and low-temperature protection, and they also often balance individual cells.

Such Battery Management Systems ensure that lithium-ion batteries may be used as drop-in replacements for AGM SLA batteries.

Considering their weight, lithium-ion batteries, as starting batteries, easily outperform AGM batteries with ease.

Note: Lithium batteries are sensitive to low temperatures, and in such conditions, their BMS can simply disconnect the battery from the car's electric system. Something like that can never happen to AGM lead-acid batteries.

Here are our short reviews of the most popular AGM and lithium group 35 batteries (batteries are ordered alphabetically):

Arc-Angel Group 35 LiFePO4 Battery

Arc-Angel Group 35 LiFePO₄ Battery is a true starting/cranking battery with a CCA value of 900 Amps.

Its physical dimensions are 9.37x6.77x8.70 inches (238x172x221), so it is slightly longer than the 'standard' group 35 battery.

But, it weighs only 16 pounds (15.99 pounds according to the manufacturer), which is half of the Optima 8020-164 35 RedTop AGM starting battery and less than one-third of the Odyssey 35-PC1400T and NorthStar NSB-AGM35.

Arc-Angel Group 35 LiFePO4 Battery is designed as a drop-in replacement for group 35 AGM/Gel-Cell/Wet lead-acid batteries and may be charged with onboard alternators.

However, it is recommended by the manufacturer to charge it, if possible, with lithium-ion battery chargers. Its nominal capacity is 40 Ah.

It is a maintenance-free battery, with an extra-low self-discharge rate - it is claimed by the manufacturer that it is able to start the car even after one year of storage.

Since these batteries are not very long on the market, at least not when being compared with AGMs, reviews from other users are not very numerous, although the battery itself is often praised by the users.

Arc-Angel Group 35 LiFePO4 Battery comes with a 10-year(!) warranty.

For the most up-to-date offers and prices, feel free to check the Arc-Angel Group 35 Amazon link (the link opens in the new window).

Bosch S6523B S6 Flat Plate AGM Battery

The Bosch S6523B AGM group 35 battery is a robust and reliable battery designed for good performances in both low and high temperatures.

It accepts charge well, allowing it to be used in vehicles with Start/Stop systems. Also, it is recommended for vehicles with short driving distances since it recharges rather quickly after cranking the engine.

Bosch S6523B AGM group 35 battery weighs ~40 pounds (~18.1 kg), it features 53Ah 20h capacity, Reserve Capacity of 110 minutes, 650 Amps CCA rating, and 780 Amps MCA rating.

It is a very good starting battery that cycles well and comes with a 4-year free replacement/pro-rata warranty.

For the most up-to-date offers and prices, feel free to check the Bosch S6523B AGM Group 35 Battery Amazon link (the link opens in the new window).

NorthStar NSB-AGM35 AGM Group 35 Battery

NorthStar NSB-AGM35 is a true 'heavyweight' among the group 35 batteries, and it weighs 49 pounds, just one pound less than the Odyssey 35-PC1400T battery.

But, NorthStar NSB-AGM35 is also an excellent performer, featuring 60 Ah capacity, 740 CCA, 880 MCA, and 115 minutes RC - it is the only dual-purpose battery that comes close to the Odyssey group 35 battery in terms of performance.

NorthStar NSB-AGM35 physical dimensions are (LxWxH) 9.45x6.76x8.54 inches - another slightly longer than the 'standard' group 35 battery.

NorthStar NSB-AGM35 uses plates made of pure lead, ensuring good starting features and deep cycle applications - the battery is able to cycle over 900x when being discharged down to 50% DoD (Depth of Discharge).

Price? Well, what you pay is what you get - an excellent and reliable battery with a very nice price tag.

For the most up-to-date offers and prices, feel free to check the NorthStar NSB-AGM35 AGM Group 35 Battery Amazon link (link opens in the new window).

Optima Batteries 8020-164 35 RedTop Starting Battery

Optima 8020-164 RedTop is the only 'true' AGM lead-acid starting battery on our list.

Optima 8020-164 RedTop is made using spiral-wound plates, offering a large surface at a relatively low weight - it weighs only 31.7 pounds, which is ~65% of NorthStar NSB-35AGM and Odyssey 35-PC1400T battery.

In terms of starting/cranking performances, Optima 8020-164 RedTop features 720 CCA (740 CCA NorthStar, 850 CCA Odyssey) and 910 MCA (880 MCA NorthStar, 950 MCA Odyssey) - excellent cranking characteristics for such a lightweight AGM battery.

Optima 8020-164 RedTop physical dimensions are 9.38 x 6.75 x 7.69 inches (it is also wider than the 'standard' 9 1/16").

20h capacity is 'just' 44 Ah, and RC value is 90 minutes - Optima 8020-164 RedTop is not designed for anything but cranking/starting applications.

For the most up-to-date offers and prices, feel free to check the Optima Batteries 8020-164 35 RedTop Starting Battery Amazon link (the link opens in the new window).

Optima 8040-218 D35 YellowTop Dual Purpose Battery

Optima 8040-218 D35 YellowTop features the same design philosophy as Optima 8020-164 RedTop battery - spiral wound plates, AGM battery type.

Optima 8040-218 YellowTop is intended for both starting and deep cycling applications, making it a true dual-purpose battery that can provide 620 CCA, 770 MCA, 98 minutes RC, and features 48 Ah 20h capacity.

Also, it is slightly heavier than RedTop - 36.4 vs. 31.7 pounds, while the physical dimensions are the same.

Generally, Optima 8040-218 YellowTop is not as popular as the RedTop version, but it is, nonetheless, one of the most popular group 35 batteries, used in a broad range of applications where both starting power and deep discharges are required.

For the most up-to-date offers and prices, feel free to check the Optima 8040-218 D35 YellowTop Dual Purpose Battery Amazon link (the link opens in the new window).

Odyssey 35-PC1400T Automotive and LTV Battery

Odyssey 35-PC1400T is the heaviest AGM SLA group 35 battery on our list - it weighs 50 pounds (22.7 kg), but it also outperforms other AGM batteries as well:

- 20h capacity is 65 Ah - nearest rival is NorthStar NSB-AGM35 with a capacity of 60 Ah,

- CCA rating of 850 Amps - nearest rival is NorthStar NSB-AGM35 with 740 CCA Amps,

- MCA rating of 950 Amps - nearest rival is Optima 35 RedTop with 910 MCA Amps,

- RC value of 130 minutes - nearest rival is NorthStar NSB-AGM35 with an RC value of 115 minutes,

- it weighs 50 pounds - the nearest rival is NorthStar NSB-AGM35 weighing 49 pounds.

Odyssey 35-PC1400T is a true dual-purpose battery - obviously, it is an excellent starting battery, but it is also designed to tolerate at least 400 cycles down to 80% DoD (20% SoC - State of Charge).

It can be fully recharged in 4-6 hours with no adverse effects on the battery.

Also, it is able to operate down to -40°F (-40°C) with somewhat decreased cranking amps, but nonetheless, that is a very low temperature - at those temperatures, lithium batteries are probably permanently damaged, while other lead-acid batteries are heaving huge performance issues (if such a low temperature did not already damage them).

With 3-10 years of service life, and a non-spillable and maintenance-free design, Odyssey 35-PC1400T is one of the best, if not the best, group 35 AGM battery.

Note: The author of this article is somewhat biased toward batteries with exceptional low-temperature performances - and Odyssey batteries are such batteries.

Price? Well, just like the NorthStar NSB-AGM35 battery, what you pay is what you get - an excellent, tough, and reliable battery with a very fine price tag :)

For the most up-to-date offers and prices, feel free to check the Odyssey 35-PC1400T Automotive and LTV Battery Amazon link ( the link opens in the new window).

Odyssey ODP-AGM35 Performance Series AGM Battery

Unlike the Odyssey 35-PC1400T battery, which is part of the Odyssey Extreme series, the Odyssey ODP-AGM35 battery is part of the Odyssey performance series, offering not-so-good discharge performances, but it is lighter and often offered at a somewhat cheaper price.

Odyssey ODP-AGM35 battery weighs 45.9 pounds (20.8 kg) and features a 20h capacity of 59Ah, 110 minutes RC, and 675 Amps CCA.

Note: some of these values are clearly stated on the battery's casing.

On the other hand, the official Odyssey website states 765 Amps CCA, 770 Amps MCA, 900 Amps HCA, RC 117 minutes, and weight of 50.0 pounds (22.7 kg).

Personally, this 765 Amps CCA is "too much" for 770 Amps MCA and 900 Amps HCA, so the actual value is most probably "675 Amps CCA" and NOT "765 Amps CCA".

Regardless of this confusion about the battery's performances, the battery is a good low and high-temperature performer, but not as good as Odyssey 35-PC1400T.

For the most up-to-date offers and prices, feel free to check the Odyssey ODP-AGM35 Performance Series AGM Battery Amazon link (the link opens in the new window).

Long Story Short: If You are looking for a group 35 AGM starting battery, Optima RedTop is an excellent choice - it is a very good performer, especially considering its weight.

If you are looking for a good, all-around group 35 battery, consider Delphi, DieHard, or Optima YellowTop batteries - they all have their own pros and cons, just note that countless users have already tested the Optima YellowTop in various real-life situations.

But, Delphi and DieHard models are more affordable batteries than Optima.

And if you are looking for the best performer group 35 battery, consider either NorthStar NSM-AGM35 or Odyssey 35-PC1400 batteries - Odyssey clearly outperforms NorthStar by a nice margin, but they are both good and reliable batteries.

If the price difference is large enough, go for the cheaper one, and if not, Odyssey 35-PC1400T is the right choice.