BCI Group 85 and Group 86 Batteries - Dimensions, Features, and Recommendations

BCI Group 85 and Group 86 batteries share the very same physical dimensions, with the only difference being the battery terminals orientation.

BCI Group 85 and 86 batteries are designed mostly as starting/cranking batteries and are, as such, commonly used in automotive and marine applications for starting smaller and mid-range gas and diesel engines.

Published: February 17, 2022.

BCI Group 85 and BCI Group 86 Batteries Features and Specifications

BCI Groups 85 and 86 batteries feature physical dimensions of 9 1/16 x 6 13/16 x 8 inches (9.0625 x 6.8125 x 8 inches, 230 x 173 x 203 mm), a nominal voltage of 12V, a nominal capacity of 45-55 Ah, Reserve Capacity value of 90-95 minutes, CCA value of 500-750 Amps and MCA value of 650-800 Amps.

By default, BCI Groups 85 and 86 batteries are lead-acid batteries with weight usually in the 31-46 pounds (14.1 - 20.8 kg) range.

The reason for such a broad weight range is that some of the batteries are designed as starting/cranking batteries and some of the batteries are designed as dual-purpose batteries and as such have thicker and heavier plates.

BCI Groups 85 and 86 batteries are almost exclusively lead-acid batteries with cells being either wet/flooded or Absorbent Glass Mat (AGM) cells - Gel-Cell batteries are very rare, at least in this size.

Note: gel-cells starting batteries are usually smaller Powersports batteries.

Lithium drop-in replacement batteries are still not very common in this BCI battery size.

Group 85 vs Group 86 Batteries

Although BCI Groups 85 and 86 batteries share the same physical dimensions, they differ in the battery terminals orientation.

When viewed from the front (battery terminals are closer to the person looking at the battery), BCI Group 86 batteries feature a positive battery terminal on the left and negative to the right side of the battery.

On the other hand, BCI Group 85 batteries, when viewed from the front, feature a negative battery terminal to the left and a positive battery terminal to the right - one may say that the group 85 batteries are actually group 86R batteries.

In theory, it is possible to replace the group 85 battery with the group 86 battery if, and only if the battery cables are long enough to compensate for the different position of the battery terminals - assuming that the batteries' hold-down edges are the same or at least compatible.

The following comparison chart lists some of the most popular BCI Groups 85 and 86 batteries, with their most important features and specifications:

As one can see, dual-purpose group 85/86 batteries tend to be heavier than starting batteries due to the thicker lead plates which must support deep discharge use, but also must be able to provide strong enough currents for cranking internal combustion engines.

On the other hand, starting/cranking group 85/86 batteries are lighter since they are designed to produce strong current bursts for a very short period of time.

Also, since group 85/86 batteries are commonly used in passenger and similar cars as starting batteries, there are still many batteries with flooded/wet cells - although these batteries are not maintenance-free and spill-proof batteries, in areas with high(er) temperatures wet/flooded batteries may last longer than AGM/Gell-Cel batteries if they are maintained properly - if the electrolyte levels are checked periodically and if the distilled water is added when required.

And under the car's hoods, near the engines, it can become very hot.

Group 75 vs Group 86 Batteries

BCI Groups 75 and 86 are very similar in terms of dimensions:

- BCI Group 75: 9 1/16 x 7 1/16 x 7 11/16 (9.0625 x 7.0625 x 7.6875, 230 x 179 x 196 mm),

- BCI Group 86: 9 1/16 x 6 13/16 x 8 inches (9.0625 x 6.8125 x 8 inches, 230 x 173 x 203 mm).

Also, groups 75 and 86 have battery terminals on the same side - positive on the left, negative on the right.

As one can see, group 75 batteries are of the same length as group 86 batteries, but the group 86 batteries are somewhat narrower and taller - most battery compartments that accept group 86 batteries will also accept group 75 batteries.

However, just to be sure, check the documentation of the vehicle, if it can accept group 75 batteries.

The main difference between group 75 and group 86 batteries is in battery terminal types - group 75 batteries feature side battery terminals and group 86 batteries feature top battery terminals.

Thus, some battery brands offer batteries that are labeled as "75/86" batteries and feature both side and top battery terminals and in most cases can be used as a replacement for both BCI Group 75 and BCI Group 86 batteries.

Group 35 vs Group 86 Batteries

BCI Groups 35 batteries are another battery group that is very similar to the BCI Group 86 batteries in terms of dimensions:

- BCI Group 35: 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),

- BCI Group 86: 9 1/16 x 6 13/16 x 8 inches (9.0625 x 6.8125 x 8 inches, 230 x 173 x 203 mm).

As one can see, BCI Group 35 batteries are of the same length and almost the same width - group 35 batteries are just 2 mm wider.

However, BCI Group 35 batteries are almost an inch (7/8 inches, 22 mm) taller and thus have larger internal volume and better performances in terms of capacity, CCA/MCA, and RC. And yes, they tend to be somewhat heavier, but there are also some rather lightweight group 35 batteries with excellent performance.

The following comparison chart lists some of the most popular BCI Group 35 batteries:

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

It is quite common to replace group 86 battery with group 35 battery - after all, they have battery terminals on the same side.

However, this can be done only if the battery compartment can accept group 35 battery and if the new group 35 battery has the same or at least compatible hold-down edge.

Note: some cars come with tight fit battery compartments with mechanical and heat insulation and even forced cooling/ventilation of the battery compartment - for such cars it is highly recommended NOT to change the battery size.

The Best BCI Group 85/86 Battery

Personally, the best BCI group 85/86 battery is Odyssey 75/86-PC1230DT.

It is an AGM spill-proof, maintenance-free battery, designed as a dual-purpose battery that can withstand at least 400 cycles down to 80% DoD.

Also, it features a nominal capacity of 55Ah, RC value of 100 minutes, CCA value of 760 Amps, and MCA value of 815 Amps and as such can crank surprisingly large engines, diesel engines included.

Odyssey 75/86-PC1230DT can be easily recovered from deep discharges (which should be avoided!) and can operate at very low temperatures.

But, this battery is being phased out - it can still be found at some online shops and local stores, but ...

Why it is being phased out? Well, it is heavy and expensive and despite its excellent performances, it is simply an overkill for most users.

Because of that, Odyssey now offers a similar Odyssey ODP-AGM7586 battery, which is not as strong as Odyssey 75/86-PC1230DT, but it is nonetheless a rather robust and very reliable battery.

However, if You are looking for a car battery that will be used only as starting/cranking battery, other group 85/86 batteries are just as good as these batteries - just be sure that their CCA/MCA ratings are good enough for your vehicle.

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Long Story Short: BCI Groups 85/86 batteries are used as starting batteries in many passenger cars. Because of the similar dimensions, these batteries can be replaced with BCI Groups 75, 75/86 or even with group 35 batteries.

However, if possible, always use the battery group recommended by the vehicle's manufacturer - in this case, group 85 and/or 86:

Should You decide to replace the old group 85/86 battery with some other battery size (for example, with a group 35 battery), consider consulting yourself with the authorized dealership, just in case. And if the car is still within the warranty period, don't do anything - let them change the car's battery for You.

Whatever You do, it is your own responsibility.