Best BCI Group 34 Battery

BCI Group 34 Batteries are very popular car, boat, and light industry batteries, used in deep-cycle, dual-purpose, and starting/cranking applications.

Most modern group 34 batteries are Sealed Lead-Acid (SLA) Absorbent Glass Mat (AGM) batteries, but flooded batteries are still present. Also, lithium group 34 batteries are becoming more common. But, group 34 AGM batteries are still going on strong, offering a strong and reliable source of electric power at an acceptable price.

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BCI Group 34 Features, Specifications, and Dimensions

BCI Group 34 batteries are very similar in size with groups 24, 35, and 78 - in fact, some manufacturers offer batteries labeled as '34/78'.

Battery sizes for these groups are given in the following list:

- Group 24: 10.25 x 6.8125 x 8.875 inches (260 x 173 x 225 mm),

- Group 34: 10.25 x 6.8125 x 7.875 inches (260 x 173 x 200 mm),

- Group 35: 9.0625 x 6.875 x 8.875 inches (230 x 175 x 225 mm),

- Group 78: 10.25 x 7.0625 x 7.6875 inches (260 x 179 x 196 mm).

Note: BCI Group 24 features several sub-models - for more about these batteries, feel free to check our BCI Group 24 Batteries article.

As one can see, group 34 batteries may easily fit battery compartments intended for group 24 batteries, while group 78 batteries are slightly wider (due to side terminals) and a little bit lower. Similarly, group 35 batteries are a little bit shorter, but wider and taller, with minimal differences.

Note: whenever replacing any battery, not only group 34 batteries, it is highly recommended to check the size of the battery compartment and actual size of the battery.

Depending on the intended use, group 34 batteries may be:

- 'classic' group 34 batteries: positive terminal post on the left side of the battery,

- group 34R battery: positive terminal post on the right side of the battery,

- group 34/78 battery: battery features both SAE and side battery terminal posts,

- group 34M battery: battery features both SAE and Marine battery terminal posts.

Note that batteries may feature different types of terminal posts, with some models featuring even several sub-models.

optima group 34 batteries

The following chart lists some of the most popular AGM, flooded and lithium, starting/cranking, dual-purpose and deep cycle, group 34, 34R, and 34/78 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 LFP-34M Lithium Dual Purpose LiFePO4 50 800 - ~120 13.8 lbs; 6.25 kg -
Banshee 34M AGM Dual Purpose Enhanced Flooded 66 750 870 100 37.0 lbs; 16.8 kg -
Deka 9A34 Dual Purpose AGM 55 750 955 120 41 lbs; 18.6 kg -
Delphi BU9034 MaxStart Starting AGM 55 775 - 120 42.5 lbs; 19.3 kg -
DieHard 38232 Starting AGM 55 775 - 120 44.5 lbs; 20.2 kg -
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 -
NorthStar NSB-AGM34/78 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 Odyssey 34M-PC1500
Odyssey 34R-PC1500T Dual Purpose AGM 68 850 1050 135 49.5 lbs; 22.4 kg
Odyssey 34/78-PC1500DT Dual Purpose AGM 68 850 1050 135 49.5 lbs; 22.4 kg
Optima 8002-002 34 RedTop Starting AGM 50 800 1000 100 37.9 lbs; 17.2 kg -
Optima 8003-151 34R RedTop Starting AGM 50 800 1000 100 37.9 lbs; 17.2 kg -
Optima 8004-003 34/78 RedTop Starting AGM 50 800 1000 100 38.8 lbs; 17.6 kg -
Optima 8006-006 34M BlueTop Starting AGM 50 800 1000 100 38.40; 17.4 kg Optima 34M BlueTop
Optima 8016-103 D34M BlueTop Dual Purpose AGM 55 750 870 120 43.5 lbs; 19.7 kg Optima D34M BlueTop
Optima 8012-021 D34 YellowTop Dual Purpose AGM 55 750 870 120 42.9 lbs; 19.5 kg -
Optima 8014-045 D34/78 YellowTop Dual Purpose AGM 55 750 870 120 43.5 lbs; 19.7 kg -
VMAXTANKS XTR34-75 Deep Cycle AGM 75 - - 145 45.0 lbs; 20.4 kg -
XS Power D3400 Dual Purpose AGM 65 - 1000 135 48.0 lbs; 21.8 kg -
XS Power D3400R Dual Purpose AGM 65 - 1000 135 48.0 lbs; 21.8 kg -

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.

BCI Group 34 batteries generally can be categorized as starting/cranking, dual-purpose, and deep-cycle batteries.

Starting Group 34 Batteries

Starting group 34 batteries are mostly AGM lead-acid batteries with CCA value around 775-800 Amps, MCA value around 1000 Amps, Reserve Capacity 100-120 minutes, and average weight of 38-45 pounds (~17.2 - 20.4 kg).

As starting batteries, these batteries are optimized for providing strong currents for short periods of time and should not be used in deep discharge applications, although AGM lead-acid batteries, even if designed as starting batteries, do tolerate a relatively large number of charging/discharging cycles.

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Flooded group 34 batteries are not as common as they once were, but Enhanced Flooded lead-acid batteries feature better electrolyte mixing than AGM batteries and often perform better in Start&Stop vehicle applications.

Personally, for high-demanding Start&Stop application go for maintenance-free high-quality AGM lead-acid battery and don't worry about terminals/cables corrosion (at least not as much as with flooded batteries), about checking the amount of electrolyte and similar.

Dual-Purpose Group 34 Batteries

Dual-purpose group 34 batteries are almost exclusively AGM lead-acid batteries, although Lithium Iron Phosphate (LiFePO4) batteries are slowly appearing on the market.

Dual-purpose group 34 batteries feature CCA values between 750 and 880 Amps, MCA values between 870 and 1050 Amps, Reserve Capacities between 100 and 135 minutes and they weigh up to 51 pounds (~23.1 kg).

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Due to the thicker plates, dual-purpose batteries are heavier than starting batteries, but they can both provide strong starting currents and they cycle reasonably well - much better than the starting batteries.

Due to their versatility, dual-purpose batteries tend to cost more than the starting batteries.

But, if You are looking for an all-around battery for your vehicle, boat, or for some light industrial application for powering various loads, dual-purpose batteries are the way to go.

Deep-Cycle Group 34 Batteries

Deep cycle group 34 batteries are not as common as starting and dual-purpose group 34 batteries because slightly larger BCI group 24 batteries offer capacities of ~75 Ah.

But, VMAXTANKS XTR34-75 features a nominal capacity of 75 Ah, a Reserve Capacity of 145 minutes and it weighs a very acceptable 45 pounds (~20.4 kg). Although deep cycle battery, VMAXTANKS XTR34-75 has HCA (Hot Cranking Amps - measured at 77°F, 25°C) value of 1100 Amps.

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But, it is designed to be used for deep cycle applications like trolling motor battery, off-the-grid (solar, wind) battery, power inverter battery, in electric vehicles, in wheelchairs, and similar.

How to Charge Group 34 Batteries

When group 34 batteries are used in vehicles and boats that feature internal combustion engine(s) with an alternator (electric generator), let this built-in system to charge the battery.

When these and similar batteries are charged using battery chargers, be sure to use smart battery chargers optimized for charging different battery types (flooded, AGM, Gel-Cell) with the charging currents in the 10-15 Amps range.

Also, if you happen to have a lithium battery, be sure to use a battery charger intended for lithium batteries or a smart AGM battery charger that features a dedicated charging mode for lithium batteries.

For example, a 70Ah battery discharged down to 50% DoD (35 Ah required) can be fully recharged in under 4 hours using a 10 Ah smart battery charger.

Smart battery chargers analyze the battery and adjust the charging process according to the battery's condition - if required, they will use desulphation, equalization, and other available charging modes to recover deeply discharged batteries and to equalize the battery cells in order to prolong the battery's operating life.

And when the battery is fully charged, they will switch to the maintenance mode, maintaining the battery fully charged.

Group 34 Batteries as Power Inverter/Off-the-Grid Batteries

Dual-purpose and especially deep-cycle batteries can be used as medium-large power inverter batteries in various off-the-grid situations, like camping, fishing trips, in emergencies, and similar.

For example, if 12V 65-75 Ah battery is used to power a 500W power inverter with 85% efficiency, then that battery must provide:

P(W) = 500W / 0.85 = ~590 W → ~50 Amps

'Problem' with the lead-acid batteries is a significant drop in capacity when they are being discharged with strong currents. Typically, when the lead-acid battery is being discharged for one hour, the actual capacity drops down to ~55 - 72% of the nominal (20h) capacity.

That means that in this case, 12V 65-75 Ah battery can provide power approximately for 40-60 minutes when powering a 500W power inverter with 85% efficiency at full power.

The exact time depends on the battery - check constant power and constant current discharge charts (if provided by the battery manufacturer) and extrapolate the expected runtime of your battery in this example.

Note: If the power inverter is constantly loaded at 100% of its nominal power, it is an underpowered unit and should be replaced as soon as possible with the stronger unit (and probably battery/batteries).

 


Long Story Short: BCI Group 34 batteries are versatile units and rather reliable sources of power, especially AGM batteries that are being used by countless users in real-life applications.

When looking for a new battery, pick the right size, battery type, chemistry, and terminal type, and orientation.

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 LFP-34M Lithium Dual Purpose LiFePO4 50 800 - ~120 13.8 lbs; 6.25 kg -
Banshee 34M AGM Dual Purpose Enhanced Flooded 66 750 870 100 37.0 lbs; 16.8 kg -
Deka 9A34 Dual Purpose AGM 55 750 955 120 41 lbs; 18.6 kg -
Delphi BU9034 MaxStart Starting AGM 55 775 - 120 42.5 lbs; 19.3 kg -
DieHard 38232 Starting AGM 55 775 - 120 44.5 lbs; 20.2 kg -
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 -
NorthStar NSB-AGM34/78 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 Odyssey 34M-PC1500
Odyssey 34R-PC1500T Dual Purpose AGM 68 850 1050 135 49.5 lbs; 22.4 kg
Odyssey 34/78-PC1500DT Dual Purpose AGM 68 850 1050 135 49.5 lbs; 22.4 kg
Optima 8002-002 34 RedTop Starting AGM 50 800 1000 100 37.9 lbs; 17.2 kg -
Optima 8003-151 34R RedTop Starting AGM 50 800 1000 100 37.9 lbs; 17.2 kg -
Optima 8004-003 34/78 RedTop Starting AGM 50 800 1000 100 38.8 lbs; 17.6 kg -
Optima 8006-006 34M BlueTop Starting AGM 50 800 1000 100 38.40; 17.4 kg Optima 34M BlueTop
Optima 8016-103 D34M BlueTop Dual Purpose AGM 55 750 870 120 43.5 lbs; 19.7 kg Optima D34M BlueTop
Optima 8012-021 D34 YellowTop Dual Purpose AGM 55 750 870 120 42.9 lbs; 19.5 kg -
Optima 8014-045 D34/78 YellowTop Dual Purpose AGM 55 750 870 120 43.5 lbs; 19.7 kg -
VMAXTANKS XTR34-75 Deep Cycle AGM 75 - - 145 45.0 lbs; 20.4 kg -
XS Power D3400 Dual Purpose AGM 65 - 1000 135 48.0 lbs; 21.8 kg -
XS Power D3400R Dual Purpose AGM 65 - 1000 135 48.0 lbs; 21.8 kg -

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.

In the end, choose according to your own needs and personal requirements.