BCI Group 4D, 6D, and 8D Batteries
BCI Group 4D, 6D, and 8D batteries are large and heavy, but also rather powerful batteries that are able to store large amounts of energy and are thus often used in high-demanding applications including off-the-grid systems, backup units for security and medical devices, electric carts and vehicles, as high-capacity electric trolling motor batteries, as RV house batteries, etc.
BCI Group 4D, 6D, and 8D batteries feature the same length, very similar height, but they differ in width. However, some manufacturers label their batteries as, for example, '4D' batteries although their batteries belong to '6D' batteries and similar. That is the reason one should always check the battery's actual size, not just the BCI battery group.
Updated: September 10, 2020.
Features and Specifications
Physical dimensions of BCI Group 4D, 6D, and 8D batteries differ and thus, their performances also differ. Physical dimensions are given in the following list:
- BCI Group 4D: 20.75 x 8.75 x 9.875 inches (527 x 222 x 250 mm),
- BCI Group 6D: 20.75 x 10 x 10.25 inches (527 x 254 x 260 mm),
- BCI Group 8D: 20.75 x 11.125 x 9.875 inches (527 x 283 x 250 mm).
The most popular BCI group of these groups is '4D' and then '8D'. BCI Group 6D is not very common, at least not officially, since it is rather hard to find battery labeled as '6D' battery.
But, very often batteries that are labeled as '4D' have physical dimensions (width!) that are very close to '6D', making them too large to be considered '4D' batteries.
The most popular 4D, 6D and 8D batteries are given in the following comparison chart:
|Model||Battery Type||Chemistry||Ah||CCA||MCA||RC||Weight (lbs/kg)||Dimensions
|AIMS Power LFP12V200A||Deep Cycle||LiFePO4||200 (2h)||-||-||~480||68.8 lbs; 31.1 kg||19.38 x 10.5 x 8.75||-|
|Concorde PVX-2580L||Deep Cycle||AGM||258||-||-||480 (@29.5 Amps)||159 lbs; 72.1 kg||20.76 x 10.22 x 9.77||-|
|Deka 8A4D||Deep Cycle||AGM||198||1110||-||380||129 lbs; 58.5 kg||20.75 x 8.5 x 10||-|
|Deka 8G4D||Deep Cycle||Gel||183||970||-||395||127 lbs; 57.6 kg||20.75 x 8.5 x 10||-|
|Deka 8A8D||Deep Cycle||AGM||245||1450||-||517||158 lbs; 71.6 kg||20.75 x 11 x 10||-|
|Deka 8G8D||Deep Cycle||Gel||225||1150||1470||500||157 lbs; 71.2 kg||20.75 x 11 x 10|
|ExpertPower EXP122000||Deep Cycle||AGM||220||-||-||600 (@20 Amps)||132.3 lbs; ~60 kg||20.59 x 9.44 x 8.62||-|
|Fullriver DC260-12||Deep Cycle||AGM||260||1525||1830||578||170.6 lbs; ~77 kg||20.51 x 10.59 x 8.82||-|
|GreenLiFE GL260||Deep Cycle||LiFePO4||260||-||-||624||80 lbs; 36.24 kg||20.44 x 10.57 x 8.7||-|
|LifeLine GPL-4DL||Deep Cycle||AGM||210||1100||1360||390||124 lbs; 56.2 kg||20.76 x 8.7 x 8.64||-|
|Lifeline GPL-8DL||Deep Cycle||AGM||255||1350||1675||550||156 lbs; 70.8 kg||20.76 x 10.89 x 9.65||-|
|Mighty Max ML4D||Deep Cycle||AGM||200||-||-||~360||114.6 lbs; ~52 kg||20.9 x 8.23 x 8.46||Mighty Max ML4D|
|Mighty Max ML8D||Deep Cycle||AGM||250||-||-||600 (@24.5 Amps)||159 lbs; 72.0 kg||20.47 x 10.55 x 8.66||-|
|NorthStar NSB-AGM8D||Dual Purpose||AGM||220||1450||1800||500||152 lbs; 68.9 kg||20.36 x 10.84 x 9.61||-|
|NorthStar SMS-AGM8DK||Dual Purpose||AGM||228||2250||2700||500||187 lbs; 84.7 kg||20.5 x 11.0 x 9.41||-|
|Odyssey 8D-1500||Deep Cycle||AGM||220||1500||1787||475||143 lbs; 64.8 kg||20.39 x 10.87 x 8.86||-|
|PowerStar PS200-12||Deep Cycle||AGM||200||-||-||-||135 lbs; 61.2 kg||20.55 x 9.37 x 8.58||-|
|Renogy RNG-BATT-AGM12-200||Deep Cycle||AGM||200||-||-||~600 (@20 Amps)||129 lbs; 58.5 kg||20.50 x 9.4 x 9.4||-|
|Renogy RNG-BATT-GEL12-200||Deep Cycle||Gel||200||-||-||~600 (@20 Amps)||128 lbs; ~ 58 kg||20.60 x 9.5 x 8.7||-|
|Renogy RBT200GEL12-G1||Deep Cycle||Gel||200||-||-||~600 (@20 Amps)||127.9 lbs; ~58 kg||20.6 x 9.4 x 8.8||Renogy RBT200GEL12-G1|
|Trojan 8D-AGM||Dual Purpose||AGM||230||1450||1850||460||161 lbs; 73 kg||20.47 x 10.64 x 9.08||-|
|Trojan 8D-Gel||Deep-Cycle||Gel||225||-||-||500||168 lbs; 76 kg||20.69 x 10.95 x 10.82||-|
|UPG UB4D-AGM||Deep Cycle||AGM||200||-||-||~600 (@20 Amps)||114.6 lbs; ~52 kg||21.0 x 8.15 x 8.47||-|
|UPG UB4D-Gel||Deep Cycle||Gel||180||-||-||300+||114.6 lbs; ~52 kg||20.87 x 8.11 x 8.43||-|
|UPG UB8D||Deep Cycle||AGM||250||-||-||600 (@23.2 Amps)||154 lbs; 70 kg||20.47 x 10.55 x 9.65||-|
|VMAXTANKS MB197-200||Deep Cycle||AGM||200||-||-||450||112 lbs; ~51 kg||19.1 x 6.8 x 9.5||-|
|VMAXTANKS MR197-200||Deep Cycle||AGM||200||-||1400||450||112 lbs; ~51 kg||19.1 x 6.8 x 9.5||-|
|VMAXTANKS XTR4D-200||Dual Purpose||AGM||200||1250||1670||470||130 lbs; ~59 kg||20.8 x 8.7 x 9.0||-|
|VMAXTANKS XTR8D-350||Deep Cycle||AGM||350||1700||2100||780||185 lbs; 83.8 kg||20.8 x 11.1 x 9.8||-|
|West Marine WM8A4D||Dual Purpose||AGM||198||1110||1420||380||131 lbs; 59.4 kg||20.75 x 8.5 x 10.0||-|
|West Marine WM8A8D||Dual Purpose||AGM||245||1450||1800||480||161 lbs; 73 kg||20.75 x 11 x 10.0||-|
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BCI Group 4D, 6D and 8D batteries are large batteries - even 'deep cycle' models are able to provide large starting currents, with 'official' 'dual-purpose' models having CCA ratings of 1500 and more Amps.
However, many models are designed exclusively for deep discharge cycle operations and should not be used as starting/cranking batteries, except for small internal combustion engines found on generators and similar, with starting currents of just a few hundred Amps.
Wet/Flooded vs. Gel vs. AGM vs. Lithium BCI Group 4D, 6D and 8D Batteries
Wet/flooded batteries are maintenance intensive batteries are rarely used these days. They can be found at shore/land permanent installations as part of large backup battery packs.
Gel batteries are spill-proof, maintenance-free batteries that often feature relatively small charging and discharging currents, but are able to withstand a large number of charging/discharging cycles. As such, Gel batteries are commonly used in off-the-grid applications charged by solar panels during the day, and providing power during the night.
AGM (Absorbent Glass Mat) batteries are also spill-proof, maintenance-free batteries that may be discharged and recharged with stronger currents than gel-cell batteries. As such, AGM batteries are often used as industrial batteries, vehicle batteries, UPS batteries, and similar.
Lithium batteries cost several times more than lead-acid batteries, but they are 2-4 times lighter and can withstand 10-15 times more charging/discharging cycles. Although their initial investment is larger, they are more cost-effective in the long run.
Note: when connecting wet/flooded, gel-cell, or AGM batteries in series and/or parallel, it is highly recommended to use not only the same batteries (size, capacity, chemistry), but the same batteries of the same manufacturer, from the same batch, in order to avoid imbalances. On the other hand, lithium-ion batteries feature BMS (Battery Management System) that monitors the battery and protects it from unwanted events (overcharging, over-discharging, short-circuit, etc.). Thus, every lithium battery features different BMS system and before even considering connecting them in parallel and/or series, check with their manufacturer if connection like that is supported.
How to Charge BCI 4D, 6D and 8D Batteries?
Due to their capacity, these batteries can be safely charged with 30 Amps chargers, with larger models being able to accept 50 Amps easily.
If the batteries are charged individually, the best practice is to have single, dedicated smart/intelligent battery charger/maintainer - such chargers support charging modes for flooded/wet cells, Gel-cells, AGM, and even lithium batteries.
The charging cycle of smart battery chargers starts with battery analysis, after which the battery charger starts with the charging process according to the current battery condition and ends with cell equalization mode and with maintenance mode.
Solar panels and wind turbines should be connected to MPPT charge controller, ensuring proper charging even when the sun and wind conditions are far from ideal.
In single battery marine and automotive systems (boats, cars, trucks, RVs, etc.) where 4D, 6D and 8D batteries are used as both deep discharge and starting batteries, the battery should be recharged via an onboard alternator and its control electronics.
Note: in single battery systems, there is always a danger of discharging the battery too low in order for the battery to crank the main engine safely. Personally, if you have such a system, don't discharge your battery below 50% DoD and if possible, always have lithium jump-starter fully charged and ready to be used ...
In two battery marine and automotive systems (boats, cars, trucks, RVs, etc.) where 4D, 6D and 8D batteries are used only as deep discharge batteries, the battery should be recharged via an onboard alternator and its control electronics.
Some boats and vehicles have a central MPPT charge controller with connectors for an alternator, solar panels, and wind turbines (as input) and the battery connectors (as output).
BCI Group 4D, 6D and 8D Batteries As Trolling Motor Batteries
BCI Group 4D, 6D and 8D batteries are excellent electric trolling motor batteries, except one thing - their weight.
The maximum current of modern trolling motors is limited to 60 Amps per battery at full throttle. Most of the BCI Group 4D, 6D and 8D batteries are able to provide 60 Amps for at least 2h 30min.
When the electric trolling motor is throttled down, on average its current drops to half, or even less than half.
Most of the BCI Group 4D, 6D and 8D batteries feature Reserve Capacity (25 Amps) of at least 300 minutes (5 hours), with some models (like VMAXTANKS XTR8D-350) featuring RC value of 780 minutes (13 hours!).
However, AGM and Gel-cell batteries are heavy - if your boat is large enough to accept a battery (or batteries) of this size, then place it low in the boat (below the waterline) and it will even increase the boat's stability.
For applications where such a weight penalty is simply unacceptable, lithium batteries are the way to go - lithium batteries initially cost more, but they don't lose capacity as much as lead-acid batteries when the discharging currents are increased, they are 2-4x lighter and can withstand 10-15x more charging/discharging cycles.
Note: lithium batteries should be recharged as recommended by their manufacturer - most models can safely be recharged with advanced AGM battery chargers using charging mode specifically intended for lithium batteries.
BCI Group 24 vs BCI Group 8D
BCI Group 24 is a very popular group of automotive, industrial, and marine batteries, with physical dimensions (L x W x H) of 10.25 x 6.8125 x 8.875 inches (260 x 173 x 225 mm).
BCI Group 8D physical dimensions (L x W x H) are 20.75 x 11.125 x 9.875 inches (527 x 283 x 250 mm), allowing three BCI Group 24 batteries to fit into the battery compartment intended for Group 8D battery.
Since group 24 batteries also feature starting batteries, such a battery pack of 3 starting or 3 dual-purpose batteries may have excellent cranking/starting characteristics.
NorthStar Battery even manufactures a battery pack like that one: NorthStar SMS-AGM8DK battery, which consists of three group 24 batteries and is delivered as a disassembled battery pack, allowing the user to assemble the battery pack directly in the battery compartment, which can be very helpful when replacing the battery in tight areas.
NorthStar SMS-AGM8DK battery is the heaviest battery in our comparison chart, and it is even heavier than VMAXTANKS XTR8D-350 battery (187 vs 185 pounds).
But, NorthStar SMS-AGM8DK battery features internal resistance of only 1.5 mΩ, 2250 CCA Amps, 2700 MCA Amps, 3125 PHCA Amps (seconds?), and 228 Ah 20h capacity.
Also, it comes with a 3 year warranty.
NorthStar SMS-AGM8DK battery is anything but cheap battery - for industrial and similar applications requiring a premium battery, it simply outperforms all other batteries.
Long Story Short: BCI Group 4D, 6D and 8D batteries store large amounts of energy and are used everywhere where that energy is required.
Before getting a new battery, always check the actual battery compartment size and the battery size - better safe than sorry.
Which BCI Group 4D, 6D and 8D battery is the best one? Well, batteries should be chosen according to the individual needs and requirements, but also budget.
Whatever you do, stay safe - these are large units and if misused (short circuit, for example), they can make a lot of damage and even injure (or worse) people, kids, pets ...