Deep Cycle Marine Battery

Best BCI Group 65 Batteries

BCI Group 65 batteries are mid-range automotive and light industry batteries, often used in marine applications as starting/cranking batteries and as deep-cycle/dual-purpose batteries in both single- and dual-battery systems.

The most popular BCI Group 65 battery type is a lead-acid AGM battery, although lithium batteries are becoming more and more popular as well.

northstar nsb agm65

BCI Group 65 Batteries Features and Specifications

BCI Group 65 batteries feature maximum physical dimensions of (L x W x H) 12 1/16 x 7 1/2 x 7 9/16 inches (12.0625 x 7.5 x 7.5625 inches, 306 x 190 x 192 mm), with a typical weight of the lead-acid Absorbent Glass Mat (AGM) group 65 battery in the 42.5 to 58 pounds (19.3 to 26.3 kg) range.

The actual battery size may be somewhat larger than the standard size, especially the height with the terminals, so before buying any new battery (not just group 65 battery), check the battery compartment size and the size of the battery.

Nominal 20h capacity of the AGM Group 65 batteries vary between 69 and 75 Ah, CCA between 750 and 950 Amps, MCA between 900 and 1070 Amps, and Reserve Capacity between 120 and 150 minutes.

The following BCI Group 65 batteries cross-reference chart lists some of the most popular group 65 batteries, with their features and specifications:

Model Battery Type Cell Type Ah CCA MCA RC Weight (lbs/kg)
ACDelco 65AGM Dual Purpose AGM 70 750 900 120 42.5 lbs; 19.3 kg
Deka 9A65 AGM Dual Purpose AGM 75 776 950 150 47.5 lbs; 21.5 kg
Delphi BU9065 MaxStart Dual Purpose AGM 75 750 - 150 47.5 lbs; 21.5 kg
Full Throttle FT930-65 Dual Purpose AGM 75 930 1070 150 57.5 lbs; 26.1 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 58 lbs; 26.3 kg
Renogy Li 12V 100Ah Deep Cycle LiFePO4 100 - - ~230 26 lbs; 11.8 kg
XS Power D6500 XS Series Dual Purpose AGM 75 - 1070 150 58.3 lbs; 26.4 kg

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

As one can see, all AGM batteries are labeled as dual-purpose batteries - batteries are large enough to be able to crank even larger gas and diesel engines, and thanks to the AGM technology, they also tolerate deep discharge cycle applications. xs power d6500

Most AGM batteries are of spill-proof design and may operate in any position, except perhaps up-side-down. This depends on the battery model and internal battery design.

Best AGM Group 65 Battery?

There are several group 65 batteries that offer very similar performances, at least in theory. These batteries are Full Throttle, NorthStar, Odyssey, and XS group 65 batteries.

Having taken into account details like price, low-temperature performances, self-discharge rate, cranking and deep-cycle features, reliability, robustness, etc. one may freely conclude that the best group 65 AGM battery performer is the Odyssey 65-PC1750T battery.

odyssey 65 pc1750t

Odyssey 65-PC1750T battery feature nominal 20h capacity of 74 Ah, Cold Cranking Amps rating of 950 Amps, Marine Cranking Amps rating of 1070 Amps, Reserve Capacity of 145 minutes and it weighs 'respectable' 58 pounds (26.3 kg).

Note: 'respectable' - it is far from being the lightest battery in this group, on a contrary, only XS Power D6500 is somewhat heavier than the Odyssey 65-PC1750T (58 vs 58.3 pounds).

As a deep cycle battery, the Odyssey 65-PC1750T battery is able to withstand ~400 cycles down to 80% DoD.

Odyssey 65-PC1750T battery cannot freeze down to -40˘F (-40°C), so it can be left in the vehicle even during the winter. Also, it features a very low self-discharge rate - when stored at room temperature, it should be recharged in 18-24 months (when the voltage drops below 12V).

 Lithium BCI Group 65 Battery

A typical example of the lithium BCI Group 65 battery is the ultralight Renogy RBT100LFP12S-G1 battery based on the Lithium Iron Phosphate (LiFePO4) chemistry.

renogy group65 lithium battery

Renogy RBT100LFP12S-G1 battery features a nominal voltage of 12.8 volts and nominal (0.2C - 20 Amps) capacity of 100 Ah.

Physical dimensions of the Renogy RBT100LFP12S-G1 battery are (L x W x H) 11.4 x 6.8 x 7.4 inches (289 x 172 x 187.5 mm), and it weighs 26 pounds (11.8 kg), which is ~2x less than the typical group 65 AGM battery.

When discharged at 20 Amps rate (0.2C) Renogy RBT100LFP12S-G1 is able to withstand ~4000 charging/discharging cycles down to 80% DoD, or ~7000 charging/discharging cycles down to 50% DoD.

Although it initially costs more than AGM batteries, in the long run, Renogy RBT100LFP12S-G1 is actually cheaper.

The maximum continuous discharge current is 100 Amps, with a maximum 60 seconds current of 130 Amps.

Renogy RBT100LFP12S-G1 features an intelligent Battery Management System (BMS) which protects the battery from unwanted events, like overcharge, over-discharge, over-voltage, over-current, and similar.

Renogy RBT100LFP12S-G1 features a maximum charging current of 50 Amps, ensuring that the battery can be recharged rather quickly.

Obviously, Renogy RBT100LFP12S-G1 is an excellent deep-cycle performer (current less than 100 Amps), that should not be used as a cranking/starting battery - BMS cuts off battery @150 Amps load!

How to Charge Group 65 Batteries

AGM group 65 batteries mounted in the vehicles should be recharged via onboard alternators and control electronics - if possible, set the charging mode to 'AGM' battery.

Other AGM group 65 batteries should be recharged using intelligent AGM battery chargers with the maximum charging current around 15 Amps - modern AGM group 65 batteries may accept even stronger currents, but 15 Amps AGM battery charger my fully recharge Odyssey 65-PC1750T battery discharged down to 80% DoD in slightly more than 4 hours.

On the other hand, lithium batteries should be recharged either using dedicated lithium battery chargers or using smart AGM battery chargers that come with the dedicated lithium battery charging mode.

Generally, lithium batteries accept charge even faster than AGM batteries - Renogy RBT100LFP12S-G1 may be recharged at a 50 Amps rate.

Thus, using any smart lithium battery charger in the 15-40 Amps range can recharge such battery properly.

Note: Lithium battery chargers charge the batteries using the Constant Current/Constant Voltage (CC/CV) algorithm that differs significantly from the AGM battery charging algorithm/process.

Group 65 Batteries as a Trolling Motor Batteries

newport vessels kayak 55lbs 24inch mGroup 65 AGM batteries may be used as trolling motor batteries, thanks to their ability to provide required currents (50-60 Amps max) and their ability to withstand deep-cycle use.

When being pushed to the limit, Group 65 Batteries are able to provide 50 Amps up to 45-60 minutes (depending on the battery model, battery condition, temperature, and similar), and up to 120-150 minutes at a 25A rate.

On the other hand, lithium batteries don't feature a sharp drop in capacity when being discharged with stronger currents, like AGM batteries do.

Renogy RBT100LFT12S-G1 battery is able to provide 25 Amps up to 220-230 minutes and 50 Amps for at least 100-110 minutes - again, depending on the battery condition, temperature, and similar.

As a trolling motor battery and as a deep-cycle low-current (<100 Amps) battery, the Renogy RBT100LFT12S-G1 battery is a much better performer than the AGM group 65 batteries.

And it costs much more, at least initially - in the long run, with its extra-large number of charging/discharging cycles, Renogy RBT100LFT12S-G1 battery is actually a cheaper battery, especially considering stored and delivered energy per cycle.


Long Story Short: BCI Group 65 batteries are very popular automotive and light industrial batteries that may be also used as trolling motor batteries, at least dual-purpose models:

Model Battery Type Cell Type Ah CCA MCA RC Weight (lbs/kg)
ACDelco 65AGM Dual Purpose AGM 70 750 900 120 42.5 lbs; 19.3 kg
Deka 9A65 AGM Dual Purpose AGM 75 776 950 150 47.5 lbs; 21.5 kg
Delphi BU9065 MaxStart Dual Purpose AGM 75 750 - 150 47.5 lbs; 21.5 kg
Full Throttle FT930-65 Dual Purpose AGM 75 930 1070 150 57.5 lbs; 26.1 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 58 lbs; 26.3 kg
Renogy Li 12V 100Ah Deep Cycle LiFePO4 100 - - ~230 26 lbs; 11.8 kg
XS Power D6500 XS Series Dual Purpose AGM 75 - 1070 150 58.3 lbs; 26.4 kg

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

However, if You are looking for a lightweight group 65 battery that cycles a lot, consider the Renogy RBT100LFT12S-G1 battery, it may surprise You with its performance.

Just be sure to charge lithium batteries with lithium battery chargers.



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