Optima Batteries D27M BlueTop and D27F YellowTop Starting and Deep Cycle Batteries

Optima Batteries D27M BlueTop and D27F YellowTop Starting and Deep Cycle Batteries are versatile, dual purpose marine and automotive batteries. Optima Batteries D27M BlueTop and D27F YellowTop are AGM (Absorbent Glass Mat) SLA (Sealed Lead Acid) batteries, with the spiral wound lead plates, offering good vibration resistance, extended life, low maintenance and faster recharging.

Optima Batteries D27M BlueTop and D27F YellowTop are completely spill proof 12V AGM batteries, mountable in virtually any position.

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Optima Batteries D27M BlueTop and D27F YellowTop - Features and Specifications

Optima Batteries D27M BlueTop and D27F YellowTop are BCI Group 27 batteries. Their nominal capacity is 66 Ah (20h capacity), with reserve capacity (RC) of 140 minutes.

However, they also differ in few important details. Optima Batteries D27M BlueTop is dual purpose battery intended for marine applications and D27F YellowTop is dual purpose battery intended for automotive applications. Their specifications are given in the following table:

Model Optima Batteries D27M BlueTop Optima Batteries D27F YellowTop
BCI Group 27 27
Weight 53.8 lbs (~24.4 kg) 53.2 lbs (~24.1 kg)
20h Capacity 66 Ah 66 Ah
 Post Type Dual SAE & 5/16 Stainless Stud  SAE Post
CCA 800 Amps  830 Amps
MCA 1000 Amps 1025 Amps
Dimensions (L x W x H) 12.19 x 6.81 x 8.75 inches
31 x 17.3 x 22.2 cm
12.16 x 6.76 x 8.61 inches
30.9 x 17.2 x 21.9 cm
Reserve Capacity (25A) 140 minutes 140 minutes
 Internal Resistance 2.5 mΩ 2.5 mΩ 
Amazon Link Optima Batteries D27M BlueTop Optima Batterues D27F YellowTop

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

As one can see, Optima D27F YellowTop batttery is slightly lighter battery, features 'only' SAE posts and is capable of providing slightly more CCA and MCA.

Nominal capacity and reserve capacities of these two batteries are the same - 66 Ah and 140 minutes.

Since these are dual purpose batteries, they provide less cranking amps than true starting batteries and feature shorter RC than true deep cycle batteries.

However, they provide much more cranking amps than deep cycle batteries and feature longer RC than starting batteries.

Also, they tolerate 300+ discharge/recharge cycles, especially when charged with Optima Digital chargers.

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Optima Batteries D27M BlueTop and D27F YellowTop are intended for marine and automotive applications where they can be used as starting batteries and at the same time are able to provide power for electric and electronic devices like lights, onboard computers, GPS units, alarms and similar.

With boats, yachts, cars, trucks and similar vehicles having so much electronic devices that are slowly draining main battery while the main engine is turned off, having a good and reliable dual purpose battery is more and more important.

If your boat or vehicle has a dual battery system (one dedicated starting battery, another battery or battery pack as dedicated deep cycle battery), then consider getting batteries that are optimized for such purpose.

Optima Batteries D27M BlueTop and D27F YellowTop As Trolling Batteries

Optima Batteries D27M BlueTop and D27F YellowTop are very good choice as electric trolling motor battery for smaller electric motors.

Both batteries are able to provide 25 Amps for 140 minutes (2 hours and 20 minutes) - that is 58.33 Ah effectively, which is good result for 66 Ah batteries.

However, stronger motors requiring 50 Amps or more drain these batteries too fast and getting larger, deep cycle battery (or batteries) for such applications is recommended.

 Optima Batteries D27M BlueTop and D27F YellowTop As Fish Finder Batteries

Most onboard fish finders require less than 2 Amps when operating at full power. Since both D27M and D27F can provide 2 Amps for 33+ hours easily, they are very good choice as fish finder batteries for situations where main boat engine is going to be offline for hours.

And if the boat has solar panels and wind turbine installed, such setup can power fish finder, navigational lights and few more devices practically indefinitely.

 Optima Batteries D27M BlueTop and D27F YellowTop As Starting Batteries

Optima Batteries D27M BlueTop can provide 800 CCA and 1000 MCA, while Optima Batteries D27F YellowTop can provide slightly more amps: 830 CCA and 1025 MCA.

Both batteries are practically the same internally (spiral wound cells), but they have different posts and thus internal connections are somewhat different.

Either way, both batteries can provide strong currents that can start large internal combustion engines, even at low temperatures.

How to Charge Optima Batteries D27M BlueTop and D27F YellowTop

When they are mounted in the boat or vehicle, these batteries are charged like any other boat/vehicle lead-acid battery via onboard generator/alternator powered by the main engine or using solar panels/wind turbine chargers/controllers.

When being charged via mains power, both D27M and D27F batteries can be charged using ordinary lead-acid battery chargers, preferably chargers designed for AGM batteries.

optima digital 400 12v charger

The best results are obtained using Optima Digital 400 and 1200 intelligent AGM chargers that first test the battery condition and then charge the batteries in several steps.

Also, these chargers employ simple, single button controls, allowing the users to charge different types of batteries in optimal way.

The most important difference between these chargers is the maximum charging current - Optima Digital 400 charger features 4 Amps max. charging current, while Optima Digital 1200 charger features 12 Amps max. charging current.

For more information about these chargers, please check Optima Digital 400 12V Performance Maintainer and Battery Charger and Optima Digital 1200 12V Performance Battery Charger and Maintainer Amazon links (links open in the new windows).


optima d27 m f mLong Story Short: Optima Batteries D27M BlueTop and D27F YellowTop are versatile and durable, dual purpose batteries. They are excellent choice for single-battery electric systems commonly found in cars and boats and for outdoors applications where type of load is not always known in advance.

Also, Optima Batteries D27M BlueTop and D27F YellowTop come with 2 year limited warranty.

Note that there are cheaper batteries in this class, but what you pay is what you get - Optima batteries are very popular batteries that will not let the user down, if and when used for what are they designed to.

For more reviews and recommendations, check Optima Batteries D27M BlueTop and Optima Batteries D27F YellowTop Amazon links (links open in the new windows).