Dual Battery

[JackyCam]

Hi all!

I came across such a thing as dual-use batteries, they say, with the help of it, you can start the motor and power the electronics, now I'm thinking about replacing my starting battery and I'm very interested in these doubles, maybe someone uses it would like to get feedback!

[Bamaskeet]

I have no problems using standard AGM batteries for cranking.  I have three group 31 AGM batteries on my boat.  Two for the trolling motor and one cranking battery.

[wthree3]

Dual purpose batteries are designed to be a compromise between deep cycle and cranking. Good choice when using a single battery for starting and house loads. Something to consider next time you are shopping for a battery. 

[jh141]

15 hours ago, JackyCam said:

Hi all!

I came across such a thing as dual-use batteries, they say, with the help of it, you can start the motor and power the electronics, now I'm thinking about replacing my starting battery and I'm very interested in these doubles, maybe someone uses it would like to get feedback!

So A pure lead AGM battery is considered a Dual Purpose, example, my optima blue top group 27 is pure lead ( no alloy mixed in ) and that increases the CCA to meet cranking needs. Not all AGMs are non alloy, but by moving up in group size lets say from 24 to 31 you also greatly increase the cranking capacity.

Dual Purpose are more expensive but are so called better built and last longer. Thought I have one I am not convinced. I have three Deka group 24s (not considered Dual Purpose) for my 36 volt trolling circuit and one Optima Group 27. The Optima is my main cranking and accessory battery but when I had a cable failure to the Optima and switched to battery 2 which is one of the Deka Group 24s It did just as good a job cranking my Yamaha and running everything all day. 

Oh I guess I should also say I have a Stealth 1 AC/DC charging system.

Bottom line....A good AGM group sized big enough to meet the CCA needs is most economical and long lasting. 

Well then there is Lithium but their not Economical.

[JackyCam]

On 2/23/2021 at 6:36 PM, jh141 said:

So A pure lead AGM battery is considered a Dual Purpose, example, my optima blue top group 27 is pure lead ( no alloy mixed in ) and that increases the CCA to meet cranking needs. Not all AGMs are non alloy, but by moving up in group size lets say from 24 to 31 you also greatly increase the cranking capacity.

Dual Purpose are more expensive but are so called better built and last longer. Thought I have one I am not convinced. I have three Deka group 24s (not considered Dual Purpose) for my 36 volt trolling circuit and one Optima Group 27. The Optima is my main cranking and accessory battery but when I had a cable failure to the Optima and switched to battery 2 which is one of the Deka Group 24s It did just as good a job cranking my Yamaha and running everything all day. 

Oh I guess I should also say I have a Stealth 1 AC/DC charging system.

Bottom line....A good AGM group sized big enough to meet the CCA needs is most economical and long lasting. 

Well then there is Lithium but their not Economical.

Thank u very much for such a detailed answer!

[JackyCam]

On 2/23/2021 at 7:38 AM, wthree3 said:

Dual purpose batteries are designed to be a compromise between deep cycle and cranking. Good choice when using a single battery for starting and house loads. Something to consider next time you are shopping for a battery. 

Thank you, I will definitely consider it!

[jack f]

Currently using three AGM optima blue top 31's. Previously used three duracell AGM 31's. I really like the AGM's & was happy with both versions, probably overkill.