Batteries??

[Jack]

Hi All,

So after 8 good years it's time to replace my Deka Dual Purpose group 27. We have a separate start batt (wet so we will be staying with that) so this is just for the house.
Q - Do the deep cycle batts really not have the cranking amps to start the engine in an emergency?
Q - Which batts are your favorites? (brand - dual or deep - group)

Thanks,

J&R

 

[Don S/V ILLusion]

This is a subjective question and there are lots of 'right' answers.

Not knowing your power needs such as refrigeration, cruising pattern away from dock power to recharge, etc..., it's impossible to provide logical reasons for type/sizing of a battery bank.

Having said that, one good option is to trash the so-called 'dual purpose' battery for a pair of 6v deep cycle batteries which will give you lots more capacity and easily start a small diesel.

 

[Jack]

Thanks Don,

That's a good idea...
Our power needs are fair, we have a fridge but are very conscious of the power it will consume. We would like to not have to worry about using the navigation electronics (W,S,D plus an MFD) while sailing long distances, etc...
We have a 29hp Yanmar for an engine with a 60amp alternator.
We swing on a mooring this season but may be on shore power next, but i don't want that to influence our batt choice too much.

That said, i believe using 6v batts means combining the batts in series (pos to neg to pos to neg) rather than parallel. Is that correct?

J&R

 

[Terry Cox]

Hi Jack, our previous boat, an H28, came with two group 27 deep cycle wet batteries. I made it a practice to alternate one of them on an odd day for purposes of operating the boat leaving the other, unused, with a full charge. Then when back on shore power switch back to both. Each had enough power to start our 2GM with ease.

I've always had good results with the Interstate brand. If you have a nearby Interstate distributor, ask them face-to-face for a better price rather than purchasing from a retailer. That will save you some $$. Some prefer 6V, but 12V works for our needs.

 

[Don S/V ILLusion]

Thanks Don,

That's a good idea...
Our power needs are fair, we have a fridge but are very conscious of the power it will consume. We would like to not have to worry about using the navigation electronics (W,S,D plus an MFD) while sailing long distances, etc...
We have a 29hp Yanmar for an engine with a 60amp alternator.
We swing on a mooring this season but may be on shore power next, but i don't want that to influence our batt choice too much.

That said, i believe using 6v batts means combining the batts in series (pos to neg to pos to neg) rather than parallel. Is that correct?

J&R

thats correct. The conventional wisdom is the size your battery cap and alternator according to need but your past success indicates you are good with your current system so adding a bit more capacity with 2x 6v batteries can only help.
Terry's alternative is also a good option.

 

[Stu Jackson]

Deep cycle batteries easily start our engines (those small diesels in our recreational boats). Maine Sail & I have been saying this for decades.

http://www.pbase.com/mainecruising/boat_projects

Noodle around there if you haven't already.

 

[sesmith]

Yes on your first question...no problem. I swapped my group 27 house battery for 2 x 6v Duracell branded EGC2 batteries last winter. According to what I read, the 2 EGC2 batts should provide roughly 3 times the amp hours of a group 27. I chose that brand because it's available at Sam's club for a reasonable price, made by East Penn (deka), and has good reviews here and elsewhere. Yes, you're right, they need to be wired in series with each other and parallel with your other battery (via your battery switch). As Stu said, spend some time browsing the Compass Marine site.