What Starter Battery???

[Tally Ho]

I was running my boat on 2 Sams Duracell 6-volt golf cart batteries for the past 2 or 3 seasons. As the batteries wear and when I am away from the dock for a few days with no solar (and a fridge running), I decided to add a second battery. My boat was set up for a 2-bank system (1-2-Both-Off switch and the wiring. But I was only using the #1 battery (with the 2 GC batteries in series).

My decision, because it was the cheapest and Fastest was to add a deep cycle group 24 battery as the #2 battery. I do everything on the house bank, but when on shore power, I switch to Both on the battery switch and that charges it. The idea is that should I ever do something bad and drain the house bank, I can still switch to the backup battery and start the engine.

Greg

 

[Dalliance]

All extremily good advice above.
On a slight pessimistic opinion, I always go for the largest size battery (within reason) that will fit the space. fit my budget and that I will be able to charge.
With this in mind I will hopefully have the backup power I need if the occasion arises.

I subscribe to the same thinking and actually scaled down my battery size this year.
I’ve used two Group 27 deep cell batteries for years with no problems except I can’t get them in and out of the boat myself without suffering for weeks after and they barely fit in the compartment, so this year I switched to a pair of Group 24 deep cells. Still heavy, but a bit more manageable. The idea of four golf cart batteries is becoming more appealing, but I’m not sure about the space available.
The Group 24 cold cranking amps are the same as the Group 27. I don’t recall how the amp hours compared, probably a bit lower, but I alternate days using Battery 1 or Battery 2 and they’re both on the shore charger all the time at the dock. We’ll see how they work out.

 

[Jkutyna]

X2Power BCI Group 24M 12V 76AH 840CCA AGM Deep Cycle Marine & RV Battery - SLI24AGMDPM

Shop Batteries Plus for the X2Power 12V Group 24 AGM marine and RV deep cycle battery with 76 AH capacity. Offers both incredible starting power and deep capacity.

www.batteriesplus.com

X2 Group 24 is what I placed in my 33.5 last fall when I bought the boat. Previous owner was a bigtime walmart/home depot believer as my boat is littered in non stainless steel and other non marine rated equipment. It had some walmart special for the starter which of course was dead as a doornail. I personally would never put anything non-marine rated in the boat, especially as the starter/backup battery. They come with enough cranking amps to start the auxiliary as well as enough amp hours to provide backup 12v supply to critical loads (such as fans and lights while working in the boatyard.) Marine batteries also have fully sealed and tinned terminals, not bare copper which is a very bad idea in a saltwater environment.

I will probably get a second identical battery to this and tie them together as backup for each other. Of course the secondary battery bank will be fully LiFePo4 and the two separate banks would be connected together with a DC-DC charging system so the aux can charge the primary while the solar chargers can charge the backup.

I could probably be wrong in this but I'd rather spend the money than being cheap.

 

[dlochner]

X2Power BCI Group 24M 12V 76AH 840CCA AGM Deep Cycle Marine & RV Battery - SLI24AGMDPM

Shop Batteries Plus for the X2Power 12V Group 24 AGM marine and RV deep cycle battery with 76 AH capacity. Offers both incredible starting power and deep capacity.

www.batteriesplus.com

X2 Group 24 is what I placed in my 33.5 last fall when I bought the boat. Previous owner was a bigtime walmart/home depot believer as my boat is littered in non stainless steel and other non marine rated equipment. It had some walmart special for the starter which of course was dead as a doornail. I personally would never put anything non-marine rated in the boat, especially as the starter/backup battery. They come with enough cranking amps to start the auxiliary as well as enough amp hours to provide backup 12v supply to critical loads (such as fans and lights while working in the boatyard.) Marine batteries also have fully sealed and tinned terminals, not bare copper which is a very bad idea in a saltwater environment.

I will probably get a second identical battery to this and tie them together as backup for each other. Of course the secondary battery bank will be fully LiFePo4 and the two separate banks would be connected together with a DC-DC charging system so the aux can charge the primary while the solar chargers can charge the backup.

I could probably be wrong in this but I'd rather spend the money than being cheap.

If you haven't seen the article below, it is worth the read. Rod has many articles on boat electrical systems including batteries. Spend some time on his site as many of us have.

Easy LiFePo4 Conversion - Marine How To

Easy LiFePo4 Conversion Before reading this article please read the 101 article on Drop-In's: Drop-In Batteries Be An Educated Consumer Hardly a day goes by where we don't see or hear

marinehowto.com