Replacing Lifeline AGM Batteries

[Patches]

Love my 3 new Firefly AGMs!  With the guidance from Mainesail (and others here), and several key components purchased from him, I am running the new Engel combo fridge/freezer with (seeming) impunity.  Ice!

Everything fit well in the existing Mark 1 battery compartment.  Special shout out to Jon W. for his thorough "electrical upgrade" posts which helped me with design/components/layout.  I use the Firefly house bank for starting as well.  The 105 amp CMI alternator I bought from Rod also dropped in amazingly well, and I have been using the same belt since February with no signs of abnormal belt wear.

Battery monitor consistently shows > 95+% state of charge, without plugging in overnight.  But the boat goes out 3X/day for charters and the alternator keeps up with the relatively minor electrical demand.

Patches

[waughoo]

Patches,

Great feedback!  As time goes by, I'm starting to think the firefly set up would be the way to go for me until the LiFePo gets a bit more main stream.  A sort of bridge battery bank from lead acid to lithium.

[Ron Hill]

Guys : I changed to 3 105AH AGMs years ago. I wrote a Mainsheet Tech note article on how to fit those larger batteries into a MK 1 battery compartment.   

A thought

[Admiral_Swellson]

Firefly is more expensive, less energy dense, heavier weight, has much shorter cycles lifespan, can't charge as fast, but other than that I can't fault them.
I'm sure they somehow make sense for some owners but I couldn't rationalize it. I know the people who sell them, love them.

[Ron Hill]

Guys : FYI, Duracell make a 105 AH AGM battery.  I've seen them at Sams Club and Batteries Plus!!

A thought

[mainesail]

Guys : FYI, Duracell make a 105 AH AGM battery.  I've seen them at Sams Club and Batteries Plus!!

A thought

East Penn simply licenses the Duracell name. Those are nothing more than East Penn / Deka AGM's with a different sticker. They are the identical batteries as sold at Batteries Plus, NAPA, West Marine etc... They are not a good choice for a battery that will be deep cycled... We will only install those AGM's as starting batteries.

[Ron Hill]

Patches : I'm not too sure of your AH budget, but I cruised and annually overnighted just over 100 nights a year.  I only had a small inverter for the laptop printer, but ran the Fridge 24/7. I usually anchored 6 nights a week and 1 night at a marina (dump garbage, pump out and send US Mail)!!  [That's showing your age!!]

I got over about 7 years out of those 3 105 AH AGM batteries (replaced them once) and never cycled them below 70%?   I also had two small solar panels that would catch the late afternoon and early morning sun !!

A few thoughts

[wingman]

Guys, thanks for all the advice, update on battery project.

I considered the options discussed (golf cart batteries, lithium, etc.), but ultimately decided to keep the original setup with three lifeline AGM (2 4d house, one starter).

The PO put together a well-thought-out system with ACR, battery monitor, smart regulator, and inverter/charger and the original batteries lasted 8 years, so decided to stick with what has worked. Let's hope the new ones, installed last week, will last that long.

[waughoo]

Sounds like a sound decision. Changing battery chemestry often triggers a significant upgrade of all the ancillaries which can be valuable if you need it, but the project becomes signifocantly more involved.

[Stu Jackson]

1.  Sounds like a sound decision.

2.  Changing battery chemistry often triggers a significant upgrade of all the ancillaries which can be valuable if you need it, but the project becomes significantly more involved.

Alex,

1.  Perhaps for him.

Let's hope the new ones, installed last week, will last that long.

Remember Maine Sail's very prescient advice:  Batteries don't die, they are murdered. You have a very good system, and it won't take long to learn how to use it.  All the best.

2.  Not necessarily.  It truly depends on which "direction" you go.  Wet cells to AGM require larger alternators because the acceptance of AGMs is far higher than wet cells, although AGMs are not good at PSOC.  A change to lithium requires a complete re-investigation and analysis of a boat's electrical system - and I mean complete.  The myth of "drop in lithium" is just that.

[Ron Hill]

Guys : With many of the Tesla autos burning up, I would think hard about which Lithium batterys I installed!!!

A thought